ASNT7123A-KMA

ASNT7123A-KMA 16GS/s, 4-bit Flash Analog-to-Digital Converter with HS Outputs 20GHz analog input bandwidth Selectable clocking mode: external high-speed clock or internal PLL with external reference clock Broadband operation in external clocking mode: DC-16GS/s On-chip PLL with a central frequency of 10GHz Selectable on-chip 16Gbps PRBS 215-1 generator for output data scrambling Differential CML input clock buffer and output data and clock buffers Differential linear data input buffer LVDS input reference clock buffer Selectable on-chip digital-to-analog converter for self-testing Single +3.5V power supply Power consumption: 4.62W Custom 100-pin metal-ceramic package vee 75 vee 74 nc 73 nc 72 vcc 71 nc 70 nc 69 vcc 68 nc 67 nc 66 vcc 65 nc 64 nc 63 vcc 62 rstn 61 rstp 60 vcc 59 vee 58 odn 57 odp 56 vcc 55 n/c 54 n/c 53 vcc 52 vee 51             Rev. 1.0.2 ASNT7122 ASNT7123A  Power consum vee 50 vrefcrl 49 vlsbcrl 48 ondac 47 nc 46 onprbs 45 vcc 44 vee 43 vee 42 vcc 41 dp 40 dn 39 vcc 38 vee 37 vee 36 vcc 35 cep 34 cen 33 vcc 32 vee 31 vee 30 vcc 29 crp 28 crn 27 vcc 26 1 vee 2 vee 3 nc 4 nc 5 vcc 6 chop 7 chon 8 vcc 9 nc 10 nc 11 vcc 12 nc 13 nc 14 vcc 15 vee 16 ondata 17 nc 18 nc 19 lol 20 ftr 21 vee 22 ceoff 23 nc 24nc cpcsel 25 vcc 76 vcc 77 nc 78 nc 79 vcc 80 q03p 81 q03n 82 vcc 83 nc 84 nc 85 vcc 86 q02p 87 q02n 88 vcc 89 q01p 90 q01n 91 vcc 92 nc 93 nc 94 vcc 95 q00p 96 q00n 97 vcc 98 nc 99 nc 100 vcc 1 October 2020 DESCRIPTION ondac DAC ondata vrefcrl vlsbcrl dp/dn rstp/n onprbs ftr lol crp/crn cep/cen LIB 15 4-bit TTB Flash 15 Encoder ADC LOB SCR x4 odp/odn OB CMLx4 q00p/q00n q01p/q01n q02p/q02n q03p/q03n OB CML chop/chon PRBS CMU & Divider ceoff Fig. 1. Functional Block Diagram The ASNT7123A-KMA is a 4-bit flash analog to digital converter (ADC) featuring a high sampling rate, and wide analog front-end bandwidth. The ADC system shown in Fig. 1 includes a linear input buffer (LIB) with tree-type architecture, and a CML-type input interface with internal 50Ohm single-ended terminations to vcc. The buffer delivers 15 matching copies of the input analog data signal dp/dn to the 4-bit flash ADC. The ADC creates 15 samples of the input data in thermometer code, which are then converted by a thermometer-to-binary encoder (TTB Encoder) into 4-bit binary words with a data rate f. The ADC thresholds are controlled by signals vrefcrl and vlsbcrl. The encoded data is processed by a scrambler (SCRx4) where it is mixed with a 215-1 PRBS signal provided by an internal high-speed PRBS generator (PRBS). The scrambled data is delivered to a 4-bit differential CML output interface (OB CMLx4, pins q00p/q00n, q01p/q01n, q02p/q02n, q03p/q03n). The PRBS generator can be preset to a certain initial state by the differential external signal rstp/rstn, or completely disabled by control signal onprbs. When disabled, the generator allows data to pass unchanged through the scrambler. It is also possible to disable the data by using control signal ondata, and pass the PRBS signal to the outputs. An optional digital-to-analog converter (DAC) with an output signal odp/odn can be used to control the ADC’s operation. It is enabled by control signal ondac. All operations are synchronized by the internal clock multiplication unit (CMU) based on a PLL (phaselocked loop) with an integrated divider, and an external loop filter connected to pin ftr. The block can operate in two different modes, and is controlled by signal ceoff: they can either be clock multiplication (PLL is on, a reference clock is applied to pins crp/crn), or clock division (PLL is off, an external highspeed clock is applied to pins cep/cen). In both modes, the divider generates internal clock signals divided by 2, 4, 8, and 16. The generated divided clocks are sent to different internal blocks. A PLL lock control output lol is also provided. The part operates from a single +3.5V power supply. All external control signals are compatible with the 2.5V CMOS interface. Rev. 1.0.2 2 October 2020 Linear Input Buffer (LIB) The system includes a linear input buffer (LIB) with a tree-type architecture that delivers 15 matching copies of the wide-band input differential analog data signal dp/dn to the 4-bit flash section. Symmetry is closely followed in both schematic, and layout to ensure minimal aperture jitter. Clock Multiplication Unit (CMU) & Divider The PLL-based CMU with its external loop filter connected to pin ftr as shown in Fig. 2 can operate in two different modes. In the first “clock multiplication” mode (ceoff=”1”, default), the CMU multiplies the external reference clock crp/crn with a speed of f/16 by means of a PLL with a central frequency of f and a wide tuning range of the internal VCO (voltage-controlled oscillator). The generated clock is processed by the divider in order to generate internal clock signals divided by 2, 4, 8, and 16. 100Ohm To pin 20 (ftr) 1nF vee Fig. 2. Recommended External Loop Filter Schematic In the second “clock division” mode (ceoff=”0”), the PLL is disabled and the internal clocks are generated from the external high-speed clock inputs cep/cen. HS External Clock Input Buffer The high-speed external clock input buffer can accept high-speed clock signals at its differential CML input port cep/cen. It can also accept a single-ended signal with AC or DC termination. In case of AC termination, the unused pin should be also AC terminated with a 50Ohm load. In case of DC termination, a threshold voltage must be applied to the unused pin. Differential input signaling must be used for input clock frequencies above 14GHz. The buffer can handle a wide range of input signal amplitudes. The buffer utilizes on-chip single-ended termination of 50Ohm to vcc for each input line. LS Reference Clock Input Buffer The low-speed reference clock input buffer is a proprietary LVDS buffer with internal 100Ohm differential termination between its inputs crp/crn. The buffer exceeds the requirements of standards IEEE Std. 1596.3-1996 and ANSI/TIA/EIA-644-1995. It is designed to accept differential signals with amplitudes above 100mV peak-to-peak (p-p), a wide range of DC common mode voltages, and AC common mode noise with a frequency up to 5MHz and voltage levels ranging from 0 to 2.4V. 4-bit Flash Analog to Digital Converter (ADC) with Encoder This block samples the incoming analog data with the clock signal provided by the CMU in order to generate a 4-bit output digital signal (Bit 0 – Bit 3) with MSB corresponding to Bit 3. The threshold voltages (Vth 1 - Vth 15) of the ADC can be adjusted through analog signals vrefcrl and vlsbcrl as shown in Table 1. As can be seen, vrefcrl shifts the DC levels of all the threshold voltages simultaneously by the same amount in relation to vcc and vlsbcrl alters the voltage range of the least significant bit (LSB) while also shifting the DC levels. Table 1. Simulated ADC Threshold Control States vrefcrl. mV vlsbcrl. mV Vth 15, mV min (vcc – 960) min (vcc – 700) vcc-35 min (vcc – 960) max (vcc – 260) vcc-345 max (vcc) min (vcc – 700) vcc-355 Rev. 1.0.2 3 Vth 8, mV vcc-54 vcc-751 vcc-361 Vth 1, mV Vth (X+1) – Vth X, mV vcc-73 2.7 vcc-1157 58 vcc-366 0.8 October 2020 max (vcc) max (vcc – 260) vcc-665 vcc-1058 vcc-1450 56 If no external voltages are applied to vrefcrl and vlsbcrl, it is recommended to have both pins ACterminated by 50Ohm resistors to vee through DC blocks! The corresponding default states are vrefcrl=vlsbcrl=vcc-0.48V. HS PRBS Generator (PRBS) The on-chip selectable high-speed generator provides a full 32-kbit long pseudo-random binary sequence (PRBS) signal according to the polynomial (x15 + x14 + 1), where xD represents a delay of D clock cycles. This is implemented as a linear feedback shift register (LFSR) in which the outputs of the fifteenth and fourteenth flip-flops are combined together by an XOR function and provided as an input to the first flipflop of the register. The block is activated by the external 2.5V CMOS signal onprbs (onprbs=”0” – default state – PRBS generator off, onprbs=”1” – PRBS generator on). The same signal sets the PRBS output to logic “0” state that is required for the transparency of the following scrambler block SCRx4. The LSFR-based PRBS generator produces 32,767 binary states, excluding the “all zeros” state that is illegal for the XOR-based configuration. To eliminate this state that locks the LFSR and prevents PRBS generation, an asynchronous external CML reset signal (rstp/rstn) should be applied to the circuit. When the reset is asserted, LSFR is set to the all-“1” state that is enough for the activation of PRBS generation. When the preset is released, the block delivers four copies of the same signal to the scrambler. Scrambler (SCRx4) The scrambler SCHx4 consists of four symmetrical XOR gates that mix four signals delivered by the encoder with the generated PRBS signal. To ensure reliable operation of the block, all signals are retimed by D-type flip-flops before and after the scrambling. The scrambler can be configured to pass either scrambled data (ondata=”1”, default), or PRBS signal only (ondata=”0”). Digital to Analog Converter (DAC) A DAC block is included to perform a quick test of the ADC’s functionality. When activated by external control signal (ondac=”1”), it converts the digital data into a step-wise copy of the input signal that is sent to the output odp/odn through a linear differential output buffer LOB. The circuit is not consuming any power when disabled (ondac=”0”, default). CML Data Output Buffers (OB CMLx4) The data output buffers (OB CMLx4) receive four high-speed data signals from the scrambler and convert them into differential CML output signals q00p/q00n, q01p/q01n, q02p/q02n, and q03p/q03n. Each buffer utilizes internal single-ended 50Ohm loads to vcc and requires single-ended 50Ohm external termination. The termination resistors can be connected from each output directly to vcc, or through DC blocks to vee. The output drivers of the buffers are slightly linearized to deliver optimal eye shape. CML Clock Output Buffer (OB CML) The high-speed clock output buffer (OB CML) is a replica of one data output buffer. TERMINAL FUNCTIONS Pin # 1 2 Rev. 1.0.2 Pin name vee vee Pin type supply voltage supply voltage Pin function negative power supply negative power supply 4 Termination or connection GND GND October 2020 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 n/c n/c vcc chop chon vcc n/c n/c vcc n/c n/c vcc vee ondata n/c n/c lol ftr vee ceoff n/c n/c vcc vcc crn crp vcc vee vee vcc cen cep vcc vee vee vcc Pin Pin # name 39 dn 40 dp 41 vcc 42 vee 43 vee 44 vcc 45 onprbs 46 n/c 47 ondac Rev. 1.0.2 supply voltage CML output CML output supply voltage supply voltage supply voltage supply voltage CMOS input CMOS output supply voltage CMOS input supply voltage supply voltage LVDS input supply voltage supply voltage supply voltage supply voltage CML input CML input supply voltage supply voltage supply voltage supply voltage Pin type Analog input Analog input supply voltage supply voltage supply voltage supply voltage CMOS input CMOS input not used not used positive power supply HS output clock, direct 50Ohm to vcc HS output clock, inverted 50Ohm to vcc positive power supply not used not used positive power supply not used not used positive power supply negative power supply GND Data to output on/off 1MOhm to 2.5V not used not used PLL no-lock indicator External filter connection negative power supply GND Clock multiplication/division mode 1MOhm to 2.5V not used not used positive power supply positive power supply LS reference input clock, direct 100Ohm between pins LS reference input clock, inverted positive power supply negative power supply GND negative power supply GND positive power supply HS input clock, direct 50Ohm to vcc HS input clock, inverted 50Ohm to vcc positive power supply negative power supply GND negative power supply GND positive power supply Pin function HS input data, direct HS input data, inverted positive power supply negative power supply negative power supply positive power supply PRBS enable/disable not used DAC enable/disable 5 Termination or connection 50Ohm to vcc 50Ohm to vcc GND GND 1MOhm to vee 1MOhm to vee October 2020 ADC threshold voltages controls vlsbcrl Analog voltage 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 vrefcrl Analog voltage 12KOhm to vcc vee supply voltage negative power supply GND vee supply voltage negative power supply GND vcc supply voltage positive power supply n/c not used n/c not used vcc supply voltage positive power supply odp Analog output DAC output signal, direct 50Ohm to vcc odn Analog output DAC output signal, inverted 50Ohm to vcc vee supply voltage negative power supply GND vcc supply voltage positive power supply rstp CML input HS PRBS reset signal, direct 50Ohm to vcc rstn CML input HS PRBS reset signal, inverted 50Ohm to vcc vcc supply voltage positive power supply n/c not used n/c not used vcc supply voltage positive power supply n/c not used n/c not used vcc supply voltage positive power supply n/c not used n/c not used vcc supply voltage positive power supply n/c not used n/c not used vee supply voltage negative power supply GND vee supply voltage negative power supply GND vcc supply voltage positive power supply n/c not used n/c not used vcc supply voltage positive power supply Pin Pin Pin Pin # name type function 80 q03p CML output Output data Bit 3, direct 81 q03n CML output Output data Bit 3, inverted 82 vcc supply voltage positive power supply 83 n/c not used 84 n/c not used 85 vcc supply voltage positive power supply 86 q02p CML output Output data Bit 2, direct 87 q02n CML output Output data Bit 2, inverted 88 vcc supply voltage positive power supply 89 q01p CML output Output data Bit 1, direct 90 q01n CML output Output data Bit 1, inverted 91 vcc supply voltage positive power supply Rev. 1.0.2 12KOhm to vcc 48 6 Termination or connection 50Ohm to vcc 50Ohm to vcc 50Ohm to vcc 50Ohm to vcc 50Ohm to vcc 50Ohm to vcc October 2020 92 93 94 95 96 97 98 99 100 n/c n/c vcc q00p q00n vcc n/c n/c vcc not used not used supply voltage positive power supply CML output Output data Bit 0, direct 50Ohm to vcc CML output Output data Bit 0, inverted 50Ohm to vcc supply voltage positive power supply not used not used supply voltage positive power supply ABSOLUTE MAXIMUM RATINGS Caution: Exceeding the absolute maximum ratings presented in Table 2 may cause damage to this product and/or lead to reduced reliability. Functional performance is specified over the recommended operating conditions for power supply and temperature only. AC and DC device characteristics at or beyond the absolute maximum ratings are not assumed or implied. All min and max voltage limits are referenced to ground (vee). Table 2. Absolute Maximum Ratings Parameter Supply Voltage (vcc) Power Consumption RF Input Voltage Swing (SE) Case Temperature Storage Temperature Operational Humidity Storage Humidity Min -40 10 10 Max 4.0 5.5 1.4 +100 +100 98 98 Units V W V ºC ºC % % ELECTRICAL CHARACTERISTICS PARAMETER vcc vee Ivcc Power consumption Junction temperature Bandwidth CM Level Linearity range Frequency Swing CM Voltage Level Rev. 1.0.2 MIN TYP MAX UNIT General Parameters 3. 4 3.5 3.6 V 0.0 V 1320 mA 4.62 W -25 50 125 °C Analog Input Data (dp/dn) 0.0 20 GHz vcc-0.8 vcc V ±110 mV HS Input Clock (cep/cen) DC 16 GHz 0.2 1.0 V vcc-0.8 vcc V 7 COMMENTS ±3% External ground With PRBS and DAC enabled With PRBS enabled Must match for both inputs Differential or SE, p-p Differential or SE, p-p Must match for both inputs October 2020 Duty Cycle 40 50 60 % LS Reference Input Clock (crp/crn) Frequency 560 688 MHz 1/16 of VCO frequency CM Level 0.2 vcc V Voltage Swing 100 800 mV Differential Duty Cycle 40 50 60 % HS Output Clock and Data (chop/chon, q00p/q00n to q03p/q03n) Data Rate DC 16 Gbps For data signals Frequency DC 16 GHz For clock signals Logic “1” level V vcc Logic “0” level vcc-0.6 V Rise/Fall Times TBD ps 20%-80% DAC Output (odp/odn) Voltage Swing 250 350 mV Single-ended. p-p CM Level vcc-(voltage swing)/2 V Analog Control Signals (vrefcrl, vlsbcrl) Voltage range V see Table 1 CML Control Signals (rstp/rstn) Pulse width 83 ps 1 period of HS clock Swing 0.2 0.8 V Differential or SE, p-p CM Voltage Level vcc-0.8 vcc V Must match for both inputs CMOS Control Signals (ceoff, ondac, onprbs, ondata) Logic “1” level vee+2.3 vee+2.5 V Logic “0” level vee+0.2 V Frequency 3.5 GHz ELECTRICAL SPECIFICATIONS Parameter ENOB (5GS/s) ENOB (8GS/s) ENOB (10GS/s) ENOB (12GS/s) SFDR (5GS/s) SFDR (10GS/s) SINAD (5GS/s) SINAD (10GS/s) DNL INL Conditions fin = 3.9GHz fin = 8.0GHz fin = 10.0GHz fin = 12.0GHz fin = 3.9GHz fin = 7.8GHz fin = 3.9GHz fin = 7.8GHz Min -0.2 -0.2 Typical 3.39 3.35 3.30 3.26 30.13 28.78 -22.15 -21.19 Max 0.2 0.2 Units bits bits bits bits dBFS dBFS dB dB lsbs lsbs Fig. 3 presents ENOB measured at the sampling rates of 9GSps and 14GSps. The differential input signal is applied through a coupler or from the outputs of the ADSANTEC’s analog signal splitter ASNT6114. Rev. 1.0.2 8 October 2020 Fig. 3. ENOB at 9GSps and 14GSps PACKAGE INFORMATION The chip die is housed in a custom 100-pin CQFP package shown in Fig. 4. Rev. 1.0.2 9 October 2020 Fig. 4. CQFP 100-Pin Package Drawing (All Dimensions in mm) The package provides a center heat slug located on its back side to be used for heat dissipation. ADSANTEC recommends for this section to be soldered to the vcc plain, which is power for a positive supply. The part’s identification label is ASNT7123A-KMA. The first 8 characters of the name before the dash identify the bare die including general circuit family, fabrication technology, specific circuit type, and part Rev. 1.0.2 10 October 2020 version while the 3 characters after the dash represent the package’s manufacturer, type, and pin out count. This device complies with Commission Delegated Directive (EU) 2015/863 of 4 June 2015 amending Annex II to Directive 2011/65/EU of the European Parliament and of the Council as regards the list of restricted substances (Text with EEA relevance) on the restriction of the use of certain hazardous substances in electrical and electronics equipment (RoHS Directive) in accordance with the definitions set forth in the directives for all ten substances. REVISION HISTORY Revision 1.0.1 Rev. 1.0.2 Date 03-2020 Initial release Changes 11 October 2020