AD9958BCPZ

2-Channel, 500 MSPS DDS with 10-Bit DACs AD9958 Data Sheet FEATURES APPLICATIONS 2 synchronized DDS channels @ 500 MSPS Independent frequency/phase/amplitude control between channels Matched latencies for frequency/phase/amplitude changes Excellent channel-to-channel isolation (>72 dB) Linear frequency/phase/amplitude sweeping capability Up to 16 levels of frequency/phase/amplitude modulation (pin-selectable) 2 integrated 10-bit digital-to-analog converters (DACs) Individually programmable DAC full-scale currents 0.12 Hz or better frequency tuning resolution 14-bit phase offset resolution 10-bit output amplitude scaling resolution Serial I/O port interface (SPI) with 800 Mbps data throughput Software-/hardware-controlled power-down Dual supply operation (1.8 V DDS core/3.3 V serial I/O) Multiple device synchronization Selectable 4× to 20× REFCLK multiplier (PLL) Selectable REFCLK crystal oscillator 56-lead LFCSP Agile local oscillators Phased array radars/sonars Instrumentation Synchronized clocking RF source for AOTF Single-side band suppressed carriers Quadrature communications FUNCTIONAL BLOCK DIAGRAM AD9958 (2) 500MSPS DDS CORES 10-BIT DAC RECONSTRUCTED SINE WAVE 10-BIT DAC RECONSTRUCTED SINE WAVE MODULATION CONTROL REF CLOCK INPUT CIRCUITRY TIMING AND CONTROL USER INTERFACE 05252-000 SYSTEM CLOCK SOURCE Figure 1. Rev. C Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 ©2005–2016 Analog Devices, Inc. All rights reserved. Technical Support www.analog.com AD9958 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Applications ....................................................................................... 1 Functional Block Diagram .............................................................. 1 Revision History ............................................................................... 2 General Description ......................................................................... 3 Specifications..................................................................................... 4 Absolute Maximum Ratings ............................................................ 8 ESD Caution .................................................................................. 8 Pin Configuration and Function Descriptions ............................. 9 Typical Performance Characteristics ........................................... 11 Application Circuits ....................................................................... 14 Equivalent Input and Output Circuits ......................................... 17 Theory of Operation ...................................................................... 18 DDS Core..................................................................................... 18 Digital-to-Analog Converter .................................................... 18 Modes of Operation ....................................................................... 19 Channel Constraint Guidelines ................................................ 19 Power Supplies ............................................................................ 19 Single-Tone Mode ...................................................................... 19 Reference Clock Modes ............................................................. 20 Scalable DAC Reference Current Control Mode ................... 21 Power-Down Functions ............................................................. 21 Modulation Mode....................................................................... 21 Modulation Using SDIO_x Pins for RU/RD .......................... 24 Linear Sweep Mode .................................................................... 25 Linear Sweep No-Dwell Mode ................................................. 26 Sweep and Phase Accumulator Clearing Functions .............. 27 Output Amplitude Control Mode ............................................ 28 Synchronizing Multiple AD9958 Devices ................................... 29 Automatic Mode Synchronization ........................................... 29 Manual Software Mode Synchronization ................................ 29 Manual Hardware Mode Synchronization .............................. 29 I/O_UPDATE, SYNC_CLK, and System Clock Relationships ............................................................................... 30 Serial I/O Port ................................................................................. 31 Overview ..................................................................................... 31 Instruction Byte Description .................................................... 32 Serial I/O Port Pin Description ................................................ 32 Serial I/O Port Function Description ...................................... 32 MSB/LSB Transfer Description ................................................ 32 Serial I/O Modes of Operation ................................................. 33 Register Maps and Bit Descriptions ............................................. 36 Register Maps .............................................................................. 36 Descriptions for Control Registers .......................................... 39 Descriptions for Channel Registers ......................................... 41 Outline Dimensions ....................................................................... 44 Ordering Guide .......................................................................... 44 REVISION HISTORY 11/2016—Rev. B to Rev. C Change to Figure 37 Caption ........................................................ 26 4/2013—Rev. A to Rev. B Changes to Linear Sweep Mode Section and Setting the Slope of the Linear Sweep ............................................................................. 25 Changes to Figure 38 and Figure 39 Captions ............................ 27 Changes to Ramp Rate Timer Section ......................................... 28 Updated Outline Dimensions ....................................................... 44 7/2008—Rev. 0 to Rev. A Changes to Features.......................................................................... 1 Inserted Figure 1; Renumbered Sequentially ................................ 1 Changes to Input Level Parameter in Table 1 ............................... 4 Added Profile Pin Toggle Rate Parameter in Table 1 ................... 6 Changes to Layout ............................................................................ 8 Changes to Table 3 ............................................................................ 9 Added Equivalent Input and Output Circuits Section .............. 17 Changes to Reference Clock Input Circuitry Section ................ 20 Change to Figure 35 ....................................................................... 21 Changes to Setting the Slope of the Linear Sweep Section ....... 25 Changes to Figure 37...................................................................... 26 Changes to Figure 38 and Figure 39 ............................................ 27 Changes to Figure 40...................................................................... 30 Added Table 25; Renumbered Sequentially ................................ 31 Changes to Figure 41...................................................................... 31 Changes to Figure 42, Serial Data I/O (SDIO_0, SDIO_1, SDIO_3) Section, and Added Example Instruction Byte Section .............................................................................................. 32 Added Table 27 ............................................................................... 33 Changes to Figure 46, Figure 47, Figure 48, and Figure 49 ...... 35 Changes to Register Maps and Bit Descriptions Section and Added Endnote 2 to Table 28........................................................ 36 Added Endnote 1 to Table 30........................................................ 38 Added Exposed Pad Notation to Outline Dimensions ............. 44 9/2005—Revision 0: Initial Version Rev. C | Page 2 of 44 Data Sheet AD9958 GENERAL DESCRIPTION The DAC outputs are supply referenced and must be terminated into AVDD by a resistor or an AVDD center-tapped transformer. Each DAC has its own programmable reference to enable different full-scale currents for each channel. The AD9958 consists of two DDS cores that provide independent frequency, phase, and amplitude control on each channel. This flexibility can be used to correct imbalances between signals due to analog processing, such as filtering, amplification, or PCB layout related mismatches. Because both channels share a common system clock, they are inherently synchronized. Synchronization of multiple devices is supported. The DDS acts as a high resolution frequency divider with the REFCLK as the input and the DAC providing the output. The REFCLK input source is common to both channels and can be driven directly or used in combination with an integrated REFCLK multiplier (PLL) up to a maximum of 500 MSPS. The PLL multiplication factor is programmable from 4 to 20, in integer steps. The REFCLK input also features an oscillator circuit to support an external crystal as the REFCLK source. The crystal must be between 20 MHz and 30 MHz. The crystal can be used in combination with the REFCLK multiplier. The AD9958 can perform up to a 16-level modulation of frequency, phase, or amplitude (FSK, PSK, ASK). Modulation is performed by applying data to the profile pins. In addition, the AD9958 also supports linear sweep of frequency, phase, or amplitude for applications such as radar and instrumentation. The AD9958 serial I/O port offers multiple configurations to provide significant flexibility. The serial I/O port offers an SPIcompatible mode of operation that is virtually identical to the SPI operation found in earlier Analog Devices, Inc., DDS products. Flexibility is provided by four data pins (SDIO_0/ SDIO_1/SDIO_2/SDIO_3) that allow four programmable modes of serial I/O operation. The AD9958 comes in a space-saving 56-lead LFCSP package. The DDS core (AVDD and DVDD pins) is powered by a 1.8 V supply. The digital I/O interface (SPI) operates at 3.3 V and requires the pin labeled DVDD_I/O (Pin 49) be connected to 3.3 V. The AD9958 operates over the industrial temperature range of −40°C to +85°C. The AD9958 uses advanced DDS technology that provides low power dissipation with high performance. The device incorporates two integrated, high speed 10-bit DACs with excellent wideband and narrow-band SFDR. Each channel has a dedicated 32-bit frequency tuning word, 14 bits of phase offset, and a 10-bit output scale multiplier. AD9958 DDS CORE Σ 32 32 Σ Σ 15 COS(X) 10 10 DAC 10 10 DAC CH0_IOUT CH0_IOUT DDS CORE 32 FTW ∆FTW 32 32 SYNC_IN SYNC_OUT I/O_UPDATE SYNC_CLK Σ PHASE/ ∆PHASE 15 COS(X) 14 AMP/ ∆AMP SCALABLE DAC REF CURRENT 10 TIMING AND CONTROL LOGIC SYSTEM CLK ÷4 REF_CLK REF_CLK Σ BUFFER/ XTAL OSCILLATOR CLK_MODE_SEL REF CLOCK MULTIPLIER 4× TO 20× CH1_IOUT CH1_IOUT DAC_RSET PWR_DWN_CTL MASTER_RESET CONTROL REGISTERS MUX I/O PORT BUFFER CHANNEL REGISTERS PROFILE REGISTERS 1.8V 1.8V AVDD DVDD Figure 2. Detailed Block Diagram Rev. C | Page 3 of 44 P0 P1 P2 P3 DVDD_I/O SCLK CS SDIO_0 SDIO_1 SDIO_2 SDIO_3 05252-001 Σ AD9958 Data Sheet SPECIFICATIONS AVDD and DVDD = 1.8 V ± 5%; DVDD_I/O = 3.3 V ± 5%; T = 25°C; RSET = 1.91 kΩ; external reference clock frequency = 500 MSPS (REFCLK multiplier bypassed), unless otherwise noted. Table 1. Parameter REFERENCE CLOCK INPUT CHARACTERISTICS Frequency Range REFCLK Multiplier Bypassed REFCLK Multiplier Enabled Internal VCO Output Frequency Range VCO Gain Control Bit Set High 1 VCO Gain Control Bit Set Low1 Crystal REFCLK Source Range Input Level Input Voltage Bias Level Input Capacitance Input Impedance Duty Cycle with REFCLK Multiplier Bypassed Duty Cycle with REFCLK Multiplier Enabled CLK Mode Select (Pin 24) Logic 1 Voltage CLK Mode Select (Pin 24) Logic 0 Voltage DAC OUTPUT CHARACTERISTICS Resolution Full-Scale Output Current Gain Error Channel-to-Channel Output Amplitude Matching Error Output Current Offset Differential Nonlinearity Integral Nonlinearity Output Capacitance Voltage Compliance Range Channel-to-Channel Isolation WIDEBAND SFDR 1 MHz to 20 MHz Analog Output 20 MHz to 60 MHz Analog Output 60 MHz to 100 MHz Analog Output 100 MHz to 150 MHz Analog Output 150 MHz to 200 MHz Analog Output NARROW-BAND SFDR 1.1 MHz Analog Output (±10 kHz) 1.1 MHz Analog Output (±50 kHz) 1.1 MHz Analog Output (±250 kHz) 1.1 MHz Analog Output (±1 MHz) 15.1 MHz Analog Output (±10 kHz) 15.1 MHz Analog Output (±50 kHz) 15.1 MHz Analog Output (±250 kHz) 15.1 MHz Analog Output (±1 MHz) 40.1 MHz Analog Output (±10 kHz) 40.1 MHz Analog Output (±50 kHz) 40.1 MHz Analog Output (±250 kHz) 40.1 MHz Analog Output (±1 MHz) 75.1 MHz Analog Output (±10 kHz) Min Typ Max Unit 1 10 500 125 MHz MHz 255 100 20 200 500 160 30 1000 MHz MHz MHz mV V pF Ω % % V V 1.15 2 1500 45 35 1.25 55 65 1.8 0.5 1.25 −10 −2.5 1 ±0.5 ±1.0 3 AVDD − 0.50 72 10 10 +10 +2.5 25 AVDD + 0.50 Measured at each pin (single-ended) 1.8 V digital input logic 1.8 V digital input logic Must be referenced to AVDD Bits mA % FS % µA LSB LSB pF V dB −65 −62 −59 −56 −53 dBc dBc dBc dBc dBc −90 −88 −86 −85 −90 −87 −85 −83 −90 −87 −84 −82 −87 dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc Rev. C | Page 4 of 44 Test Conditions/Comments See Figure 34 and Figure 35 DAC supplies tied together (see Figure 19) The frequency range for wideband SFDR is defined as dc to Nyquist Data Sheet Parameter 75.1 MHz Analog Output (±50 kHz) 75.1 MHz Analog Output (±250 kHz) 75.1 MHz Analog Output (±1 MHz) 100.3 MHz Analog Output (±10 kHz) 100.3 MHz Analog Output (±50 kHz) 100.3 MHz Analog Output (±250 kHz) 100.3 MHz Analog Output (±1 MHz) 200.3 MHz Analog Output (±10 kHz) 200.3 MHz Analog Output (±50 kHz) 200.3 MHz Analog Output (±250 kHz) 200.3 MHz Analog Output (±1 MHz) PHASE NOISE CHARACTERISTICS Residual Phase Noise @ 15.1 MHz (fOUT) @ 1 kHz Offset @ 10 kHz Offset @ 100 kHz Offset @ 1 MHz Offset Residual Phase Noise @ 40.1 MHz (fOUT) @ 1 kHz Offset @ 10 kHz Offset @ 100 kHz Offset @ 1 MHz Offset Residual Phase Noise @ 75.1 MHz (fOUT) @ 1 kHz Offset @ 10 kHz Offset @ 100 kHz Offset @ 1 MHz Offset Residual Phase Noise @ 100.3 MHz (fOUT) @ 1 kHz Offset @ 10 kHz Offset @ 100 kHz Offset @ 1 MHz Offset Residual Phase Noise @ 15.1 MHz (fOUT) with REFCLK Multiplier Enabled 5× @ 1 kHz Offset @ 10 kHz Offset @ 100 kHz Offset @ 1 MHz Offset Residual Phase Noise @ 40.1 MHz (fOUT) with REFCLK Multiplier Enabled 5× @ 1 kHz Offset @ 10 kHz Offset @ 100 kHz Offset @ 1 MHz Offset Residual Phase Noise @ 75.1 MHz (fOUT) with REFCLK Multiplier Enabled 5× @ 1 kHz Offset @ 10 kHz Offset @ 100 kHz Offset @ 1 MHz Offset Residual Phase Noise @ 100.3 MHz (fOUT) with REFCLK Multiplier Enabled 5× @ 1 kHz Offset @ 10 kHz Offset @ 100 kHz Offset @ 1 MHz Offset AD9958 Min Typ −85 −83 −82 −87 −85 −83 −81 −87 −85 −83 −81 Max Unit dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc −150 −159 −165 −165 dBc/Hz dBc/Hz dBc/Hz dBc/Hz −142 −151 −160 −162 dBc/Hz dBc/Hz dBc/Hz dBc/Hz −135 −146 −154 −157 dBc/Hz dBc/Hz dBc/Hz dBc/Hz −134 −144 −152 −154 dBc/Hz dBc/Hz dBc/Hz dBc/Hz −139 −149 −153 −148 dBc/Hz dBc/Hz dBc/Hz dBc/Hz −130 −140 −145 −139 dBc/Hz dBc/Hz dBc/Hz dBc/Hz −123 −134 −138 −132 dBc/Hz dBc/Hz dBc/Hz dBc/Hz −120 −130 −135 −129 dBc/Hz dBc/Hz dBc/Hz dBc/Hz Rev. C | Page 5 of 44 Test Conditions/Comments AD9958 Parameter Residual Phase Noise @ 15.1 MHz (fOUT) with REFCLK Multiplier Enabled 20× @ 1 kHz Offset @ 10 kHz Offset @ 100 kHz Offset @ 1 MHz Offset Residual Phase Noise @ 40.1 MHz (fOUT) with REFCLK Multiplier Enabled 20× @ 1 kHz Offset @ 10 kHz Offset @ 100 kHz Offset @ 1 MHz Offset Residual Phase Noise @ 75.1 MHz (fOUT) with REFCLK Multiplier Enabled 20× @ 1 kHz Offset @ 10 kHz Offset @ 100 kHz Offset @ 1 MHz Offset Residual Phase Noise @ 100.3 MHz (fOUT) with REFCLK Multiplier Enabled 20× @ 1 kHz Offset @ 10 kHz Offset @ 100 kHz Offset @ 1 MHz Offset SERIAL PORT TIMING CHARACTERISTICS Maximum Frequency Serial Clock (SCLK) Minimum SCLK Pulse Width Low (tPWL) Minimum SCLK Pulse Width High (tPWH) Minimum Data Setup Time (tDS) Minimum Data Hold Time Minimum CS Setup Time (tPRE) Minimum Data Valid Time for Read Operation MISCELLANEOUS TIMING CHARACTERISTICS MASTER_RESET Minimum Pulse Width I/O_UPDATE Minimum Pulse Width Minimum Setup Time (I/O_UPDATE to SYNC_CLK) Minimum Hold Time (I/O_UPDATE to SYNC_CLK) Minimum Setup Time (Profile Inputs to SYNC_CLK) Minimum Hold Time (Profile Inputs to SYNC_CLK) Minimum Setup Time (SDIO Inputs to SYNC_CLK) Minimum Hold Time (SDIO Inputs to SYNC_CLK) Propagation Time Between REF_CLK and SYNC_CLK Profile Pin Toggle Rate CMOS LOGIC INPUTS VIH VIL Logic 1 Current Logic 0 Current Input Capacitance CMOS LOGIC OUTPUTS VOH VOL Data Sheet Min Typ Max −127 −136 −139 −138 dBc/Hz dBc/Hz dBc/Hz dBc/Hz −117 −128 −132 −130 dBc/Hz dBc/Hz dBc/Hz dBc/Hz −110 −121 −125 −123 dBc/Hz dBc/Hz dBc/Hz dBc/Hz −107 −119 −121 −119 dBc/Hz dBc/Hz dBc/Hz dBc/Hz 200 1.6 2.2 2.2 0 1.0 12 1 1 4.8 0 5.4 0 2.5 0 2.25 Unit 3.5 5.5 2 2.0 3 −12 2 0.8 12 Test Conditions/Comments MHz ns ns ns ns ns ns ns ns ns ns ns ns ns Sync clocks Min pulse width = 1 sync clock period Min pulse width = 1 sync clock period Rising edge to rising edge Rising edge to rising edge V V µA µA pF 1 mA load 2.7 0.4 Rev. C | Page 6 of 44 V V Data Sheet Parameter POWER SUPPLY Total Power Dissipation—Both Channels On, SingleTone Mode Total Power Dissipation—Both Channels On, with Sweep Accumulator Total Power Dissipation—Full Power-Down IAVDD—Both Channels On, Single-Tone Mode IAVDD—Both Channels On, Sweep Accumulator, REFCLK Multiplier, and 10-Bit Output Scalar Enabled IDVDD—Both Channels On, Single-Tone Mode IDVDD—Both Channels On, Sweep Accumulator, REFCLK Multiplier, and 10-Bit Output Scalar Enabled IDVDD_I/O IAVDD Power-Down Mode IDVDD Power-Down Mode DATA LATENCY (PIPELINE DELAY) SINGLE-TONE MODE 2, 3 Frequency, Phase, and Amplitude Words to DAC Output with Matched Latency Enabled Frequency Word to DAC Output with Matched Latency Disabled Phase Offset Word to DAC Output with Matched Latency Disabled Amplitude Word to DAC Output with Matched Latency Disabled DATA LATENCY (PIPELINE DELAY) MODULATION MODE3, 4 Frequency Word to DAC Output Phase Offset Word to DAC Output Amplitude Word to DAC Output DATA LATENCY (PIPELINE DELAY) LINEAR SWEEP MODE3, 4 Frequency Rising/Falling Delta-Tuning Word to DAC Output Phase Offset Rising/Falling Delta-Tuning Word to DAC Output Amplitude Rising/Falling Delta-Tuning Word to DAC Output AD9958 Min Typ Max Unit Test Conditions/Comments 315 380 mW Dominated by supply variation 350 420 mW Dominated by supply variation 13 90 95 105 110 mW mA mA 60 70 70 80 mA mA 22 30 2.5 2.5 mA mA mA mA 29 SYSCLKs 29 SYSCLKs 25 SYSCLKs 17 SYSCLKs 34 29 21 SYSCLKs SYSCLKs SYSCLKs 41 SYSCLKs 37 SYSCLKs 29 SYSCLKs For the VCO frequency range of 160 MHz to 255 MHz, there is no guarantee of operation. Data latency is referenced to I/O_UPDATE. Data latency is fixed. 4 Data latency is referenced to a profile change. 1 2 3 Rev. C | Page 7 of 44 IDVDD = read IDVDD = write AD9958 Data Sheet ABSOLUTE MAXIMUM RATINGS Table 2. Parameter Maximum Junction Temperature DVDD_I/O (Pin 49) AVDD, DVDD Digital Input Voltage (DVDD_I/O = 3.3 V) Digital Output Current Storage Temperature Range Operating Temperature Range Lead Temperature (10 sec Soldering) θJA θJC Rating 150°C 4V 2V −0.7 V to +4 V 5 mA –65°C to +150°C –40°C to +85°C 300°C 21°C/W 2°C/W Stresses at or above those listed under Absolute Maximum Ratings may cause permanent damage to the product. This is a stress rating only; functional operation of the product at these or any other conditions above those indicated in the operational section of this specification is not implied. Operation beyond the maximum operating conditions for extended periods may affect product reliability. ESD CAUTION Rev. C | Page 8 of 44 Data Sheet AD9958 56 55 54 53 52 51 50 49 48 47 46 45 44 43 DGND DVDD SYNC_CLK SDIO_3 SDIO_2 SDIO_1 SDIO_0 DVDD_I/O SCLK CS I/O_UPDATE DVDD DGND P3 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 PIN 1 INDICATOR AD9958 TOP VIEW (Not to Scale) 42 41 40 39 38 37 36 35 34 33 32 31 30 29 P2 P1 P0 AVDD NC AVDD AVDD AVDD NC AVDD NC AVDD AVDD AVDD NOTES 1. THE EXPOSED EPAD ON BOTTOM SIDE OF PACKAGE IS AN ELECTRICAL CONNECTION AND MUST BE SOLDERED TO GROUND. 2. PIN 49 IS DVDD_I/O AND IS TIED TO 3.3V. 3. NC = NO CONNECT. 05252-005 AVDD AGND DAC_RSET AGND AVDD AGND AVDD REF_CLK REF_CLK CLK_MODE_SEL AGND AVDD LOOP_FILTER NC 15 16 17 18 19 20 21 22 23 24 25 26 27 28 SYNC_IN SYNC_OUT MASTER_RESET PWR_DWN_CTL AVDD AGND AVDD CH0_IOUT CH0_IOUT AGND AVDD AGND CH1_IOUT CH1_IOUT Figure 3. Pin Configuration Table 3. Pin Function Descriptions Pin No. 1 Mnemonic SYNC_IN I/O 1 I 2 SYNC_OUT O 3 MASTER_RESET I 4 5, 7, 11, 15, 19, 21, 26, 29, 30, 31, 33, 35, 36, 37, 39 6, 10, 12, 16, 18, 20, 25 45, 55 44, 56 8 9 13 14 17 PWR_DWN_CTL AVDD I I Description Used to Synchronize Multiple AD9958 Devices. Connects to the SYNC_OUT pin of the master AD9958 device. Used to Synchronize Multiple AD9958 Devices. Connects to the SYNC_IN pin of the slave AD9958 devices. Active High Reset Pin. Asserting the MASTER_RESET pin forces the AD9958 internal registers to their default state, as described in the Register Maps and Bit Descriptions section. External Power-Down Control. Analog Power Supply Pins (1.8 V). AGND I Analog Ground Pins. DVDD DGND CH0_IOUT CH0_IOUT CH1_IOUT CH1_IOUT DAC_RSET I I O O O O I 22 REF_CLK I 23 REF_CLK I Digital Power Supply Pins (1.8 V). Digital Power Ground Pins. True DAC Output. Terminates into AVDD. Complementary DAC Output. Terminates into AVDD. True DAC Output. Terminates into AVDD. Complementary DAC Output. Terminates into AVDD. Establishes the Reference Current for All DACs. A 1.91 kΩ resistor (nominal) is connected from Pin 17 to AGND. Complementary Reference Clock/Oscillator Input. When the REF_CLK is operated in single-ended mode, this pin should be decoupled to AVDD or AGND with a 0.1 µF capacitor. Reference Clock/Oscillator Input. When the REF_CLK is operated in single-ended mode, this is the input. See the Modes of Operation section for the reference clock configuration. Rev. C | Page 9 of 44 AD9958 Data Sheet Pin No. 24 Mnemonic CLK_MODE_SEL I/O 1 I 27 LOOP_FILTER I 28, 32, 34, 38 40, 41, 42, 43 NC P0, P1, P2, P3 N/A I 46 I/O_UPDATE I 47 48 CS SCLK I I 49 50 51, 52, 53 DVDD_I/O SDIO_0 SDIO_1, SDIO_2, SDIO_3 I I/O I/O 54 SYNC_CLK O 1 Description Control Pin for the Oscillator Section. Caution: Do not drive this pin beyond 1.8 V. When high (1.8 V), the oscillator section is enabled to accept a crystal as the REF_CLK source. When low, the oscillator section is bypassed. Connects to the external zero compensation network of the PLL loop filter. Typically, the network consists of a 0 Ω resistor in series with a 680 pF capacitor tied to AVDD. No Connection. Data pins used for modulation (FSK, PSK, ASK), to start/stop for the sweep accumulators, or used to ramp up/ramp down the output amplitude. The data is synchronous to the SYNC_CLK (Pin 54). The data inputs must meet the setup and hold time requirements to the SYNC_CLK. The functionality of these pins is controlled by profile pin configuration (PPC) bits (FR1[14:12]). A rising edge transfers data from the serial I/O port buffer to active registers. I/O_UPDATE is synchronous to the SYNC_CLK (Pin 54). I/O_UPDATE must meet the setup and hold time requirements to the SYNC_CLK to guarantee a fixed pipeline delay of data to the DAC output; otherwise, a ±1 SYNC_CLK period of pipeline uncertainty exists. The minimum pulse width is one SYNC_CLK period. Active Low Chip Select. Allows multiple devices to share a common I/O bus (SPI). Serial Data Clock for I/O Operations. Data bits are written on the rising edge of SCLK and read on the falling edge of SCLK. 3.3 V Digital Power Supply for SPI Port and Digital I/O. Data Pin SDIO_0 is dedicated to the serial port I/O only. Data Pin SDIO_1, Data Pin SDIO_2, and Data Pin SDIO_3 can be used for the serial I/O port or used to initiate a ramp-up/ramp-down (RU/RD) of the DAC output amplitude. The SYNC_CLK runs at one fourth the system clock rate. It can be disabled. I/O_UPDATE or data (Pin 40 to Pin 43) is synchronous to the SYNC_CLK. To guarantee a fixed pipeline delay of data to DAC output, I/O_UPDATE or data (Pin 40 to Pin 43) must meet the setup and hold time requirements to the rising edge of SYNC_CLK; otherwise, a ±1 SYNC_CLK period of uncertainty exists. I = input, O = output. Rev. C | Page 10 of 44 Data Sheet AD9958 TYPICAL PERFORMANCE CHARACTERISTICS DELTA 1 (T1) –71.73dB 4.50901804MHz REF LVL 0dBm RBW VBW SWT 20kHz 20kHz 1.6s RF ATT 20dB UNIT dB REF LVL 0dBm 0 0 A –30 –40 –40 –50 RF ATT 20dB UNIT dB A 1 1AP –50 –60 –60 –70 –70 –80 –80 05252-006 START 0Hz 25MHz/DIV STOP 250MHz –100 START 0Hz DELTA 1 (T1) –62.84dB 40.08016032MHz RBW VBW SWT 20kHz 20kHz 1.6s RF ATT 20dB UNIT dB STOP 250MHz 25MHz/DIV Figure 7. Wideband SFDR, fOUT = 15.1 MHz, fCLK = 500 MSPS Figure 4. Wideband SFDR, fOUT = 1.1 MHz, fCLK = 500 MSPS REF LVL 0dBm 05252-009 –90 –90 –100 REF Lv] 0dBm 0 A 1 –10 DELTA 1 (T1) –60.13dB 75.15030060MHz RBW VBW SWT 20kHz 20kHz 1.6s RF ATT 20dB UNIT dB A 1 –10 –20 –20 1AP –30 –30 –40 –40 (dB) –50 –60 1AP –50 –60 –70 –70 –80 –80 –90 25MHz/DIV STOP 250Hz –100 START 0Hz Figure 5. Wideband SFDR, fOUT = 40.1 MHz, fCLK = 500 MSPS REF LVL 0dBm DELTA 1 (T1) –59.04dB 100.70140281MHz RBW VBW SWT 20kHz 20kHz 1.6s RF ATT 20dB UNIT dB 25MHz/DIV STOP 250MHz Figure 8. Wideband SFDR, fOUT = 75.1 MHz, fCLK = 500 MSPS REF LVL 0dBm 0 RBW DELTA 1 (T1) VBW –53.84dB –101.20240481MHz SWT 20kHz 20kHz 1.6s RF ATT 20dB UNIT dB 0 A 1 –10 A 1 –10 –20 05252-010 START 0Hz –90 05252-007 –100 –20 1AP –30 –40 –40 (dB) –30 –50 –50 –60 –60 –70 –70 –80 –80 –90 1AP START 0Hz 25MHz/DIV STOP 250MHz 05252-008 –90 –100 Figure 6. Wideband SFDR, fOUT = 100.3 MHz, fCLK = 500 MSPS –100 START 0Hz 25MHz/DIV STOP 250MHz Figure 9. Wideband SFDR, fOUT = 200.3 MHz, fCLK = 500 MSPS Rev. C | Page 11 of 44 05252-011 (dB) 20kHz 20kHz 1.6s –20 1AP –30 (dB) (dB) –20 (dB) RBW VBW SWT –10 –10 0 DELTA 1 (T1) –69.47dB 30.06012024MHz AD9958 REF LVL 0dBm Data Sheet DELTA 1 (T1) –84.73dB 254.50901604kHz 0 RBW VBW SWT 500Hz 500Hz 20s RF ATT 20dB UNIT dB REF LVL 0dBm 1 dB A –20 1AP –30 –40 –40 (dB) –50 –50 –60 –60 –70 –70 –80 –80 –90 1AP CENTER 1.1MHz SPAN 1MHz 100kHz/DIV CENTER 15.1MHz Figure 10. NBSFDR, fOUT = 1.1 MHz, fCLK = 500 MSPS, ±1 MHz REF LVL 0dBm RBW VBW SWT DELTA 1 (T1) –84.10dB 120.24048096kHz 0 500Hz 500Hz 20s RF ATT 20dB UNIT dB 100kHz/DIV SPAN 1MHz Figure 13. NBSFDR, fOUT = 15.1 MHz, fCLK = 500 MSPS, ±1 MHz REF LVL 0dBm RBW VBW SWT DELTA 1 (T1) –86.03dB 262.56513026kHz 500Hz 500Hz 20s RF ATT 20dB UNIT dB 0 A 1 05252-015 05252-012 –90 –100 A 1 –10 –20 –20 1AP –30 –40 –40 (dB) –30 –50 –50 –60 –70 –70 –80 –80 –90 –90 05252-013 –60 –100 CENTER 40.1MHz 100kHz/DIV SPAN 1MHz –100 CENTER 75.1MHz Figure 11. NBSFDR, fOUT = 40.1 MHz, fCLK = 500 MSPS, ±1 MHz REF LVL 0dBm DELTA 1 (T1) –82.63dB 400.80160321kHz RBW VBW SWT 500Hz 500Hz 20s RF ATT 20dB UNIT dB 100kHz/DIV SPAN 1MHz Figure 14. NBSFDR, fOUT = 75.1 MHz, fCLK = 500 MSPS, ±1 MHz REF LVL 0dBm RBW VBW SWT DELTA 1 (T1) –83.72dB –400.80160321kHz 500Hz 500Hz 20s RF ATT 20dB UNIT dB 0 A 1 1AP 05252-016 –10 A 1 –10 –10 –20 –20 1AP –30 –40 –40 (dB) –30 –50 –50 –60 –70 –70 –80 –80 –90 –90 CENTER 100.3MHz 100kHz/DIV SPAN 1MHz 05252-014 –60 –100 1AP –100 CENTER 200.3MHz 100kHz/DIV SPAN 1MHz Figure 15. NBSFDR fOUT = 200. 3MHz, fCLK = 500 MSPS, , ±1 MHz Figure 12. NBSFDR, fOUT = 100.3 MHz, fCLK = 500 MSPS, ±1 MHz Rev. C | Page 12 of 44 05252-017 (dB) 20dB UNIT 1 –30 –100 (dB) RF ATT –10 –20 (dB) 500Hz 500Hz 20s 0 A –10 0 RBW VBW SWT DELTA 1 (T1) –84.86dB –200.40080160kHz Data Sheet AD9958 –100 –60 75.1MHz CHANNEL ISOLATION (dBc) PHASE NOISE (dBc/Hz) –110 –120 –130 100.3MHz –140 –150 40.1MHz –65 –70 SINGLE DAC POWER PLANE –75 –80 –160 15.1MHz –85 100 1k 10k 100k 1M 10M 05252-018 10 FREQUENCY OFFSET (Hz) Figure 16. Residual Phase Noise (SSB) with fOUT = 15.1 MHz, 40.1MHz, 75.1 MHz, 100.3 MHz; fCLK = 500 MHz with REFCLK Multiplier Bypassed 25.3 50.3 75.3 100.3 125.3 150.3 175.3 200.3 FREQUENCY OF COUPLING SPUR (MHz) 05252-021 SEPARATED DAC POWER PLANES –170 Figure 19. Channel Isolation at 500 MSPS Operation; Conditions are Channel of Interest Fixed at 110.3 MHz, the Other Channels Are Frequency Swept 600 –70 TOTAL POWER DISSIPATION (mW) –80 PHASE NOISE (dBc/Hz) –90 –100 100.3MHz –110 75.1MHz –120 –130 –140 40.1MHz –150 15.1MHz 500 400 2 CHANNELS ON 300 1 CHANNEL ON 200 100 100 1k 10k 100k 1M 10M FREQUENCY OFFSET (Hz) 0 05252-019 –170 10 Figure 17. Residual Phase Noise (SSB) with fOUT = 15.1 MHz, 40.1MHz, 75.1 MHz, 100.3 MHz; fCLK = 500 MHz with REFCLK Multiplier = 5× 500 450 400 350 300 250 200 150 100 REFERENCE CLOCK FREQUENCY (MHz) 50 05252-022 –160 Figure 20. Power Dissipation vs. Reference Clock Frequency vs. Channel(s) Power On/Off –45 –70 –80 –50 –100 SFDR AVERAGED 100.3MHz –110 –55 SFDR (dBc) PHASE NOISE (dBc/Hz) –90 75.1MHz –120 –130 40.1MHz –140 –60 –65 15.1MHz –150 –70 100 1k 10k 100k FREQUENCY OFFSET (Hz) 1M 10M Figure 18. Residual Phase Noise (SSB) with fOUT = 15.1 MHz, 40.1MHz, 75.1 MHz,100.3 MHz; fCLK = 500 MHz with REFCLK Multiplier = 20× Rev. C | Page 13 of 44 –75 1.1 15.1 40.1 75.1 100.3 fOUT (MHz) Figure 21. Averaged Channel SFDR vs. fOUT 200.3 05252-023 –170 10 05252-020 –160 AD9958 Data Sheet APPLICATION CIRCUITS PULSE ANTENNA RADIATING ELEMENTS AD9958 CH0 FILTER FILTER CH1 FILTER FILTER 05252-024 LO REFCLK Figure 22. Phase Array Radar Using Precision Frequency/Phase Control from DDS in FMCW or Pulsed Radar Applications; DDS Provides Either Continuous Wave or Frequency Sweep AD8348 AD8347 AD8346 ADL5390 I BASEBAND AD8349 CH0 LO AD9958 PHASE SPLITTER RF OUTPUT CH1 05252-025 REFCLK Q BASEBAND Figure 23. Single-Sideband-Suppressed Carrier Upconversion AD9510, AD9511, ADF4106 ÷ REFERENCE PHASE COMPARATOR CHARGE PUMP LOOP FILTER VCO ÷ LPF REFCLK 05252-026 AD9958 Figure 24. DDS in PLL Locking to Reference Offering Distribution with Fine Frequency and Delay Adjust Tuning Rev. C | Page 14 of 44 Data Sheet AD9958 AD9510 CLOCK DISTRIBUTOR WITH DELAY EQUALIZATION REF_CLK AD9510 SYNCHRONIZATION DELAY EQUALIZATION DATA FPGA SYNC_OUT C1 S1 SYNC_IN AD9958 SYNC_CLK C2 S2 DATA AD9958 FPGA C3 S3 DATA FPGA AD9958 A3 (SLAVE 2) SYNC_CLK FPGA A2 (SLAVE 1) SYNC_CLK CENTRAL CONTROL A1 (MASTER) C4 S4 DATA AD9958 A4 (SLAVE 3) SYNC_CLK A_END 05252-027 CLOCK SOURCE Figure 25. Synchronizing Multiple Devices to Increase Channel Capacity Using the AD9510 as a Clock Distributor for the Reference and SYNC_CLK OPTICAL FIBER CHANNEL WITH MULTIPLE DISCRETE WAVELENGTHS SPLITTER WDM SOURCE WDM SIGNAL INPUTS CH0 AD9958 REFCLK AMP CH0 ACOUSTIC OPTICAL TUNABLE FILTER CH1 AMP CH1 05252-028 OUTPUTS CH0 CH1 SELECTABLE WAVELENGTH FROM EACH CHANNEL VIA DDS TUNING AOTF Figure 26. DDS Providing Stimulus for Acoustic Optical Tunable Filter CH0 AD9958 CH1 + 05252-029 REFCLK – ADCMP563 Figure 27. Agile Clock Source with Duty Cycle Control Using the Phase Offset Value in DDS to Change the DC Voltage to the Comparator Rev. C | Page 15 of 44 AD9958 Data Sheet PROGRAMMABLE 1 TO 32 DIVIDER AND DELAY ADJUST CLOCK OUTPUT SELECTION(S) AD9515 AD9514 AD9513 AD9512 CH0 n LVPECL LVDS CMOS n LVPECL LVDS CMOS CH1 IMAGE AD9515 AD9514 AD9513 AD9512 n = DEPENDENT ON PRODUCT SELECTION 05252-030 AD9958 REFCLK Figure 28. Clock Generation Circuit Using the AD9512/AD9513/AD9514/AD9515 Series of Clock Distribution Chips Rev. C | Page 16 of 44 Data Sheet AD9958 EQUIVALENT INPUT AND OUTPUT CIRCUITS DVDD_I/O = 3.3V INPUT OUTPUT 05252-102 AVOID OVERDRIVING DIGITAL INPUTS. FORWARD BIASING DIODES MAY COUPLE DIGITAL NOISE ON POWER PINS. Figure 29. CMOS Digital Inputs TERMINATE OUTPUTS INTO AVDD. DO NOT EXCEED VOLTAGE COMPLIANCE OF OUTPUTS. 05252-132 CHx_IOUT CHx_IOUT Figure 30. DAC Outputs AVDD 1.5kΩ Z Z 1.5kΩ REF_CLK AVDD AVDD OSC AMP REF_CLK INPUTS ARE INTERNALLY BIASED AND NEED TO BE AC-COUPLED. OSC INPUTS ARE DC-COUPLED. Figure 31. REF_CLK/REF_CLK Inputs Rev. C | Page 17 of 44 OSC 05252-133 REF_CLK AD9958 Data Sheet THEORY OF OPERATION DDS CORE DIGITAL-TO-ANALOG CONVERTER The AD9958 has two DDS cores, each consisting of a 32-bit phase accumulator and phase-to-amplitude converter. Together, these digital blocks generate a digital sine wave when the phase accumulator is clocked and the phase increment value (frequency tuning word) is greater than 0. The phase-to-amplitude converter simultaneously translates phase information to amplitude information by a cos(θ) operation. The AD9958 incorporates four 10-bit current output DACs. The DAC converts a digital code (amplitude) into a discrete analog quantity. The DAC current outputs can be modeled as a current source with high output impedance (typically 100 kΩ). Unlike many DACs, these current outputs require termination into AVDD via a resistor or a center-tapped transformer for expected current flow. The output frequency (fOUT) of each DDS channel is a function of the rollover rate of each phase accumulator. The exact relationship is given in the following equation: Each DAC has complementary outputs that provide a combined full-scale output current (IOUT + IOUT). The outputs always sink (FTW )( f S ) 232 where: fS is the system clock rate. FTW is the frequency tuning word and is 0 ≤ FTW ≤ 231. 232 represents the phase accumulator capacity. Because both channels share a common system clock, they are inherently synchronized. The DDS core architecture also supports the capability to phase offset the output signal, which is performed by the channel phase offset word (CPOW). The CPOW is a 14-bit register that stores a phase offset value. This value is added to the output of the phase accumulator to offset the current phase of the output signal. Each channel has its own phase offset word register. This feature can be used for placing all channels in a known phase relationship relative to one another. The exact value of phase offset is given by the following equation: R SET = 18.91 I OUT (max) The maximum full-scale output current of the combined DAC outputs is 15 mA, but limiting the output to 10 mA provides optimal spurious-free dynamic range (SFDR) performance. The DAC output voltage compliance range is AVDD + 0.5 V to AVDD − 0.5 V. Voltages developed beyond this range may cause excessive harmonic distortion. Proper attention should be paid to the load termination to keep the output voltage within its compliance range. Exceeding this range could potentially damage the DAC output circuitry. POW Φ =  14  × 360°  2  LPF CHx_IOUT DAC AVDD CHx_IOUT 1:1 50Ω 05252-116 fOUT = current, and their sum equals the full-scale current at any point in time. The full-scale current is controlled by means of an external resistor (RSET) and the scalable DAC current control bits discussed in the Modes of Operation section. The resistor, RSET, is connected between the DAC_RSET pin and analog ground (AGND). The full-scale current is inversely proportional to the resistor value as follows: Figure 32. Typical DAC Output Termination Configuration Rev. C | Page 18 of 44 Data Sheet AD9958 MODES OF OPERATION There are many combinations of modes (for example, singletone, modulation, linear sweep) that the AD9958 can perform simultaneously. However, some modes require multiple data pins, which can impose limitations. The following guidelines can help determine if a specific combination of modes can be performed simultaneously by the AD9958. CHANNEL CONSTRAINT GUIDELINES • • • • • • • • • • • Single-tone mode, two-level modulation mode, and linear sweep mode can be enabled on either channel and in any combination simultaneously. Both channels can perform four-level modulation simultaneously. Either channel can perform eight-level or 16-level modulation. The other channel can only be in single-tone mode. The RU/RD function can be used on both channels in single-tone mode. See the Output Amplitude Control Mode section for the RU/RD function. When Profile Pin P2 and Profile Pin P3 are used for RU/RD, either channel can perform two-level modulation with RU/RD or both channels can perform linear frequency or phase sweep with RU/RD. When Profile Pin P3 is used for RU/RD, either channel can be used in eight-level modulation with RU/RD. The other channel can only be in single-tone mode. When SDIO_1, SDIO_2, and SDIO_3 pins are used for RU/RD, either or both channels can perform two-level modulation with RU/RD. If one channel is not in two-level modulation, it can only be in single-tone mode. When the SDIO_1, SDIO_2, and SDIO_3 pins are used for RU/RD, either or both channels can perform four-level modulation with RU/RD. If one channel is not in four-level modulation, it can only be in single-tone mode. When the SDIO_1, SDIO_2, and SDIO_3 pins are used for RU/RD, either channel can perform eight-level modulation with RU/RD. The other channel can only be in single-tone mode. When the SDIO_1, SDIO_2, and SDIO_3 pins are used for RU/RD, either channel can perform 16-level modulation with RU/RD. The other channel can only be in single-tone mode. Amplitude modulation, linear amplitude sweep modes, and the RU/RD function cannot operate simultaneously, but frequency and phase modulation can operate simultaneously with the RU/RD function. POWER SUPPLIES The AVDD and DVDD supply pins provide power to the DDS core and supporting analog circuitry. These pins connect to a 1.8 V nominal power supply. The DVDD_I/O pin connects to a 3.3 V nominal power supply. All digital inputs are 3.3 V logic except for the CLK_MODE_SEL input. CLK_MODE_SEL (Pin 24) is an analog input and should be operated by 1.8 V logic. SINGLE-TONE MODE Single-tone mode is the default mode of operation after a master reset signal. In this mode, both DDS channels share a common address location for the frequency tuning word (Register 0x04) and phase offset word (Register 0x05). Channel enable bits are provided in combination with these shared addresses. As a result, the frequency tuning word and/or phase offset word can be independently programmed between channels (see the following Step 1 through Step 5). The channel enable bits do not require an I/O update to enable or disable a channel. See the Register Maps and Bit Descriptions section for a description of the channel enable bits in the channel select register (CSR, Register 0x00). The channel enable bits are enabled or disabled immediately after the CSR data byte is written. Address sharing enables channels to be written simultaneously, if desired. The default state enables all channel enable bits. Therefore, the frequency tuning word and/or phase offset word is common to all channels but written only once through the serial I/O port. The following steps present a basic protocol to program a different frequency tuning word and/or phase offset word for each channel using the channel enable bits. 1. 2. 3. 4. 5. Rev. C | Page 19 of 44 Power up the DUT and issue a master reset. A master reset places the part in single-tone mode and singlebit mode for serial programming operations (refer to the Serial I/O Modes of Operation section). Frequency tuning words and phase offset words default to 0 at this point. Enable only one channel enable bit (Register 0x00) and disable the other channel enable bit. Using the serial I/O port, program the desired frequency tuning word (Register 0x04) and/or the phase offset word (Register 0x05) for the enabled channel. Repeat Step 2 and Step 3 for each channel. Send an I/O update signal. After an I/O update, all channels should output their programmed frequency and/or phase offset values. AD9958 Data Sheet REFERENCE CLOCK MODES The AD9958 supports multiple reference clock configurations to generate the internal system clock. As an alternative to clocking the part directly with a high frequency clock source, the system clock can be generated using the internal, PLL-based reference clock multiplier. An on-chip oscillator circuit is also available for providing a low frequency reference signal by connecting a crystal to the clock input pins. Enabling these features allows the part to operate with a low frequency clock source and still provide a high update rate for the DDS and DAC. However, using the clock multiplier changes the output phase noise characteristics. For best phase noise performance, a clean, stable clock with a high slew is required (see Figure 17 and Figure 18). Enabling the PLL allows multiplication of the reference clock frequency from 4× to 20×, in integer steps. The PLL multiplication value is represented by a 5-bit multiplier value. These bits are located in Function Register 1 (FR1, Register 0x01), Bits[22:18] (see the Register Maps and Bit Descriptions section). When FR1[22:18] is programmed with values ranging from 4 to 20 (decimal), the clock multiplier is enabled. The integer value in the register represents the multiplication factor. The system clock rate with the clock multiplier enabled is equal to the reference clock rate multiplied by the multiplication factor. If FR1[22:18] is programmed with a value less than 4 or greater than 20, the clock multiplier is disabled and the multiplication factor is effectively 1. Whenever the PLL clock multiplier is enabled or the multiplication value is changed, time should be allowed to lock the PLL (typically 1 ms). Note that the output frequency of the PLL is restricted to a frequency range of 100 MHz to 500 MHz. However, there is a VCO gain control bit that must be used appropriately. The VCO gain control bit defines two ranges (low/high) of frequency output. The VCO gain control bit defaults to low (see Table 1 for details). Enabling the on-chip oscillator for crystal operation is performed by driving CLK_MODE_SEL (Pin 24) to logic high (1.8 V logic). With the on-chip oscillator enabled, connection of an external crystal to the REF_CLK and REF_CLK inputs is made, producing a low frequency reference clock. The frequency of the crystal must be in the range of 20 MHz to 30 MHz. Table 4 summarizes the clock modes of operation. See Table 1 for more details. Reference Clock Input Circuitry The reference clock input circuitry has two modes of operation controlled by the logic state of Pin 24 (CLK_MODE_SEL). The first mode (logic low) configures as an input buffer. In this mode, the reference clock must be ac-coupled to the input due to internal dc biasing. This mode supports either differential or single-ended configurations. If single-ended mode is chosen, the complementary reference clock input (Pin 22) should be decoupled to AVDD or AGND via a 0.1 µF capacitor. Figure 33 to Figure 35 exemplify typical reference clock configurations for the AD9958. 1:1 BALUN 0.1µF 50Ω REFCLK SOURCE 0.1µF REF_CLK PIN 23 REF_CLK PIN 22 Figure 33. Differential Coupling from Single-Ended Source The reference clock inputs can also support an LVPECL or PECL driver as the reference clock source. 0.1µF LVPECL/ PECL DRIVER REF_CLK PIN 23 TERMINATION 0.1µF REF_CLK PIN 22 05252-118 In single-tone mode, the AD9958 offers matched pipeline delay to the DAC input for all frequency, phase, and amplitude changes. This avoids having to deal with different pipeline delays between the three input ports for such applications. The feature is enabled by asserting the matched pipe delays active bit found in the channel function register (CFR, Register 0x03). This feature is available in single-tone mode only. The charge pump current in the PLL defaults to 75 µA. This setting typically produces the best phase noise characteristics. Increasing the charge pump current may degrade phase noise, but it decreases the lock time and changes the loop bandwidth. 05252-117 Single-Tone Mode—Matched Pipeline Delay Figure 34. Differential Clock Source Hook-Up The second mode of operation (Pin 24 = logic high = 1.8 V) provides an internal oscillator for crystal operation. In this mode, both clock inputs are dc-coupled via the crystal leads and are bypassed. The range of crystal frequencies supported is from 20 MHz to 30 MHz. Figure 35 shows the configuration for using a crystal. Table 4. Clock Configuration CLK_MODE_SEL, Pin 24 High = 1.8 V Logic High = 1.8 V Logic Low Low FR1[22:18] PLL Divider Ratio = M 4 ≤ M ≤ 20 M < 4 or M > 20 4 ≤ M ≤ 20 M < 4 or M > 20 Crystal Oscillator Enabled Yes Yes No No Rev. C | Page 20 of 44 System Clock (fSYSCLK) fSYSCLK = fOSC × M fSYSCLK = fOSC fSYSCLK = fREFCLK × M fSYSCLK = fREFCLK Min/Max Freq. Range (MHz) 100 < fSYSCLK < 500 20 < fSYSCLK < 30 100 < fSYSCLK < 500 0 < fSYSCLK < 500 Data Sheet AD9958 39pF 25MHz XTAL When FR1[6] = 1 and the PWR_DWN_CTL input pin is high, the AD9958 is put into full power-down mode. In this mode, all functions are powered down. This includes the DAC and PLL, which take a significant amount of time to power up. When the PLL is bypassed, the PLL is shut down to conserve power. REF_CLK PIN 23 39pF 05252-119 REF_CLK PIN 22 Figure 35. Crystal Input Configuration SCALABLE DAC REFERENCE CURRENT CONTROL MODE RSET is common to all four DACs. As a result, the full-scale currents are equal by default. The scalable DAC reference can be used to set the full-scale current of each DAC independent from one another. This is accomplished by using the register bits CFR[9:8]. Table 5 shows how each DAC can be individually scaled for independent channel control. This scaling provides for binary attenuation. Table 5. DAC Full-Scale Current Control CFR[9:8] 11 01 10 00 LSB Current State Full scale Half scale Quarter scale Eighth scale POWER-DOWN FUNCTIONS The AD9958 supports an externally controlled power-down feature and the more common software programmable powerdown bits found in previous Analog Devices DDS products. The software control power-down allows the input clock circuitry, the DAC, and the digital logic (for each separate channel) to be individually powered down via unique control bits (CFR[7:6]). These bits are not active when the externally controlled powerdown pin (PWR_DWN_CTL) is high. When the input pin, PWR_DWN_CTL, is high, the AD9958 enters a power-down mode based on the FR1[6] bit. When the PWR_DWN_CTL input pin is low, the external power-down control is inactive. When FR1[6] = 0 and the PWR_DWN_CTL input pin is high, the AD9958 is put into a fast recovery power-down mode. In this mode, the digital logic and the DAC digital logic are powered down. The DAC bias circuitry, PLL, oscillator, and clock input circuitry are not powered down. When the PWR_DWN_CTL input pin is high, the individual power-down bits (CFR[7:6]) and (FR1[7]) are invalid (don’t care) and unused. When the PWR_DWN_CTL input pin is low, the individual power-down bits control the power-down modes of operation. Note that the power-down signals are all designed such that Logic 1 indicates the low power mode and Logic 0 indicates the powered-up mode. MODULATION MODE The AD9958 can perform 2-/4-/8-/16-level modulation of frequency, phase, or amplitude. Modulation is achieved by applying data to the profile pins. Each channel can be programmed separately, but the ability to modulate multiple channels simultaneously is constrained by the limited number of profile pins. For instance, 16-level modulation uses all four profile pins, which inhibits modulation for the remaining channel. In addition, the AD9958 has the ability to ramp up or ramp down the output amplitude before, during, or after a modulation (FSK, PSK only) sequence. This is performed by using the 10-bit output scalar. If the RU/RD feature is desired, unused profile pins or unused SDIO_1/SDIO_2/SDIO_3 pins can be configured to initiate the operation. See the Output Amplitude Control Mode section for more details of the RU/RD feature. In modulation mode, each channel has its own set of control bits to determine the type (frequency, phase, or amplitude) of modulation. Each channel has 16 profile (channel word) registers for flexibility. Register 0x0A through Register 0x18 are profile registers for modulation of frequency, phase, or amplitude. Register 0x04, Register 0x05, and Register 0x06 are dedicated registers for frequency, phase, and amplitude, respectively. These registers contain the first frequency, phase offset, and amplitude word. Frequency modulation has 32-bit resolution, phase modulation is 14 bits, and amplitude is 10 bits. When modulating phase or amplitude, the word value must be MSB aligned in the profile (channel word) registers and the unused bits are don’t care bits. Rev. C | Page 21 of 44 AD9958 Data Sheet In modulation mode, the amplitude frequency phase (AFP) select bits (CFR[23:22]) and modulation level bits (FR1[9:8]) are programmed to configure the modulation type and level (see Table 6 and Table 7). Note that the linear sweep enable bit must be set to Logic 0 in direct modulation mode. If the profile pins are used for RU/RD, Logic 0 is for ramp-up and Logic 1 is for ramp-down. Because of the two channels and limited data pins, it is necessary to assign the profile pins and/or SDIO_1, SDIO_2, and SDIO_3 pins to a dedicated channel. This is controlled by the profile pin configuration (PPC) bits (FR1[14:12]). Each of the following modulation descriptions incorporates data pin assignments. Table 6. Modulation Type Configuration AFP Select (CFR[23:22]) Linear Sweep Enable (CFR[14]) Description 00 01 10 11 X 0 0 0 Modulation disabled Amplitude modulation Frequency modulation Phase modulation Two-Level Modulation—No RU/RD The modulation level bits (FR1[9:8]) are set to 00 (two-level). The AFP select bits (CFR[23:22]) are set to the desired modulation type. The RU/RD bits (FR1[11:10]) and the linear sweep enable bit (CFR[14]) are disabled. Table 9 displays how the profile pins and channels are assigned. Table 7. Modulation Level Selection Modulation Level (FR1[9:8]) Description 00 01 10 11 Two-level modulation Four-level modulation Eight-level modulation 16-level modulation As shown in Table 9, only Profile Pin P2 can be used to modulate Channel 0. If frequency modulation is selected and Profile Pin P2 is Logic 0, Channel Frequency Tuning Word 0 (Register 0x04) is chosen; if Profile Pin P2 is Logic 1, Channel Word 1 (Register 0x0A) is chosen. When modulating, the RU/RD function can be limited based on pins available for controlling the feature. The SDIO_x pins are for RU/RD only, not for modulation. Four-Level Modulation—No RU/RD The modulation level bits are set to 01 (four-level). The AFP select bits (CFR[23:22]) are set to the desired modulation type. The RU/RD bits (FR1[11:10]) and the linear sweep enable bit (CFR[14]) are disabled. Table 10 displays how the profile pins and channels are assigned to each other. Table 8. RU/RD Profile Pin Assignments Ramp-Up/Ramp-Down (RU/RD) (FR1[11:10]) 00 01 10 11 Description RU/RD disabled Only Profile Pin P2 and Profile Pin P3 available for RU/RD operation Only Profile Pin P3 available for RU/RD operation Only SDIO_1, SDIO_2, and SDIO_3 pins available for RU/RD operation; this forces the serial I/O to be used only in 1-bit mode For the conditions in Table 10, the profile (channel word) register chosen is based on the 2-bit value presented to Profile Pins [P0:P1] or Profile Pins [P2:P3]. For example, if PPC = 101, [P0:P1] = 11, and [P2:P3] = 01, then the contents of the Channel Word 3 register of Channel 0 are presented to the output of Channel 0 and the contents of the Channel Word 1 register of Channel 1 are presented to the output of Channel 1. Table 9. Profile Pin Channel Assignments Profile Pin Configuration (PPC) (FR1[14:12]) XXX P0 N/A P1 N/A P2 CH0 P3 CH1 Description Two-level modulation, both channels, no RU/RD P1 CH0 P2 CH1 P3 CH1 Description Four-level modulation on CH0 and CH1, no RU/RD Table 10. Profile Pin and Channel Assignments Profile Pin Configuration (PPC) (FR1[14:12]) 101 P0 CH0 Rev. C | Page 22 of 44 Data Sheet AD9958 Eight-Level Modulation—No RU/RD For the conditions in Table 12, the profile register chosen is based on the 4-bit value presented to Profile Pins [P0:P3]. For example, if PPC = X11 and [P0:P3] = 1110, the contents of the Channel Word 14 register of Channel 1 is presented to the output of Channel 1. The modulation level bits (FR1[9:8]) are set to 10 (eight-level). The AFP select bits (CFR[23:22]) are set to a nonzero value. The RU/RD bits (FR1[11:10]) and the linear sweep enable bit (CFR[14]) are disabled. Note that the AFP select bits of the other channel not being used must be set to 00. Table 11 shows the assignment of profile pins and channels. Two-Level Modulation Using Profile Pins for RU/RD When the RU/RD bits = 01, Profile Pin P2 and Profile Pin P3 are available for RU/RD. Note that only a modulation level of two is available in this mode. See Table 13 for available pin assignments. For the condition in Table 11, the choice of channel word registers is based on the 3-bit value presented to Profile Pins [P0:P2]. For example, if PPC = X10 and [P0:P2] = 111, the contents of the Channel Word 7 register of Channel 0 are presented to the output Channel 0. Eight-Level Modulation Using a Profile Pin for RU/RD When the RU/RD bits = 10, Profile Pin P3 is available for RU/RD. Note that only a modulation level of eight is available in this mode. See Table 14 for available pin assignments. 16-Level Modulation—No RU/RD The modulation level bits (FR1[9:8]) are set to 11 (16-level). The AFP select bits (CFR[23:22]) are set to the desired modulation type. The RU/RD bits (FR1[11:10]) and the linear sweep enable bit (CFR[14]) are disabled. The AFP select bits of the other channel not being used must be set to 00. Table 12 displays how the profile pins and channels are assigned. Table 11. Profile Pin and Channel Assignments for Eight-Level Modulation (No RU/RD) Profile Pin Config. (PPC) (FR1[14:12]) X10 X11 P0 CH0 CH1 P1 CH0 CH1 P2 CH0 CH1 P3 X X Description Eight-level modulation on CH0, no RU/RD Eight-level modulation on CH1, no RU/RD Table 12. Profile Pin and Channel Assignments for 16-Level Modulation (No RU/RD) Profile Pin Config. (PPC) (FR1[14:12]) X10 X11 P0 CH0 CH1 P1 CH0 CH1 P2 CH0 CH1 P3 CH0 CH1 Description 16-level modulation on CH0, no RU/RD 16-level modulation on CH1, no RU/RD Table 13. Profile Pin and Channel Assignments for Two-Level Modulation (RU/RD Enabled) Profile Pin Config. (PPC) (FR1[14:12]) 101 P0 CH0 P1 CH1 P2 CH0 RU/RD P3 CH1 RU/RD Description Two-level modulation on CH0 and CH1 with RU/RD Table 14. Profile Pin and Channel Assignments for Eight-Level Modulation (RU/RD Enabled) Profile Pin Config. (PPC) (FR1[14:12]) X10 X11 P0 CH0 CH1 P1 CH0 CH1 P2 CH0 CH1 P3 CH0 RU/RD CH1 RU/RD Rev. C | Page 23 of 44 Description Eight-level modulation on CH0 with RU/RD Eight-level modulation on CH1 with RU/RD AD9958 Data Sheet MODULATION USING SDIO_x PINS FOR RU/RD For RU/RD bits = 11, the SDIO_1, SDIO_2, and SDIO_3 pins are available for RU/RD. In this mode, modulation levels of 2, 4, and 16 are available. Note that the serial I/O port can be used only in 1-bit serial mode. Two-Level Modulation Using SDIO Pins for RU/RD Table 15. Profile Pin and Channel Assignments in Two-Level Modulation (RU/RD Enabled) Profile Pin Config. (PPC) (FR1[14:12]) XXX P0 N/A P1 N/A P2 CH0 P3 CH1 For the configuration in Table 15, each profile pin is dedicated to a specific channel. In this case, the SDIO_x pins can be used for the RU/RD function, as described in Table 16. Four-Level Modulation Using SDIO Pins for RU/RD For RU/RD bits = 11 (the SDIO_1 and SDIO_2 pins are available for RU/RD), the modulation level is set to 4. See Table 17 for pin assignments, including SDIO_x pin assignments. For the configuration shown in Table 17, the profile (channel word) register is chosen based on the 2-bit value presented to Profile Pins [P1:P2] or [P3:P4]. For example, if PPC = 101, [P0:P1] = 11, and [P2:P3] = 01, the contents of the Channel Word 3 register of Channel 0 are presented to the output of Channel 0 and the contents of the Channel Word 1 register of Channel 1 are presented to the output of Channel 1. SDIO_1 and SDIO_2 provide the RU/RD function. 16-Level Modulation Using SDIO Pins for RU/RD The RU/RD bits = 11 (SDIO_1 available for RU/RD), and the level is set to 16. See the pin assignments shown in Table 18. For the configuration shown in Table 18, the profile (channel word) register is chosen based on the 4-bit value presented to Profile Pins [P0:P3]. For example, if PPC = X10 and [P0:P3] = 1101, then the contents of the Channel Word 13 register of Channel 0 is presented to the output of Channel 0. The SDIO_1 pin provides the RU/RD function. Table 16. Channel and SDIO_1/SDIO_2/SDIO_3 Pin Assignments for RU/RD Operation SDIO_1 1 1 1 1 SDIO_2 0 0 1 1 SDIO_3 0 1 0 1 Description Triggers the ramp-up function for CH0 Triggers the ramp-down function for CH0 Triggers the ramp-up function for CH1 Triggers the ramp-down function for CH1 Table 17. Channel and Profile Pin Assignments, Including SDIO_1/SDIO_2/SDIO_3 Pin Assignments for RU/RD Operation Profile Pin Configuration (PPC) (FR1[14:12]) 101 P0 CH0 P1 CH0 P2 CH1 P3 CH1 SDIO_1 CH0 RU/RD SDIO_2 CH1 RU/RD SDIO_3 N/A Table 18. Channel and Profile Pin Assignments, Including SDIO_1 Pin Assignments for RU/RD Operation Profile Pin Configuration (PPC) (FR1[14:12]) X10 X11 P0 CH0 CH1 P1 CH0 CH1 P2 CH0 CH1 Rev. C | Page 24 of 44 P3 CH0 CH1 SDIO_1 CH0 RU/RD CH1 RU/RD SDIO_2 N/A N/A SDIO_3 N/A N/A Data Sheet AD9958 Setting the Slope of the Linear Sweep Linear sweep mode enables the user to sweep frequency, phase, or amplitude from a starting point (S0) to an endpoint (E0). The purpose of linear sweep mode is to provide better bandwidth containment compared to direct modulation by replacing greater instantaneous changes with more gradual, user-defined changes between S0 and E0. The slope of the linear sweep is set by the intermediate step size (delta-tuning word) between S0 and E0 and the time spent (sweep ramp rate word) at each step. The resolution of the delta-tuning word is 32 bits for frequency, 14 bits for phase, and 10 bits for amplitude. The resolution for the delta ramp rate word is eight bits. In linear sweep mode, S0 is loaded into the Channel Word 0 register (S0 is represented by one of three registers: Register 0x04, Register 0x05, or Register 0x06, depending on the type of sweep) and E0 is always loaded into Channel Word 1 (Register 0x0A). If E0 is configured for frequency sweep, the resolution is 32 bits, phase sweep is 14 bits, and amplitude sweep is 10 bits. When sweeping phase or amplitude, the word value must be MSB aligned in the Channel Word 1 register. The unused bits are don’t care bits. The profile pins are used to trigger and control the direction of the linear sweep for frequency, phase, and amplitude. All channels can be programmed separately for a linear sweep. In linear sweep mode, Profile Pin P2 is dedicated to Channel 0. Profile Pin P3 is dedicated to Channel 1. In linear sweep, each channel is assigned a rising delta word (RDW, Register 0x08) and a rising sweep ramp rate word (RSRR, Register 0x07). These settings apply when sweeping up toward E0. The falling delta word (FDW, Register 0x09) and falling sweep ramp rate (FSRR, Register 0x07) apply when sweeping down toward S0. Figure 36 displays a linear sweep up and then down using a profile pin. Note that the linear sweep no-dwell bit is disabled; otherwise, the sweep accumulator returns to 0 upon reaching E0. E0 Table 19. Linear Sweep Parameter to Sweep AFP Select (CFR[23:22]) 00 01 10 11 Linear Sweep Enable (CFR[14]) 1 1 1 1 ∆f,p,a ∆f,p,a RSRR ∆t FSRR ∆t PROFILE PIN TIME Figure 36. Linear Sweep Parameters For a piecemeal or a nonlinear transition between S0 and E0, the delta-tuning words and ramp rate words can be reprogrammed during the transition to produce the desired response. The formulas for calculating the step size of RDW or FDW for delta frequency, delta phase, or delta amplitude are as follows: Description N/A Amplitude sweep Frequency sweep Phase sweep RDW f   32   SYSCLK (Hz)  2  RDW ΔΦ   14   360   2  RDW a   10   1024 (DAC full-scale current)  2  Table 20. Modulation Level Assignments Modulation Level (FR1[9:8]) 00 (Required in Linear Sweep) 01 10 11 FDW S0 To enable linear sweep mode for a particular channel, the AFP select bits (CFR[23:22]), the modulation level bits (FR1[9:8]), and the linear sweep enable bit (CFR[14]) are programmed. The AFP select bits determine the type of linear sweep to be performed. The modulation level bits must be set to 00 (twolevel) for that specific channel (see Table 19 and Table 20) RDW 05252-120 The AD9958 has the ability to ramp up or ramp down (RU/RD) the output amplitude (using the 10-bit output scalar) before and after a linear sweep. If the RU/RD feature is desired, unused profile pins or unused SDIO_1/SDIO_2/SDIO_3 pins can be configured for the RU/RD operation. (FREQUENCY/PHASE/AMPLITUDE) LINEAR SWEEP LINEAR SWEEP MODE Description Two-level modulation Four-level modulation Eight-level modulation 16-level modulation The formula for calculating delta time from RSRR or FSRR is t  RSRR  1/ SYNC _ CLK At 500 MSPS operation (SYNC_CLK = 125 MHz), the maximum time interval between steps is 1/125 MHz × 256 = 2.048 μs. The minimum time interval is (1/125 MHz) × 1 = 8.0 ns. The sweep ramp rate block (timer) consists of a loadable 8-bit down counter that continuously counts down from the loaded value to 1. When the ramp rate timer equals 1, the proper ramp rate value is loaded and the counter begins counting down to 1 again. Rev. C | Page 25 of 44 AD9958 Data Sheet This load and countdown operation continues for as long as the timer is enabled. However, the count can be reloaded before reaching 1 by either of the following two methods: When the profile pin transitions from high to low, the FDW is applied to the input of the sweep accumulator and the FSRR bits are loaded into the sweep rate timer.  The FDW accumulates at the rate given by the falling sweep ramp rate (FSRR) until the output is equal to the CFTW0 register (Register 0x04) value. The sweep is then complete, and the output is held constant in frequency.  Method 1 is to change the profile pin. When the profile pin changes from Logic 0 to Logic 1, the rising sweep ramp rate (RSRR) register value is loaded into the ramp rate timer, which then proceeds to count down as normal. When the profile pin changes from Logic 1 to Logic 0, the falling sweep ramp rate (FSRR) register value is loaded into the ramp rate timer, which then proceeds to count down as normal. Method 2 is to set the CFR[13] bit and issue an I/O update. If linear sweep is enabled and CFR[13] is set, the ramp rate timer loads the value determined by the profile pin. If the profile pin is high, the ramp rate timer loads the RSRR; if the profile pin is low, the ramp rate timer loads FSRR. See Figure 37 for the linear sweep block diagram. Figure 39 depicts a frequency sweep with no-dwell mode disabled. In this mode, the output follows the state of the profile pin. A phase or amplitude sweep works in the same manner. LINEAR SWEEP NO-DWELL MODE If the linear sweep no-dwell bit is set (CFR[15]), the rising sweep is started in an identical manner to the dwell linear sweep mode; that is, upon detecting Logic 1 on the profile input pin, the rising sweep action is initiated. The word continues to sweep up at the rate set by the rising sweep ramp rate at the resolution set by the rising delta word until it reaches the terminal value. Upon reaching the terminal value, the output immediately reverts to the starting point and remains until Logic 1 is detected on the profile pin. Frequency Linear Sweep Example: AFP Bits = 10 In the following example, the modulation level bits (FR1[9:8]) = 00, the linear sweep enable bit (CFR[14]) = 1, and the linear sweep no-dwell bit (CFR[15]) = 0. In linear sweep mode, when the profile pin transitions from low to high, the RDW is applied to the input of the sweep accumulator and the RSRR register is loaded into the sweep rate timer. Figure 38 shows an example of the no-dwell mode. The points labeled A indicate where a rising edge is detected on the profile pin, and the points labeled B indicate where the AD9958 has determined that the output has reached E0 and reverts to S0. The falling sweep ramp rate bits (LSRR[15:8]) and the falling delta word bits (FDW[31:0]) are unused in this mode. The RDW accumulates at the rate given by the rising sweep ramp rate (RSRR) bits until the output is equal to the CW1 register value. The sweep is then complete, and the output is held constant in frequency. SWEEP ACCUMULATOR 0 FDW 0 32 MUX RDW 0 32 MUX 32 Z–1 32 32 0 1 0 1 SWEEP ADDER MUX 0 1 MUX 1 PROFILE PIN 32 CFTW0 RAMP RATE TIMER: 8-BIT LOADABLE DOWN COUNTER ACCUMULATOR RESET LOGIC 8 RATE TIME LOAD CONTROL LOGIC MUX FSRR PROFILE PIN 32 CW1 1 05252-121 0 LIMIT LOGIC TO KEEP SWEEP BETWEEN S0 AND E0 RSRR Figure 37. Linear Sweep Block Diagram (Frequency Sweep) Rev. C | Page 26 of 44 Data Sheet AD9958 fOUT B FTW1 A FTW0 B B A A TIME SINGLE-TONE MODE P2 = 1 P2 = 0 P2 = 1 P2 = 0 P2 = 1 05252-147 P2 = 0 LINEAR SWEEP MODE ENABLE—NO-DWELL BIT SET Figure 38. Channel 0 in Linear Sweep Mode (No-Dwell Enabled) fOUT B FTW1 A FTW0 TIME P2 = 0 LINEAR SWEEP MODE P2 = 1 P2 = 0 AT POINT A: LOAD RISING RAMP RATE REGISTER, APPLY RDW AT POINT B: LOAD FALLING RAMP RATE REGISTER, APPLY FDW 05252-148 SINGLE-TONE MODE Figure 39. Channel 0 in Linear Sweep Mode (No-Dwell Disabled) Continuous Clear Bits SWEEP AND PHASE ACCUMULATOR CLEARING FUNCTIONS The AD9958 allows two different clearing functions. The first is a continuous zeroing of the sweep logic and phase accumulator (clear and hold). The second is a clear and release or automatic zeroing function. CFR[4] is the autoclear sweep accumulator bit and CFR[2] is the autoclear phase accumulator bit. The continuous clear bits are located in CFR, where CFR[3] clears the sweep accumulator and CFR[1] clears the phase accumulator. The continuous clear bits are static control signals that, when active high, hold the respective accumulator at 0 while the bit is active. When the bit goes low, the respective accumulator is allowed to operate. Clear and Release Bits The autoclear sweep accumulator bit, when set, clears and releases the sweep accumulator upon an I/O update or a change in the profile input pins. The autoclear phase accumulator bit, when set, clears and releases the phase accumulator upon an I/O update or a change in the profile pins. The automatic clearing function is repeated for every subsequent I/O update or change in profile pins until the clear and release bits are reset via the serial port. Rev. C | Page 27 of 44 AD9958 Data Sheet OUTPUT AMPLITUDE CONTROL MODE A special feature of this mode is that the maximum output amplitude allowed is limited by the contents of the amplitude scale factor (ACR[9:0]). This allows the user to ramp to a value less than full scale. The 10-bit scale factor (multiplier) controls the ramp-up and ramp-down (RU/RD) time of an on/off emission from the DAC. In burst transmissions of digital data, it reduces the adverse spectral impact of abrupt bursts of data. The multiplier can be bypassed by clearing the amplitude multiplier enable bit (ACR[12] = 0). Ramp Rate Timer Automatic and manual RU/RD modes are supported. The automatic mode generates a zero-scale up to a full-scale (10 bits) linear ramp at a rate determined by ACR (Register 0x06). The start and direction of the ramp can be controlled by either the profile pins or the SDIO_1/SDIO_2/SDIO_3 pins. The ramp rate timer is a loadable down counter that generates the clock signal to the 10-bit counter that generates the internal scale factor. The ramp rate timer is loaded with the value of ACR[23:16] each time the counter reaches 1 (decimal). This load and countdown operation continues for as long as the timer is enabled unless the timer is forced to load before reaching a count of 1. Manual mode allows the user to directly control the output amplitude by manually writing to the amplitude scale factor value in the ACR (Register 0x06). Manual mode is enabled by setting ACR[12] = 1 and ACR[11] = 0. If the load ARR at I/O_UPDATE bit (ACR[10]) is set, the ramp rate timer is loaded at an I/O update, a change in profile input, or upon reaching a value of 1. The ramp timer can be loaded before reaching a count of 1 by three methods. Automatic RU/RD Mode Operation • Automatic RU/RD mode is active when both ACR[12] and ACR[11] are set. When automatic RU/RD is enabled, the scale factor is internally generated and applied to the multiplier input port for scaling the output. The scale factor is the output of a 10-bit counter that increments/decrements at a rate set by the 8-bit output ramp rate register. The scale factor increments if the external pin is high and decrements if the pin is low. The internally generated scale factor step size is controlled by ACR[15:14]. Table 21 describes the increment/decrement step size of the internally generated scale factor per ACR[15:14]. Table 21. Increment/Decrement Step Size Assignments Increment/Decrement Step Size (ACR [15:14]) 00 01 10 11 • • In the first method, the profile pins or the SDIO_1/ SDIO_2/SDIO_3 pins are changed. When the control signal changes state, the ACR value is loaded into the ramp rate timer, which then proceeds to count down as normal. In the second method, the load ARR at I/O_UPDATE bit (ACR[10]) is set, and an I/O update is issued. The third method is to change from inactive automatic RU/RD mode to active automatic RU/RD mode. RU/RD Pin-to-Channel Assignment When all four channels are in single-tone mode, the profile pins are used for RU/RD operation. When linear sweep and RU/RD are activated, the SDIO_1/ SDIO_2/SDIO_3 pins are used for RU/RD operation. Size 1 2 4 8 In modulation mode, refer to the Modulation Mode section for pin assignments. Table 22. Profile Pin Assignments for RU/RD Operation Profile Pin P2 P3 RU/RD Operation CH0 CH1 Table 23. Channel Assignments of SDIO_1/SDIO_2/SDIO_3 Pins for RU/RD Operation Linear Sweep and RU/RD Modes Enabled Simultaneously Enable for CH0 Enable for CH0 Enable for CH1 Enable for CH1 SDIO_1 1 1 1 1 SDIO_2 0 0 1 1 SDIO_3 0 1 0 1 Rev. C | Page 28 of 44 Ramp-Up/Ramp-Down Control Signal Assignment Ramp-up function for CH0 Ramp-down function for CH0 Ramp-up function for CH1 Ramp-down function for CH1 Data Sheet AD9958 SYNCHRONIZING MULTIPLE AD9958 DEVICES The AD9958 allows easy synchronization of multiple AD9958 devices. At power-up, the phase of SYNC_CLK can be offset between multiple devices. To correct for the offset and align the SYNC_CLK edges, there are three methods (one automatic mode and two manual modes) of synchronizing the SYNC_CLK edges. These modes force the internal state machines of multiple devices to a known state, which aligns the SYNC_CLK edges. In addition, the user must send a coincident I/O_UPDATE to multiple devices to maintain synchronization. Any mismatch in REF_CLK phase between devices results in a corresponding phase mismatch on the SYNC_CLK edges. AUTOMATIC MODE SYNCHRONIZATION In automatic mode, multiple part synchronization is achieved by connecting the SYNC_OUT pin on the master device to the SYNC_IN pins of the slave devices. Devices are configured as master or slave through programming bits, accessible via the serial port. A configuration for synchronizing multiple AD9958 devices in automatic mode is shown in the Application Circuits section. In this configuration, the AD9510 provides coincident REF_CLK and SYNC_OUT signals to all devices. Operation The first step is to program the master and slave devices for their respective roles and then write the auto sync enable bit (FR2[7] = 1. Enabling the master device is performed by writing its multidevice sync master enable bit in Function Register 2 (FR2[6]) = 1. This causes the SYNC_OUT of the master device to output a pulse that has a pulse width equal to one system clock period and a frequency equal to one-fourth of the system clock frequency. Enabling devices as slaves is performed by writing FR2[6] = 0. In automatic synchronizing mode, the slave devices sample SYNC_OUT pulses from the master device on the SYNC_IN of the slave devices, and a comparison of all state machines is made by the autosynchronization circuitry. If the slave devices state machines are not identical to the master, the slave devices state machines are stalled for one system clock cycle. This procedure synchronizes the slave devices within three SYNC_CLK periods. Delay Time Between SYNC_OUT and SYNC_IN When the delay between SYNC_OUT and SYNC_IN exceeds one system clock period, the system clock offset bits (FR2[1:0]) are used to compensate. The default state of these bits is 00, which implies that the SYNC_OUT of the master and the SYNC_IN of the slave have a propagation delay of less than one system clock period. If the propagation time is greater than one system clock period, the time should be measured and the appropriate offset programmed. Table 24 describes the delays required per system clock offset value. Table 24. System Clock Offset (Delay) Assignments System Clock Offset (FR2[1:0]) 00 01 10 11 SYNC_OUT/SYNC_IN Propagation Delay 0 ≤ delay ≤ 1 1 ≤ delay ≤ 2 2 ≤ delay ≤ 3 3 ≤ delay ≤ 4 Automatic Synchronization Status Bits If a slave device falls out of sync, the sync status bit is set high. The multidevice sync status bit (FR2[5]) can be read through the serial port. It is automatically cleared when read. The synchronization routine continues to operate regardless of the state of FR2[5]. FR2[5] can be masked by writing Logic 1 to the multidevice sync mask bit (FR2[4]). If FR2[5] is masked, it is held low. MANUAL SOFTWARE MODE SYNCHRONIZATION Manual software mode is enabled by setting the manual software sync bit (FR1[0]) to Logic 1 in a device. In this mode, the I/O update that writes the manual software sync bit to Logic 0 stalls the state machine of the clock generator for one system clock cycle. Stalling the clock generation state machine by one cycle changes the phase relationship of SYNC_CLK between devices by one system clock period (90°). Note that the user may have to repeat this process until the devices have their SYNC_CLK signals in phase. The SYNC_IN input can be left floating because it has an internal pull-up. The SYNC_OUT pin is not used. The synchronization is complete when the master and slave devices have their SYNC_CLK signals in phase. MANUAL HARDWARE MODE SYNCHRONIZATION Manual hardware mode is enabled by setting the manual hardware sync bit (FR1[1]) to Logic 1 in a device. In manual hardware synchronization mode, the SYNC_CLK stalls by one system clock cycle each time a rising edge is detected on the SYNC_IN input. Stalling the SYNC_CLK state machine by one cycle changes the phase relationship of SYNC_CLK between devices by one system clock period (90°). Note that the user may have to repeat the process until the devices have their SYNC_CLK signals in phase. The SYNC_IN input can be left floating because it has an internal pull-up. The SYNC_OUT is not used. The synchronization is complete when the master and slave devices have their SYNC_CLK signals in phase. Rev. C | Page 29 of 44 AD9958 Data Sheet If the setup time between these signals is met, then constant latency (pipeline) to the DAC output exists. For example, if repetitive changes to phase offset via the SPI port is desired, the latency of those changes to the DAC output is constant; otherwise, a time uncertainty of one SYNC_CLK period is present. I/O_UPDATE, SYNC_CLK, AND SYSTEM CLOCK RELATIONSHIPS I/O_UPDATE and SYNC_CLK are used together to transfer data from the serial I/O buffer to the active registers in the device. Data in the buffer is inactive. SYNC_CLK is a rising edge active signal. It is derived from the system clock and a divide-by-4 frequency divider. The SYNC_CLK, which is externally provided, can be used to synchronize external hardware to the AD9958 internal clocks. I/O_UPDATE initiates the start of a buffer transfer. It can be sent synchronously or asynchronously relative to the SYNC_CLK. The I/O_UPDATE is essentially oversampled by the SYNC_CLK. Therefore, I/O_UPDATE must have a minimum pulse width greater than one SYNC_CLK period. The timing diagram shown in Figure 40 depicts when data in the buffer is transferred to the active registers. SYSCLK A B SYNC_CLK I/O_UPDATE DATA IN I/O BUFFERS N N–1 N N+1 N+1 N+2 THE DEVICE REGISTERS AN I/O UPDATE AT POINT A. THE DATA IS TRANSFERRED FROM THE ASYNCHRONOUSLY LOADED I/O BUFFERS AT POINT B. Figure 40. I/O_UPDATE Transferring Data from I/O Buffer to Active Registers Rev. C | Page 30 of 44 05252-149 DATA IN REGISTERS Data Sheet AD9958 SERIAL I/O PORT Three of the four data pins (SDIO_1, SDIO_2, SDIO_3) can be used for functions other than serial I/O port operation. These pins can also be used to initiate a ramp-up or ramp-down (RU/RD) of the 10-bit amplitude output scalar. In addition, SDIO_3 can be used to provide the SYNC_I/O function that resynchronizes the serial I/O port controller if it is out of proper sequence. The maximum speed of the serial I/O port SCLK is 200 MHz, but the four data pins (SDIO_0, SDIO_1, SDIO_2, SDIO_3) can be used to further increase data throughput. The maximum data throughput using all the SDIO pins (SDIO_0, SDIO_1, SDIO_2, SDIO_3) is 800 Mbps. Note that both channels share Register 0x03 to Register 0x18, which are shown in the Register Maps and Bit Descriptions section. This address sharing enables both DDS channels to be written to simultaneously. For example, if a common frequency tuning word is desired for both channels, it can be written once through the serial I/O port to both channels. This is the default mode of operation (all channels enabled). To enable each channel to be independent, the two channel enable bits found in the channel select register (CSR, Register 0x00) must be used. For example, when accessing Function Register 1 (FR1), which is three bytes wide, Phase 2 of the I/O cycle requires that three bytes be transferred. After transferring all data bytes per the instruction byte, the communication cycle is completed for that register. At the completion of a communication cycle, the AD9958 serial port controller expects the next set of rising SCLK edges to be the instruction byte for the next communication cycle. All data written to the AD9958 is registered on the rising edge of SCLK. Data is read on the falling edge of SCLK (see Figure 43 through Figure 49). The timing specifications for Figure 41 and Figure 42 are described in Table 25. tPRE tDSU There are two phases to a serial communications cycle. Phase 1 is the instruction cycle, which writes the instruction byte into the AD9958. Each bit of the instruction byte is registered on each corresponding rising edge of SCLK. The instruction byte defines whether the upcoming data transfer is a write or read operation. The instruction byte contains the serial address of the address register. tSCLKPWL SCLK tSCLKPWH tDHLD SDIO_x Figure 41. Setup and Hold Timing for the Serial I/O Port There are effectively four sets or copies of addresses (Register 0x03 to Register 0x18) that the channel enable bits can access to provide channel independence. See the Descriptions for Control Registers section for further details of programming channels that are common to or independent from each other. To properly read back Register 0x03 to Register 0x18, the user must enable only one channel enable bit at a time. Serial operation of the AD9958 occurs at the register level, not the byte level; that is, the controller expects that all bytes contained in the register address are accessed. The SYNC_I/O function can be used to abort an I/O operation, thereby allowing fewer than all bytes to be accessed. This feature can be used to program only a part of the addressed register. Note that only completed bytes are affected. tSCLK CS 05252-123 The AD9958 serial I/O port offers multiple configurations to provide significant flexibility. The serial I/O port offers an SPIcompatible mode of operation that is virtually identical to the SPI operation found in earlier Analog Devices DDS products. The flexibility is provided by four data pins (SDIO_0, SDIO_1, SDIO_2, SDIO_3) that allow four programmable modes of serial I/O operation. Phase 2 of the I/O cycle consists of the actual data transfer (write/read) between the serial port controller and the serial port buffer. The number of bytes transferred during this phase of the communication cycle is a function of the register being accessed. The actual number of additional SCLK rising edges required for the data transfer and instruction byte depends on the number of bytes in the register and the serial I/O mode of operation. CS SCLK SDIO_x SDO (SDIO_2) tDV 05252-124 OVERVIEW Figure 42. Timing Diagram for Data Read for Serial I/O Port Table 25. Timing Specifications Parameter tPRE tSCLK tDSU tSCLKPWH tSCLKPWL tDHLD tDV Rev. C | Page 31 of 44 Min 1.0 5.0 2.2 2.2 1.6 0 12 Unit ns min ns min ns min ns min ns min ns min ns min Description CS setup time Period of serial data clock Serial data setup time Serial data clock pulse width high Serial data clock pulse width low Serial data hold time Data valid time AD9958 Data Sheet Each set of communication cycles does not require an I/O update to be issued. The I/O update transfers data from the I/O port buffer to active registers. The I/O update can be sent for each communication cycle or can be sent when all serial operations are complete. However, data is not active until an I/O update is sent, with the exception of the channel enable bits in the channel select register (CSR). These bits do not require an I/O update to be enabled. INSTRUCTION BYTE DESCRIPTION The instruction byte contains the following information: MSB LSB D7 D6 D5 D4 D3 D2 D1 D0 R/W x1 x1 A4 A3 A2 A1 A0 1 x = don’t care bit. Bit D7 of the instruction byte (R/W) determines whether a read or write data transfer occurs after the instruction byte write. A logic high indicates a read operation. A logic low indicates a write operation. Bit D4 to Bit D0 of the instruction byte determine which register is accessed during the data transfer portion of the communication cycle. The internal byte addresses are generated by the AD9958. SERIAL I/O PORT PIN DESCRIPTION this pin. The SDO function is not available in 2-bit or 4-bit serial I/O modes. SYNC_I/O The SYNC_I/O function is available in 1-bit and 2-bit modes. SDIO_3 serves as the SYNC_I/O pin when this function is active. Bits CSR[2:1] control the configuration of this pin. Otherwise, the SYNC_I/O function is used to synchronize the I/O port state machines without affecting the addressable register contents. An active high input on the SYNC_I/O (SDIO_3) pin causes the current communication cycle to abort. After SDIO_3 returns low (Logic 0), another communication cycle can begin, starting with the instruction byte write. The SYNC_I/O function is not available in 4-bit serial I/O mode. MSB/LSB TRANSFER DESCRIPTION The AD9958 serial port can support both most significant bit (MSB) first or least significant bit (LSB) first data formats. This functionality is controlled by CSR[0]. MSB first is the default mode. When CSR[0] is set high, the AD9958 serial port is in LSB first format. The instruction byte must be written in the format indicated by CSR[0], that is, if the AD9958 is in LSB first mode, the instruction byte must be written from LSB to MSB. If the AD9958 is in MSB first mode (default), the instruction byte must be written from MSB to LSB. Example Operation Serial Data Clock (SCLK) The serial data clock pin is used to synchronize data to and from the internal state machines of the AD9958. The maximum SCLK toggle frequency is 200 MHz. Chip Select (CS) To write Function Register 1 (FR1, Register 0x01) in MSB first format, apply an instruction byte of 00000001 starting with the MSB (in the following example instruction byte, the MSB is D7). From this instruction, the internal controller recognizes a write transfer of three bytes starting with the MSB, FR1[23]. Bytes are written on each consecutive rising SCLK edge until Bit 0 is transferred. When the last data bit is written, the I/O communication cycle is complete and the next byte is considered an instruction byte. The chip select pin allows more than one AD9958 device to be on the same set of serial communications lines. The chip select is an active low enable pin. SDIO_x inputs go to a high impedance state when CS is high. If CS is driven high during any communication cycle, that cycle is suspended until CS is reactivated low. The CS pin can be tied low in systems that maintain control of SCLK. D7 D6 D5 D4 D3 D2 D1 D0 Serial Data I/O (SDIO_x) 0 0 0 0 0 0 0 1 Of the four SDIO pins, only the SDIO_0 pin is a dedicated SDIO pin. SDIO_1, SDIO_2, and SDIO_3 can also be used to ramp up/ramp down the output amplitude. Bits[2:1] in the channel select register (CSR, Register 0x00) control the configuration of these pins. See the Serial I/O Modes of Operation for more information. SERIAL I/O PORT FUNCTION DESCRIPTION Serial Data Out (SDO) The SDO function is available in single-bit (3-wire) mode only. In SDO mode, data is read from the SDIO_2 pin for protocols that use separate lines for transmitting and receiving data (see Table 26 for pin configuration options). Bits[2:1] in the channel select register (CSR, Register 0x00) control the configuration of Example Instruction Byte1 MSB 1 LSB Note that the bit values are for example purposes only. To write Function Register 1 (FR1) in LSB first format, apply an instruction byte of 00000001, starting with the LSB bit (in the preceding example instruction byte, the LSB is D0). From this instruction, the internal controller recognizes a write transfer of three bytes, starting with the LSB, FR1[0]. Bytes are written on each consecutive rising SCLK edge until Bit 23 is transferred. When the last data bit is written, the I/O communication cycle is complete and the next byte is considered an instruction byte. Rev. C | Page 32 of 44 Data Sheet AD9958 SERIAL I/O MODES OF OPERATION The following are the four programmable modes of serial I/O port operation: • • • • Single-bit serial 2-wire mode (default mode) Single-bit serial 3-wire mode 2-bit serial mode 4-bit serial mode (SYNC_I/O not available) Table 26 displays the function of all six serial I/O interface pins, depending on the mode of serial I/O operation programmed. Table 26. Serial I/O Port Pin Function vs. Serial I/O Mode Pin SCLK Single-Bit Serial 2-Wire Mode Serial clock Single-Bit Serial 3-Wire Mode Serial clock 2-Bit Serial Mode Serial clock CS Chip select Chip select Chip select SDIO_0 Serial data I/O Serial data in SDIO_1 Not used for SDIO1 Not used for SDIO1 SYNC_I/O Not used for SDIO1 Serial data out (SDO) SYNC_I/O Serial data I/O Serial data I/O Not used for SDIO1 SYNC_I/O SDIO_2 SDIO_3 1 4-Bit Serial Mode Serial clock Chip select Serial data I/O Serial data I/O Serial data I/O Serial data I/O In serial mode, these pins (SDIO_0/SDIO_1/SDIO_2/SDIO_3) can be used for RU/RD operation. The two bits in the channel select register, CSR[2:1], set the serial I/O mode of operation and are defined in Table 27. Table 27. Serial I/O Mode of Operation Serial I/O Mode Select (CSR[2:1]) 00 01 10 11 Mode of Operation Single-bit serial mode (2-wire mode) Single-bit serial mode (3-wire mode) 2-bit serial mode 4-bit serial mode Single-Bit Serial (2-Wire and 3-Wire) Modes The single-bit serial mode interface allows read/write access to all registers that configure the AD9958. MSB first or LSB first transfer formats are supported. In addition, the single-bit serial mode interface port can be configured either as a single pin I/O, which allows a 2-wire interface, or as two unidirectional pins for input/output, which enable a 3-wire interface. Single-bit mode allows the use of the SYNC_I/O function. In single-bit serial mode, 2-wire interface operation, the SDIO_0 pin is the single serial data I/O pin. In single-bit serial mode 3-wire interface operation, the SDIO_0 pin is the serial data input pin and the SDIO_2 pin is the output data pin. Regardless of the number of wires used in the interface, the SDIO_3 pin is configured as an input and operates as the SYNC_I/O pin in the single-bit serial mode and 2-bit serial mode. The SDIO_1 pin is unused in this mode (see Table 26). 2-Bit Serial Mode The SPI port operation in 2-bit serial mode is identical to the SPI port operation in single-bit serial mode, except that two bits of data are registered on each rising edge of SCLK. Therefore, it only takes four clock cycles to transfer eight bits of information. The SDIO_0 pin contains the even numbered data bits using the notation D[7:0], and the SDIO_1 pin contains the odd numbered data bits. This even and odd numbered pin/data alignment is valid in both MSB and LSB first formats (see Figure 44). 4-Bit Serial Mode The SPI port in 4-bit serial mode is identical to the SPI port in single-bit serial mode, except that four bits of data are registered on each rising edge of SCLK. Therefore, it takes only two clock cycles to transfer eight bits of information. The SDIO_0 and SDIO_2 pins contain even numbered data bits using the notation D[7:0], and the SDIO_0 pin contains the LSB of the nibble. The SDIO_1 and SDIO_3 pins contain the odd numbered data bits, and the SDIO_1 pin contains the LSB of the nibble to be accessed. Note that when programming the device for 4-bit serial mode, it is important to keep the SDIO_3 pin at Logic 0 until the device is programmed out of the single-bit serial mode. Failure to do so can result in the serial I/O port controller being out of sequence. Figure 43 through Figure 45 represent write timing diagrams for each of the serial I/O modes available. Both MSB and LSB first modes are shown. LSB first bits are shown in parentheses. The clock stall low/high feature shown is not required. It is used to show that data (SDIO) must have the proper setup time relative to the rising edge of SCLK. Figure 46 through Figure 49 represent read timing diagrams for each of the serial I/O modes available. Both MSB and LSB first modes are shown. LSB first bits are shown in parentheses. The clock stall low/high feature shown is not required. It is used to show that data (SDIO) must have the proper setup time relative to the rising edge of SCLK for the instruction byte and the read data that follows the falling edge of SCLK. Rev. C | Page 33 of 44 AD9958 Data Sheet DATA TRANSFER CYCLE INSTRUCTION CYCLE CS I5 (I2) I6 (I1) D7 (D0) I0 (I7) I1 (I6) I2 (I5) I3 (I4) I4 (I3) D6 (D1) D4 (D3) D5 (D2) D3 (D4) D2 (D5) Figure 43. Single-Bit Serial Mode Write Timing—Clock Stall Low INSTRUCTION CYCLE DATA TRANSFER CYCLE CS SCLK SDIO_1 I7 (I1) I5 (I3) I3 (I5) I1 (I7) D7 (D1) D5 (D3) D3 (D5) D1 (D7) SDIO_0 I6 (I0) I4 (I2) I2 (I4) I0 (I6) D6 (D0) D4 (D2) D2 (D4) D0 (D6) 05252-126 I7 (I0) Figure 44. 2-Bit Serial Mode Write Timing—Clock Stall Low INSTRUCTION CYCLE DATA TRANSFER CYCLE CS SCLK SDIO_3 I7 (I3) I3 (I7) D7 (D3) D3 (D7) SDIO_2 I6 (I2) I2 (I6) D6 (D2) D2 (D6) SDIO_1 I5 (I1) I1 (I5) D5 (D1) D1 (D5) SDIO_0 I4 (I0) I0 (I4) D4 (D0) D0 (D4) Figure 45. 4-Bit Serial Mode Write Timing—Clock Stall Low Rev. C | Page 34 of 44 05252-127 SDIO_0 D1 (D6) D0 (D7) 05252-125 SCLK Data Sheet AD9958 DATA TRANSFER CYCLE INSTRUCTION CYCLE CS I7 (I0) SDIO_0 I6 (I1) I5 (I2) I4 (I3) I3 (I4) I2 (I5) I1 (I6) I0 (I7) D7 (D0) D6 (D1) D5 (D2) D4 (D3) D3 (D4) D2 (D5) D1 (D6) D0 (D7) 05252-128 SCLK Figure 46. Single-Bit Serial Mode (2-Wire) Read Timing—Clock Stall High DATA TRANSFER CYCLE INSTRUCTION CYCLE CS SCLK I6 (I1) I5 (I2) I4 (I3) I3 (I4) I2 (I5) I1 (I6) I0 (I7) DON'T CARE SDO D7 (D0) (SDIO_2 PIN) D6 (D1) D5 (D2) D4 (D3) D3 (D4) D2 (D5) D1 (D6) Figure 47. Single-Bit Serial Mode (3-Wire) Read Timing—Clock Stall Low INSTRUCTION CYCLE DATA TRANSFER CYCLE CS SCLK I7 (I1) I5 (I3) I3 (I5) I1 (I7) D7 (D1) D5 (D3) D3 (D5) D1 (D7) SDIO_0 I6 (I0) I4 (I2) I2 (I4) I0 (I6) D6 (D0) D4 (D2) D2 (D4) D0 (D6) 05252-130 SDIO_1 Figure 48. 2-Bit Serial Mode Read Timing—Clock Stall High INSTRUCTION CYCLE DATA TRANSFER CYCLE CS SCLK SDIO_3 I7 (I3) I3 (I7) D7 (D3) D3 (D7) SDIO_2 I6 (I2) I2 (I6) D6 (D2) D2 (I6) SDIO_1 I5 (I1) I1 (I5) D5 (D1) D1 (D5) SDIO_0 I4 (I0) I0 (I4) D4 (D0) D0 (D4) Figure 49. 4-Bit Serial Mode Read Timing—Clock Stall High Rev. C | Page 35 of 44 D0 (D7) 05252-129 I7 (I0) 05252-131 SDIO_0 AD9958 Data Sheet REGISTER MAPS AND BIT DESCRIPTIONS REGISTER MAPS Table 28. Control Register Map Register Name (Serial Address) Channel Select Register (CSR) (0x00) Function Register 1 (FR1) (0x01) Function Register 2 (FR2) (0x02) Bit Range [7:0] Bit 7 (MSB) Channel 1 enable 1 [23:16] VCO gain control [15:8] Open [7:0] Reference clock input power-down All channels autoclear sweep accumulator Auto sync enable [15:8] [7:0] Bit 6 Channel 0 enable1 Bit 5 Open 2 Bit 4 Open2 Bit 3 Must be 0 Bit 2 Bit 1 Serial I/O mode select[2:1] PLL divider ratio[22:18] Profile pin configuration (PPC)[14:12] External powerdown mode SYNC_CLK disable DAC reference power-down All channels clear wweep accumulator All channels autoclear phase accumulator All channels clear phase accumulator Multidevice sync master enable Multidevice sync status Multidevice sync mask Ramp-up/ ramp-down (RU/RD)[11:10] Open[3:2] Open[3:2] Bit 0 (LSB) LSB first Default Value 0xF0 Charge pump control[17:16] 0x00 Modulation level[9:8] 0x00 Manual software sync 0x00 Manual hardware sync Open[11:8] System clock offset[1:0] 0x00 0x00 Channel enable bits do not require an I/O update to be activated. These bits are active immediately after the byte containing the bits is written. All other bits need an I/O update to become active. The two channel enable bits shown in Table 28 are used to enable/disable any combination of the two channels. The default for both channels is enabled. In readback mode, enable one channel enable bit at a time. 2 This bit must be disabled (Logic 0) in readback mode. 1 3. In the channel select register, if the user wants two different frequencies for the two DDS channels, use the following protocol: 1. 2. 4. Enable (Logic 1) the Channel 0 enable bit, which is located in the channel select register, and disable the Channel 1 enable bit (Logic 0). Write the desired frequency tuning word for Channel 0, as described in Step 1, and then disable the Channel 0 enable bit (Logic 0). Rev. C | Page 36 of 44 Enable the Channel 1 enable bit only, located in the channel select Register. Write the desired frequency tuning word for Channel 1 in Step 3. Data Sheet AD9958 Table 29. Channel Register Map Register Name (Serial Address) Channel Function Register 1 (CFR) (0x03) Bit Range [23:16] [15:8] [7:0] Channel Frequency Tuning Word 01 (CFTW0) (0x04) Channel Phase Offset Word 01 (CPOW0) (0x05) Amplitude Control Register (ACR) (0x06) Linear Sweep Ramp Rate1 (LSRR) (0x07) LSR Rising Delta Word1 (RDW) (0x08) LSR Falling Delta Word1 (FDW) (0x09) Bit 7 (MSB) Bit 6 Amplitude freq. phase (AFP) select[23:22] Linear Linear sweep sweep enable no-dwell Digital DAC powerpowerdown down Bit 5 Load SRR at I/O_UPDATE Matched pipe delays active [31:24] [23:16] [15:8] [7:0] [15:8] [7:0] [23:16] [15:8] [7:0] [15:8] [7:0] Bit 4 Bit 3 Bit 2 Open[21:16] Open[12:11] Autoclear sweep accumulator Clear sweep accumulator Must be 0 Autoclear phase accumulator Bit 1 Bit 0 (LSB) DAC full-scale current control[9:8] Clear phase accumulator 2 Sine wave output enable Frequency Tuning Word 0[31:24] Frequency Tuning Word 0[23:16] Frequency Tuning Word 0[15:8] Frequency Tuning Word 0[7:0] Open[15:14] Increment/decrement step size[15:14] Amplitude Ramp Rate[23:16] Amplitude Ramp-up/ Load ARR at multiplier ramp-down I/O_UPDATE enable enable Amplitude scale factor[7:0] Falling sweep ramp rate (FSRR)[15:8] Rising sweep ramp rate (RSRR)[7:0] 0x03 0x02 0x00 N/A N/A N/A Phase Offset Word 0[13:8] Phase Offset Word 0[7:0] Open Default Value 0x00 0x00 0x00 Amplitude scale factor[9:8] N/A 0x00 0x00 N/A N/A [31:24] [23:16] [15:8] [7:0] Rising delta word[31:24] Rising delta word[23:16] Rising delta word[15:8] Rising delta word[7:0] N/A N/A N/A N/A [31:24] [23:16] [15:8] [7:0] Falling delta word[31:24] Falling delta word[23:16] Falling delta word[15:8] Falling delta word[7:0] N/A N/A N/A N/A There are two sets of channel registers and profile registers, one per channel. This is not shown in the Table 29 or Table 30 because the addresses of all channel registers and profile registers are the same for each channel. Therefore, the channel enable bits (CSR[7:6]) determine if the channel registers and/or profile registers of each channel are written to or not. 2 The clear phase accumulator bit (CFR[1]) is set to Logic 1 after a master reset. It self-clears or is set to Logic 0 when an I/O update is asserted. 1 Rev. C | Page 37 of 44 AD9958 Data Sheet Table 30. Profile Register Map 1 Register Name (Address) Channel Word 1 (CW1) (0x0A) Channel Word 2 (CW2) (0x0B) Channel Word 3 (CW3) (0x0C) Channel Word 3 (CW4) (0x0D) Channel Word 5 (CW5) (0x0E) Channel Word 6 (CW6) (0x0F) Channel Word 7 (CW7) (0x10) Channel Word 8 (CW8) (0x11) Channel Word 9 (CW9) (0x12) Channel Word 10 (CW10) (0x13) Channel Word 11 (CW11) (0x14) Channel Word 12 (CW12) (0x15) Channel Word 13 (CW13) (0x16) Channel Word 14 (CW14) (0x17) Channel Word 15 (CW15) (0x18) 1 Bit Range [31:0] [31:0] [31:0] [31:0] [31:0] [31:0] [31:0] [31:0] [31:0] [31:0] [31:0] [31:0] [31:0] [31:0] [31:0] Bit 7 Bit 0 (MSB) Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 (LSB) Frequency tuning word[31:0] or phase word[31:18] or amplitude word[31:22] Frequency tuning word[31:0] or phase word[31:18] or amplitude word[31:22] Frequency tuning word[31:0] or phase word[31:18] or amplitude word[31:22] Frequency tuning word[31:0] or phase word[31:18] or amplitude word[31:22] Frequency tuning word[31:0] or phase word[31:18] or amplitude word[31:22] Frequency tuning word[31:0] or phase word[31:18] or amplitude word[31:22] Frequency tuning word[31:0] or phase word[31:18] or amplitude word[31:22] Frequency tuning word[31:0] or phase word[31:18] or amplitude word[31:22] Frequency tuning word[31:0] or phase word[31:18] or amplitude word[31:22] Frequency tuning word[31:0] or phase word[31:18] or amplitude word[31:22] Frequency tuning word[31:0] or phase word[31:18] or amplitude word[31:22] Frequency tuning word[31:0] or phase word[31:18] or amplitude word[31:22] Frequency tuning word[31:0] or phase word[31:18] or amplitude word[31:22] Frequency tuning word[31:0] or phase word[31:18] or amplitude word[31:22] Frequency tuning word[31:0] or phase word[31:18] or amplitude word[31:22] Default Value N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Each channel word register has a capacity of 32 bits. If phase or amplitude is stored in the channel word registers, it must be first MSB aligned per the bit range. Only the MSB byte is shown for each channel word register. Rev. C | Page 38 of 44 Data Sheet AD9958 DESCRIPTIONS FOR CONTROL REGISTERS Channel Select Register (CSR)—Address 0x00 One byte is assigned to this register. The CSR determines if channels are enabled or disabled by the status of the two channel enable bits. Both channels are enabled by their default state. The CSR also determines which serial mode of operation is selected. In addition, the CSR offers a choice of MSB first or LSB first format. Table 31. Bit Descriptions for CSR Bit 7:6 Mnemonic Channel [1:0] enable 5:4 3 2:1 Open Must be 0 Serial I/O mode select 0 LSB first Description Bits are active immediately after being written. They do not require an I/O update to take effect. There are two sets of channel registers and profile (channel word) registers, one per channel. This is not shown in the channel register map or the profile register map. The addresses of all channel registers and profile registers are the same for each channel. Therefore, the channel enable bits distinguish the channel registers and profile registers values of each channel. For example, 10 = only Channel 1 receives commands from the channel registers and profile registers. 01 = only Channel 0 receives commands from the channel registers and profile registers. 11 = both Channel 0 and Channel 1 receive commands from the channel registers and profile registers. Must be set to 0. 00 = single-bit serial (2-wire mode). 01 = single-bit serial (3-wire mode). 10 = 2-bit serial mode. 11 = 4-bit serial mode. See the Serial I/O Modes of Operation section for more details. 0 = the serial interface accepts serial data in MSB first format (default). 1 = the serial interface accepts serial data in LSB first format. Function Register 1 (FR1)—Address 0x01 Three bytes are assigned to this register. FR1 is used to control the mode of operation of the chip. Table 32. Bit Descriptions for FR1 Bit 23 Mnemonic VCO gain control 22:18 PLL divider ratio 17:16 Charge pump control 15 14:12 Open Profile pin configuration (PPC) 11:10 Ramp-up/ramp-down (RU/RD) 9:8 Modulation level 7 Reference clock input power-down Description 0 = the low range (system clock below 160 MHz) (default). 1 = the high range (system clock above 255 MHz). If the value is 4 or 20 (decimal) or between 4 and 20, the PLL is enabled and the value sets the multiplication factor. If the value is outside of 4 and 20 (decimal), the PLL is disabled. 00 (default) = the charge pump current is 75 µA. 01 = charge pump current is 100 µA. 10 = charge pump current is 125 µA. 11 = charge pump current is 150 µA. The profile pin configuration bits control the configuration of the data and SDIO_x pins for the different modulation modes. See the Modulation Mode section in this document for details. The RU/RD bits control the amplitude ramp-up/ramp-down time of a channel. See the Output Amplitude Control Mode section for more details. The modulation (FSK, PSK, and ASK) level bits control the level (2/4/8/16) of modulation to be performed for a channel. See the Modulation Mode section for more details. 0 = the clock input circuitry is enabled for operation (default). 1 = the clock input circuitry is disabled and is in a low power dissipation state. Rev. C | Page 39 of 44 AD9958 Bit 6 Mnemonic External power-down mode 5 SYNC_CLK disable 4 DAC reference power-down 3:2 1 Open Manual hardware sync 0 Manual software sync Data Sheet Description 0 = the external power-down mode is in fast recovery power-down mode (default). In this mode, when the PWR_DWN_CTL input pin is high, the digital logic and the DAC digital logic are powered down. The DAC bias circuitry, PLL, oscillator, and clock input circuitry are not powered down. 1 = the external power-down mode is in full power-down mode. In this mode, when the PWR_DWN_CTL input pin is high, all functions are powered down. This includes the DAC and PLL, which take a significant amount of time to power up. 0 = the SYNC_CLK pin is active (default). 1 = the SYNC_CLK pin assumes a static Logic 0 state (disabled). In this state, the pin drive logic is shut down. However, the synchronization circuitry remains active internally to maintain normal device operation. 0 = DAC reference is enabled (default). 1 = DAC reference is powered down. See the Synchronizing Multiple AD9958 Devices section for details. 0 = the manual hardware synchronization feature of multiple devices is inactive (default). 1 = the manual hardware synchronization feature of multiple devices is active. 0 = the manual software synchronization feature of multiple devices is inactive (default). 1 = the manual software synchronization feature of multiple devices is active. See the Synchronizing Multiple AD9958 Devices section for details. Function Register 2 (FR2)—Address 0x02 Two bytes are assigned to this register. The FR2 is used to control the various functions, features, and modes of the AD9958. Table 33. Bit Descriptions for FR2 Bit 15 Mnemonic All channels autoclear sweep accumulator 14 All channels clear sweep accumulator All channels autoclear phase accumulator 13 12 11:8 7 6 5 4 3: 2 1:0 All channels clear phase Accumulator Open Auto sync enable Multidevice sync master enable Multidevice sync status Multidevice sync mask Open System clock offset Description 0 = a new delta word is applied to the input, as in normal operation, but not loaded into the accumulator (default). 1 = this bit automatically and synchronously clears (loads 0s into) the sweep accumulator for one cycle upon reception of the I/O_UPDATE sequence indicator on both channels. 0 = the sweep accumulator functions as normal (default). 1 = the sweep accumulator memory elements for both channels are asynchronously cleared. 0 = a new frequency tuning word is applied to the inputs of the phase accumulator, but not loaded into the accumulator (default). 1 = this bit automatically and synchronously clears (loads 0s into) the phase accumulator for one cycle upon receipt of the I/O update sequence indicator on both channels. 0 = the phase accumulator functions as normal (default). 1 = the phase accumulator memory elements for both channels are asynchronously cleared. See the Synchronizing Multiple AD9958 Devices section for more details. See the Synchronizing Multiple AD9958 Devices section for more details. See the Synchronizing Multiple AD9958 Devices section for more details. See the Synchronizing Multiple AD9958 Devices section for more details. See the Synchronizing Multiple AD9958 Devices section for more details. Rev. C | Page 40 of 44 Data Sheet AD9958 DESCRIPTIONS FOR CHANNEL REGISTERS Channel Function Register (CFR)—Address 0x03 Three bytes are assigned to this register. Table 34. Bit Descriptions for CFR Bit 23:22 21:16 15 Mnemonic Amplitude frequency phase (AFP) select Open Linear sweep no-dwell 14 Linear sweep enable 13 Load SRR at I/O_UPDATE 12:11 10 9:8 7 Open Must be 0 DAC full-scale current control Digital power-down 6 DAC power-down 5 Matched pipe delays active 4 Autoclear sweep accumulator 3 Clear sweep accumulator Autoclear phase accumulator 2 1 0 Clear phase accumulator Sine wave output enable Description Controls what type of modulation is to be performed for that channel. See the Modulation Mode section for details. 0 = the linear sweep no-dwell function is inactive (default). 1 = the linear sweep no-dwell function is active. If CFR[15] is active, the linear sweep no-dwell function is activated. See the Linear Sweep Mode section for details. If CFR[14] is clear, this bit is don’t care. 0 = the linear sweep capability is inactive (default). 1 = the linear sweep capability is enabled. When enabled, the delta frequency tuning word is applied to the frequency accumulator at the programmed ramp rate. 0 = the linear sweep ramp rate timer is loaded only upon timeout (timer = 1) and is not loaded because of an I/O_UPDATE input signal (default). 1 = the linear sweep ramp rate timer is loaded upon timeout (timer = 1) or at the time of an I/O_UPDATE input signal. Must be set to 0. 11 = the DAC is at the largest LSB value (default). See Table 5 for other settings. 0 = the digital core is enabled for operation (default). 1 = the digital core is disabled and is in its lowest power dissipation state. 0 = the DAC is enabled for operation (default). 1 = the DAC is disabled and is in its lowest power dissipation state. 0 = matched pipe delay mode is inactive (default). 1 = matched pipe delay mode is active. See the Single-Tone Mode—Matched Pipeline Delay section for details. 0 = the current state of the sweep accumulator is not impacted by receipt of an I/O_UPDATE signal (default). 1 = the sweep accumulator is automatically and synchronously cleared for one cycle upon receipt of an I/O_UPDATE signal. 0 = the sweep accumulator functions as normal (default). 1 = the sweep accumulator memory elements are asynchronously cleared. 0 = the current state of the phase accumulator is not impacted by receipt of an I/O_UPDATE signal (default). 1 = the phase accumulator is automatically and synchronously cleared for one cycle upon receipt of an I/O_UPDATE signal. 0 = the phase accumulator functions as normal (default). 1 = the phase accumulator memory elements are asynchronously cleared. 0 = the angle-to-amplitude conversion logic employs a cosine function (default). 1 = the angle-to-amplitude conversion logic employs a sine function. Rev. C | Page 41 of 44 AD9958 Data Sheet Channel Frequency Tuning Word 0 (CFTW0)—Address 0x04 Four bytes are assigned to this register. Table 35. Description for CFTW0 Bit 31:0 Mnemonic Frequency Tuning Word 0 Description Frequency Tuning Word 0 for each channel. Channel Phase Offset Word 0 (CPOW0)—Address 0x05 Two bytes are assigned to this register. Table 36. Description for CPOW0 Bit 15:14 13:0 Mnemonic Open Phase Offset Word 0 Description Phase Offset Word 0 for each channel. Amplitude Control Register (ACR)—Address 0x06 Three bytes are assigned to this register. Table 37. Description for ACR Bit 23:16 15:14 Mnemonic Amplitude ramp rate Increment/decrement step size Open Description Amplitude ramp rate value. Amplitude increment/decrement step size. 12 Amplitude multiplier enable 11 Ramp-up/ramp-down enable 10 Load ARR at I/O_UPDATE 9:0 Amplitude scale factor 0 = amplitude multiplier is disabled. The clocks to this scaling function (auto RU/RD) are stopped for power saving, and the data from the DDS core is routed around the multipliers (default). 1 = amplitude multiplier is enabled. This bit is valid only when ACR[12] is active high. 0 = when ACR[12] is active, Logic 0 on ACR[11] enables the manual RU/RD operation. See the Output Amplitude Control Mode section for details (default). 1 = if ACR[12] is active, a Logic 1 on ACR[11] enables the auto RU/RD operation. See the Output Amplitude Control Mode section for details. 0 = the amplitude ramp rate timer is loaded only upon timeout (timer = 1) and is not loaded due to an I/O_UPDATE input signal (default). 1 = the amplitude ramp rate timer is loaded upon timeout (timer = 1) or at the time of an I/O_UPDATE input signal. Amplitude scale factor for each channel. 13 Rev. C | Page 42 of 44 Data Sheet AD9958 Linear Sweep Ramp Rate (LSRR)—Address 0x07 Two bytes are assigned to this register. Table 38. Description for LSRR Bit 15:8 7:0 Mnemonic Falling sweep ramp rate (FSRR) Rising sweep ramp rate (RSRR) Description Linear falling sweep ramp rate. Linear rising sweep ramp rate. LSR Rising Delta Word (RDW)—Address 0x08 Four bytes are assigned to this register. Table 39. Description for RDW Bit 31:0 Mnemonic Rising delta word Description 32-bit rising delta-tuning word. LSR Falling Delta Word (FDW)—Address 0x09 Four bytes are assigned to this register. Table 40. Description for FDW Bit 31:0 Mnemonic Falling delta word Description 32-bit falling delta-tuning word. Rev. C | Page 43 of 44 AD9958 Data Sheet OUTLINE DIMENSIONS 0.30 0.23 0.18 0.60 MAX 0.60 MAX 43 1 42 PIN 1 INDICATOR 7.85 7.75 SQ 7.65 0.50 BSC 6.25 6.10 SQ 5.95 EXPOSED PAD 29 TOP VIEW 1.00 0.85 0.80 SEATING PLANE 0.80 MAX 0.65 TYP 12° MAX 0.50 0.40 0.30 14 28 15 BOTTOM VIEW 0.25 MIN 6.50 REF 0.05 MAX 0.02 NOM COPLANARITY 0.20 REF 0.08 SIDE VIEW PIN 1 INDICATOR 56 FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. COMPLIANT TO JEDEC STANDARDS MO-220-VLLD-2 06-07-2012-A 8.10 8.00 SQ 7.90 Figure 50. 56-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 8 mm × 8 mm Body, Very Thin Quad (CP-56-1) Dimensions shown in millimeters ORDERING GUIDE Model 1 AD9958BCPZ AD9958BCPZ-REEL7 AD9958/PCBZ 1 Temperature Range −40°C to +85°C −40°C to +85°C Package Description 56-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 56-Lead Lead Frame Chip Scale Package [LFCSP_VQ] Evaluation Board Z = RoHS Compliant Part. ©2005–2016 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05252-0-11/16(C) Rev. C | Page 44 of 44 Package Option CP-56-1 CP-56-1