GS9035C

G S9035C *(1/,1; ™,, GS9035C Serial Digital Reclocker DATA SHEET FEATURES • adjustment-free operation • auto-rate selection for 4 SMPTE data rates: 143, 177, 270, 360Mb/s • data rate indication output • serial data output mute when PLL is not locked • operation independent of SAV/EAV sync signals • low jitter, low power • single external VCO resistor for operation with four input data rates • large input jitter tolerance: typically 0.50 UI beyond loop bandwidth at 270Mb/s • power savings mode (output serial clock disable) • system friendly: serial clock remains active when data outputs muted • robust lock detect APPLICATIONS The GS9035C is used for Clock and Data recovery, and Jitter elimination for all high speed serial digital interface applications involving SMPTE 259M and other data standards. DESCRIPTION The GS9035C is a high performance clock and data recovery IC designed for serial digital data. The GS9035C receives either single-ended or differential PECL data and outputs differential PECL clock and retimed data signals. The GS9035C can operate in either auto or manual rate selection mode. In auto mode the GS9035C is ideal for multi-rate serial data protocols such as SMPTE 259M. In this mode the GS9035C automatically detects and locks onto the incoming data signal. For single rate data systems, the GS9035C can be configured to operate in manual mode. In both modes, the GS9035C requires only one external resistor to set the VCO centre frequency and provides adjustment-free operation. The GS9035C has dedicated pins to indicate LOCK and data rate. In addition, an internal muting function forces the serial data outputs to a static state when input data is not present or when the PLL is not locked. The serial clock outputs can also be disabled resulting in a 10% power savings. The GS9035C is packaged in a 28 pin PLCC and operates from a single +5 or -5 volt power supply. ORDERING INFORMATION PART NUMBER PACKAGE TEMPERATURE GS9035C GS9035CCPJ GS9035CCTJ 28 pin PLCC 28 pin PLCC Tape 0°C to 70°C 0°C to 70°C COSC CARRIER DETECT PHASELOCK HARMONIC LOGIC LOCK SDO FREQUENCY ACQUISITION 2 SDO PHASE DETECTOR CLK_EN SCO SCO DIVISION 2 BIT COUNTER SMPTE AUTO/MAN DDI/DDI CHARGE PUMP VCO DECODER SSO SS1 LF+ LFS LF- CBG RVCO BLOCK DIAGRAM Revision Date: June 2003 GENNUM CORPORATION P.O. Box 489, Stn. A, Burlington, Ontario, Canada L7R 3Y3 Tel. +1 (905) 632-2996 Fax. +1 (905) 632-5946 E-mail: info@gennum.com www.gennum.com Document No. 20582 - 3 ABSOLUTE MAXIMUM RATINGS PARAMETER VALUE Supply Voltage (VS) Input Voltage Range (any input) Operating Temperature Range Storage Temperature Range Lead Temperature (soldering, 10 sec) 5.5V VCC + 0.5 to VEE - 0.5V 0°C ≤ TA ≤ 70°C -65°C ≤ TS ≤ 150°C 260°C GS9035C DC ELECTRICAL CHARACTERISTICS VCC = 5.0V, VEE = 0V, TA = 0°C to 70°C unless otherwise stated, RLF = 1.8K, CLF1 = 15nF, CLF2 = 3.3pF. PARAMETER CONDITION MIN TYPICAL 1 MAX UNITS NOTES TEST LEVEL Supply Voltage Supply Current CLK_EN = 0 CLK_EN = 1 DDI/DDI Common Mode Input Voltage Range DDI/DDI Differential Input Drive AUTO/MAN, SMPTE High Low CLK_EN Input Voltage High Low LOCK Output Low Voltage SS[1:0] Output Voltage 4.75 VEE + (VDIFF/2) 200 2.0 2.5 500µA 5.00 90 105 0.4 to 4.6 800 0.25 4.8 5.25 110 120 VCC - (VDIFF/2) 2000 0.8 0.8 0.4 - V mA mA V mV V 2 3 3 3 3 3 3 V 3 ΙOH = 4.4 V V 3 1 1 HIGH, ΙOH = -180µA, Auto Mode LOW, ΙOL = 600µA, Auto Mode - 0.3 0.4 SS[1:0] Input Voltage HIGH, Manual Mode LOW, ManualMode 2 - 26 0.8 55 V 3 CLK_EN Source Current Low, VIL = 0V µA 1 NOTES 1. TYPICAL - measured on EB-RD35A board. 2. VDIFF is the differential input signal swing. 3. LOCK is an open collector output and requires an external pull-up resistor. 4. Pins SS[1:0] are outputs in AUTO mode and inputs in MANUAL mode. TEST LEVELS 1. Production test at room temperature and nominal supply voltage with guardbands for supply and temperature ranges. 2. Production test at room temperature and nominal supply voltage with guardbands for supply and temperature ranges using correlated test. 3. Production test at room temperature and nominal supply voltage. 4. 5. 6. 7. 8. QA sample test. Calculated result based on Level 1,2, or 3. Not tested. Guaranteed by design simulations. Not tested. Based on characterization of nominal parts. Not tested. Based on existing design/characterization data of similar product. 9. Indirect Test. 10.Production test at room temperature. 2 of 14 GENNUM CORPORATION 20582 - 3 AC ELECTRICAL CHARACTERISTICS VCC = 5.0V, VEE = 0V, TA = 0°C to 70°C unless otherwise stated, RLF = 1.8K, CLF1 = 15nF, CLF2 = 3.3pF 1 PARAMETER CONDITION MIN TYPICAL MAX UNITS NOTES TEST LEVEL Serial Data Rate Intrinsic Jitter Psuedorandom (223 - 1) Intrinsic Jitter (Pathological SDI checkfield) Input Jitter Tolerance SDI 270Mb/s 143 - 185 360 See Figure 4 Mb/s ps p-p 2 3 4 GS9035C 270Mb/s 360Mb/s 270Mb/s 360Mb/s 0.40 0.38 0.5 -200 462 308 0.50 1 1 4 10 1 0 800 300 See Figure 5 ps p-p 2 3 2 200 1000 400 UI UI µs ms ms ms µs ps mV p-p ps 3 3 1,4 9 1 8 Lock Time Synchronous Switch tSWITCH < 0.5µs, 270Mb/s 0.5µs < tSWITCH < 10ms tSWITCH > 10ms Lock Time Asynchronous Switch SDO MUTE Time SDO to SCO Synchronization SDO, SCO Output Signal Swing SDO, SCO Rise and Fall Times Loop Bandwidth = 4.5MHz at 360Mb/s 1,5 6 8 8 8 1 8 75Ω DC load 20% - 80% 600 200 NOTES 1. TYPICAL - measured on EB-RD35A board, TA = 25°C. 2. Characterized 6 sigma rms. 3. IJT measured with sinusoidal modulation beyond Loop Bandwidth (at 6.5MHz). 4. Synchronous switching refers to switching the input data from one source to another source which is at the same data rate (ie: line 10 switching for component NTSC). 5. Asynchronous switching refers to switching the input data from one source to another source which is at a different data rate. 6. SDO MUTE Time refers to the response of the SDO output from valid re-clocked input data to mute mode when the input signal is removed. TEST LEVEL 1. Production test at room temperature and nominal supply voltage with guardbands for supply and temperature ranges. 2. Production test at room temperature and nominal supply voltage with guardbands for supply and temperature ranges using correlated test. 3. Production test at room temperature and nominal supply voltage. 4. QA sample test. 5. Calculated result based on Level 1,2, or 3. 6. Not tested. Guaranteed by design simulations. 7. Not tested. Based on characterization of nominal parts. 8. Not tested. Based on existing design/characterization data of similar product. 9. Indirect test 10.Production test at room temperature. TEKTRONIX GIGABERT 1400 CLK DATA DI DI GENNUM TEST BOARD SDO TEKTRONIX CSA803 CH-1 TRIG PATTERN 223-1 3 of 14 GENNUM CORPORATION 20582 - 3 Fig. 1 Jitter Measurement Test Setup PIN CONNECTIONS CLK_EN SMPTE COSC LOCK VCC3 VEE VEE GS9035C 4 DDI DDI VEE VEE VCC1 AUTO/MAN VEE 5 6 7 8 9 10 11 12 LF+ 3 2 1 28 27 26 25 24 23 SDO SDO SCO SCO SSO SS1 RSV1 GS9035C TOP VIEW 22 21 20 19 13 LFS 14 LF- 15 RVCO_RTN 16 RVCO 17 CBG 18 VCC2 PIN DESCRIPTIONS NUMBER SYMBOL TYPE DESCRIPTION 1,7,8,11,27 2 3 4 5, 6 9 10 12 13 14 15 16 17 18 19 20 - 21 22, 23 24, 25 26 28 VEE COSC LOCK SMPTE DDI/DDI VCC1 AUTO/MAN LF+ LFS LFRVCO_RTN RVCO CBG VCC2 RSV1 SS[1:0] SCO/SCO SDO/SDO VCC3 CLK_EN I I O I I I I I I I I I I I I I/O O O I I Most negative power supply connection. Timing control capacitor for internal system clock. Lock indication. When HIGH, the GS9035C is locked. LOCK is an open collector output and requires an external 10k pullup resistor. SMPTE/Other rate select. Digital data input (Differential ECL/PECL). Most positive power supply connection. Auto or Manual mode select. TTL/CMOS compatible input. Loop filter component connection. Loop filter component connection. Loop filter component connection. RVCO return. Frequency setting resistor. Internal bandgap voltage filter capacitor. Most positive power supply connection. Reserved Input. Always connect to GND Data rate indication (Auto mode) or data rate select (Manual mode). TTL/CMOS compatible I/O. In auto mode these pins can be left unconnected. Serial clock output. SCO/SCO are differential current mode outputs and require external 75Ω pullup resistors. Serial data output. SDO/SDO are differential current mode outputs and require external 75Ω pullup resistors. Most positive power supply connection. Clock enable. When HIGH, the serial clock outputs are enabled. 4 of 14 GENNUM CORPORATION 20582 - 3 TYPICAL PERFORMANCE CURVES (VS = 5V, TA = 25°C unless otherwise shown.) 1000 800 Max JITTER (ps p-p) GS9035C 600 Typical 400 Min 200 Typical Range, Characterized 0 100 200 300 400 SDI DATA RATE (Mb/s) TA = 0 to 70˚C, VCC = 4.75 to 5.25V for the typical range Fig. 2 Intrinsic Jitter (2 -1 Pattern) 143Mb/s 23 Fig. 5 Intrinsic Jitter - Pathological SDI Checkfield 0.6 0.5 0.4 IJT (UI) 0.3 0.2 0.1 0 100 200 300 400 DATA RATE (Mb/s) TA = 0 to 70˚C, VCC = 4.75 to 5.25V Fig. 3 Intrinsic Jitter (2 -1 Pattern) 270Mb/s 23 Fig. 6 Typical Input Jitter Tolerance (Characterized) 1000 0.600 143Mb/s 0.550 177Mb/s 270Mb/s 800 0.500 0.450 JITTER (ps) 600 360Mb/s IJT (UI) Max Typical Min Typical Range, Characterized 400 0.400 0.350 0.300 0.250 0.200 200 0 100 200 300 400 0 10 20 30 40 50 60 70 SDI DATA RATE (Mb/s) TA=0 to 70˚C, VCC=4.75 to 5.25V for the typical range TEMPERATURE (C˚) Fig. 7 Typical IJT vs. Temperature (VCC=5.0V) (Characterized) Fig. 4 Intrinsic Jitter - Pseudorandom (223 -1) 5 of 14 GENNUM CORPORATION 20582 - 3 DETAILED DESCRIPTION The GS9035C receives either a single-ended or differential PECL serial data stream at the DDI and DDI inputs. It locks an internal clock to the incoming data and outputs the differential PECL retimed data signal and recovered clock on outputs SDO/SDO and SCO/SCO respectively. The timing between the input, output, and clock signals is shown below. signal data rate. A single low impedance external resistor, RVCO, sets the VCO center frequency (see Figure 9). The low impedance RVCO minimizes thermal noise and reduces the PLL's sensitivity to PCB noise. For a given RVCO value, the VCO can oscillate at one of two frequencies. When SMPTE = SS0 = logic 1, the VCO center frequency corresponds to the ƒL curve. For all other SMPTE/SS0 combinations, the VCO center frequency corresponds to the ƒH curve (ƒH is approximately 1.5 x ƒL). 800 700 GS9035C DDI VCO FREQUENCY (MHz) SDO 600 500 400 300 200 100 0 0 200 400 600 800 1000 1200 1400 1600 1800 SCO 50% ƒH Fig. 8 Input/Output Clock Signal Timing The GS9035C reclocker contains four main functional blocks: the Phase Locked Loop, Auto/Manual Data Rate Select, Frequency Acquisition, and Logic Circuit. 1. PHASE LOCKED LOOP (PLL) ƒL SMPTE=1 SSO=1 RVCO (Ω) The Phase Locked Loop locks the internal PLL clock to the incoming data rate. A simplified block diagram of the PLL is shown below. The main components are the VCO, the phase detector, the charge pump, and the loop filter. 2 PHASE DETECTOR INTERNAL PLL CLOCK DIVISION Fig. 10 VCO Frequency vs. RVCO The recommended RVCO value for auto rate SMPTE 259M applications is 365Ω. The VCO and an internal divider generate the PLL clock. Divider moduli of 1, 2, and 4 allow the PLL to lock to data rates from 143Mb/s to 360Mb/s. The divider modulus is set by the AUTO/MAN, SMPTE, and SS[1:0] pin (see Auto/Manual Data Rate Select section for further details). When the input data stream is removed for an excessive period of time (see AC electrical characteristics table), the VCO frequency can drift from the previously locked frequency up to the maximum shown in Table 1. TABLE 1: Frequency Drift Range (when PLL loses lock) DDI/DDI CHARGE PUMP LF+ LFS LFLOOP FILTER VCO RVCO LOSES LOCK FROM MIN (%) MAX(%) RLF CLF1 CLF2 143Mb/s lock 177Mb/s lock 270Mb/s lock -21 -12 -13 -13 21 26 28 24 Fig. 9 Simplified Diagram of the PLL 360 Mb/s lock 1.1 VCO The VCO is a differential low phase noise, factory trimmed design that provides increased immunity to PCB noise and precise control of the VCO center frequency. The VCO operates between 143 and 360Mb/s and has a pull range of -13 +25% about the center frequency depending on the 6 of 14 GENNUM CORPORATION 20582 - 3 1.2 Phase Detector The phase detector compares the phase of the PLL clock with the phase of the incoming data signal and generates error correcting timing pulses. The phase detector design provides a linear transfer function between the input phase and output timing pulses maximizing the input jitter tolerance of the PLL. 1.3 Charge Pump The charge pump takes the phase detector output timing pulses and creates a charge packet that is proportional to the system phase error. A unique differential charge pump design ensures that the output phase does not drift when data transitions are sparse. This makes the GS9035C ideal for SMPTE 259M applications where pathological signals have data transition densities of 0.05. 1.4 Loop Filter The VCO frequency starts at point A and sweeps up attempting to lock. If lock is not established during the up sweep, the VCO is then swept down. The system is designed such that the probability of locking within one cycle period is greater than 0.999. If the system does not lock within one cycle period, it will attempt to lock in the subsequent cycle. In manual mode, the divider modulus is fixed for all cycles. In auto mode, each subsequent cycle is based on a different divider moduli as determined by the internal 2-bit counter. The average sweep time, tswp, is determined by the loop filter component, CLF1, and the charge pump current, ΙCP: GS9035C tswp = 4 CLF1 3 Ι LF1 [seconds] The loop filter integrates the charge pump packets and produces a VCO control voltage. The loop filter is comprised of three external components which are connected to pins LF+, LFS, and LF-. The loop filter design is fully differential giving the GS9035C increased immunity to PCB board noise. The loop filter components are critical in determining the loop bandwidth and damping of the PLL. Choosing these component values is discussed in detail in the PLL Design Guidelines section. Recommended values for SMPTE 259M applications are shown in the Typical Application Circuit diagram. 2. FREQUENCY ACQUISITION The nominal sweep time is approximately 121µs when CLF1 = 15nF and ΙCP = 165µA (RVCO = 365Ω). An internal system clock determines tsys (see section 7, Logic Circuit). 3. LOGIC CIRCUIT The GS9035C is controlled by a finite state logic circuit which is clocked by an asynchronous system clock. That is, the system clock is completely independent of the incoming data rate. The system clock runs at low frequencies, relative to the incoming data rate, and thus reduces interference to the PLL. The period of the system clock is set by the COSC capacitor and is tsys = 9.6 x 10 x COSC 4 [seconds] The core PLL is able to lock if the incoming data rate and the PLL clock frequency are within the PLL capture range (which is slightly larger than the loop bandwidth). To assist the PLL to lock to data rates outside of the capture range, the GS9035C uses a frequency acquisition circuit. The frequency acquisition circuit sweeps the VCO control voltage such that the VCO frequency changes from -10% to +10% of the center frequency. Figure 11 shows a typical sweep waveform. tswp tsys The recommended value for tsys is 450µs (COSC = 4.7nF). 4. AUTO/MANUAL DATA RATE SELECT The GS9035C can operate in either auto or manual data rate select mode. The mode of operation is selected by a single input pin (AUTO/MAN). 4.1 Auto Mode (AUTO/MAN = 1) VLF In auto mode, the GS9035C uses a 2-bit counter to automatically cycle through four (SMPTE=1) or two (SMPTE=0) different divider moduli as it attempts to acquire lock. In this mode, the SS[1:0] pins are outputs and indicate the current value of the divider moduli according to Table 2. Note that for SMPTE = 0 and divider moduli of 2 and 4, the PLL can correctly lock for two values of SS[1:0]. A Tcycle Tcycle = tswp + tsys Fig. 11 Typical Sweep Form 7 of 14 GENNUM CORPORATION 20582 - 3 TABLE 2: Data Rate Indication in Auto Mode AUTO/MAN = 1 (Auto Mode) ƒH, ƒL = VCO center frequency as per Figure 10 SMPTE SS[1:0] DIVIDER MODULI PLL CLOCK 1 1 1 1 0 0 0 0 00 01 10 11 00 01 10 11 4 2 2 1 4 4 2 2 ƒH/4 ƒL/2 ƒH/2 ƒL ƒH/4 ƒH/4 ƒH/2 ƒH/2 The GS9035C assumes that it is NOT locked to a harmonic if the pattern ‘101’ or ‘010’ (in the reclocked data stream) occurs at least once every tsys/3 seconds. Using the recommended component values, this corresponds to approximately 150µs. (In a harmonically locked system, all bit cells are double clocked and the above patterns become ‘110011’ and ‘001100’, respectively.) GS9035C 5.1 Lock Time The lock time of the GS9035C depends on whether the input data is switching synchronously or asynchronously. Synchronous switching refers to the case where the input data is changed from one source to another source which is at the same data rate (but different phase). Asynchronous switching refers to the case where the input data to the GS9035C is changed from one source to another source which is at a different data rate. When input data to the GS9035C is removed, the GS9035C latches the current state of the counter (divider modulus). Therefore, when data is reapplied, the GS9035C begins the lock procedure at the previous locked data rate. As a result, in synchronous switching applications, the GS9035C locks very quickly. The nominal lock time depends on the switching time and is summarized in the table below: TABLE 4: Lock Time Relative to Switching Time 4.2 Manual Mode (AUTO/MAN = 0) In manual mode, the GS9035C divider moduli is fixed. In this mode, the SS[1:0] pins are inputs and set the divider moduli according to Table 3. TABLE 3: Data Rate Select in Manual Mode AUTO/MAN = 0 (Manual Mode) ƒH, ƒL = VCO center frequency as per Figure 10 SMPTE SS[1:0] DIVIDER MODULI PLL CLOCK SWITCHING TIME LOCK TIME 1 1 1 1 0 0 0 0 00 01 10 11 00 01 10 11 4 2 2 1 4 4 2 2 ƒH/4 ƒL/2 ƒH/2 ƒL ƒH/4 ƒH/4 ƒH/2 ƒH/2 10ms 10µs 2tsys 2Tcycle + 2tsys 5. LOCKING The GS9035C indicates lock when three conditions are satisfied: 1. Input data is detected. 2. The incoming data signal and the PLL clock are phase locked. 3. The system is not locked to a harmonic. The GS9035C defines the presence of input data when at least one data transition occurs every 1µs. In asynchronous switching applications (including power up) the lock time is determined by the frequency acquisition circuit as described in section 2, Frequency Acquisition. In manual mode, the frequency acquisition circuit may have to sweep over an entire cycle (depending on initial conditions) to acquire lock resulting in a maximum lock time of 2Tcycle + 2tsys. In auto tune mode, the maximum lock time is 6Tcycle + 2tsys since the frequency acquisition circuit may have to cycle through 5 possible counter states (depending on initial conditions) to acquire lock. The nominal value of Tcycle for the GS9035C operating in a typical SMPTE 259M application is approximately 1.3ms. The GS9035C has a dedicated LOCK output (pin 3) indicating when the device is locked. It should be noted that in synchronous switching applications where the switching time is less than 0.5µs, the LOCK output will NOT be de-asserted and the data outputs will NOT be muted. 8 of 14 GENNUM CORPORATION 20582 - 3 5.2 DVB-ASI Design Note: For DVB-ASI applications having significant instances of few bit transitions or when only K28.5 idle bits are transmitted, the wide-band PLL in the GS9035C may lock at 243MHz being the first 27MHz sideband below 270MHz. When normal bit density signals are transmitted, the PLL will correctly lock onto the proper 270MHz carrier. 6. OUTPUT DATA MUTING PHASE DETECTOR Øi + KPD - ΙCP VCO 2πKf Ns Øo LOOP FILTER RLF CLF1 CLF2 GS9035C The GS9035C internally mutes the SDO and SDO outputs when the device is not locked. When muted, SDO/SDO are latched providing a logic state to the subsequent circuit and avoiding a condition where noise could be amplified and appear as data. The output data muting timing is shown in Figure 12. DDI NO DATA TRANSITIONS Fig. 13 PLL Model 9.1 Transfer Function The transfer function of the PLL is defined as Øo/Øi and can be approximated as sC LF1 R LF + 1 Øo 1 ------ = --------------------------------------------------------------- --------------------------------------------------------2 L L Øi C s  LF1 R LF – ---------  + 1 s C LF2 L + s -------- + 1 R R LF LF LOCK Equation 1 SDO VALID DATA OUTPUTS MUTED VALID DATA where N L = ------------------DICP K ƒ N is the divider modulus D is the data density (=0.5 for NRZ data) ΙCP is the charge pump current in Amps Kƒ is the VCO gain in Hz/V This response has 1 zero (wZ) and three poles (wP1, wBW, wP2) where 1 w Z = ---------------------C LF1 R LF 1 w P1 = -------------------------------------L C LF1 RLF – --------R LF R LF w BW = --------L 1 w P2 = ---------------------C LF2 R LF The bode plot for this transfer function is plotted in Figure 14. Fig. 12 Output Data Muting Timing 7. CLOCK ENABLE When CLK_EN is high, the GS9035C SCO/SCO outputs are enabled. When CLK_EN is low, the SCO/SCO outputs are set to a high Z state and float to VCC. Disabling the clock outputs results in a power savings of 10%. It is recommended that the CLK_EN input be hard wired to the desired state. For applications which do not require the clock output, connect CLK_EN to Ground and connect the SCO/SCO outputs to VCC. 8. STRESSFUL DATA PATTERNS All PLL's are susceptible to stressful data patterns which can introduce bit errors in the data stream. PLL's are most sensitive to patterns which have long run lengths of zeros or ones (low data transition densities for a long period of time). The GS9035C is designed to operate with low data transition densities such as the SMPTE 259M pathological signal (data transition density = 0.05). 9. PLL DESIGN GUIDELINES The performance of the GS9035C is primarily determined by the PLL. Thus, it is important that the system designer is familiar with the basic PLL design equations. A model of the GS9035C PLL is shown below. The main components are the phase detector, the VCO, and the external loop filter components. 9 of 14 GENNUM CORPORATION 20582 - 3 The second is the zero-pole combination: 0 AMPLITUDE (dB) s------ + 1 wZ sC LF1 R LF + 1 ---------------------------------------------------------- = ------------------s L --------- + 1 s  C LF1 R LF – ----------  + 1  w P1 RLF  This causes lift in the transfer function given by w P1 120 LOG --------- = 20 LOG -------------------wZ wZ 1 – ----------w BW WZ WP1 FREQUENCY WBW WP2 GS9035C To keep peaking to less than 0.05dB, wZ < 0.0057 wBW 9.3 Selection of Loop Filter Components Fig. 14 Bode Plot for PLL Transfer Function The 3dB bandwidth of the transfer function is approximately w 3dB w BW w BW = --------------------------------------------------------------------- ≈ ----------2 0.78 w BW ( w BW ⁄ w P2 ) 1 – 2 ----------- + --------------------------------w P2 w BW ----------1–2 w P2 Based on the above analysis, select the loop filter components for a given PLL bandwidth, ƒ3dB, as follows: 1. Calculate where ΙCP is the charge pump current and is a function of the RVCO resistor and is obtained from Figure 15. Kƒ = 90MHz/V for VCO frequencies corresponding to the ƒL curve. Kƒ = 140MHz/V for VCO frequencies corresponding to the ƒH curve. N is the divider modulus. (ƒL, ƒH and N can be obtained from Table 2 or Table 3). 9.2 Transfer Function Peaking There are two causes of peaking in the PLL transfer function given by Equation 1. The first is the quadratic L s C LF2 L + s --------- + 1 R LF 2 which has 1 w O = -------------------C LF2 L C LF2 Q = R LF -----------L and 2. Choose RLF = 2(3.14) ƒ3dB (0.78)L 3. Choose CLF1 = 174 L / (RLF)2 4. Choose CLF2 = L/4(RLF) 2 This response is critically damped for Q = 0.5. Thus, to avoid peaking: R LF or L 1 ---------------------- --------- > 4 R LF CLF2 R LF Therefore, wP2 > 4 wBW However, it is desirable to keep wP2 as low as possible to reduce the high frequency content on the loop filter. C LF2 1 ------------ < --2 L L= ΙCPKƒ 2N 10 of 14 GENNUM CORPORATION 20582 - 3 400 CHARGE PUMP CURRENT (µA) 350 300 250 200 150 100 50 0 0 200 400 600 800 1000 1200 1400 1600 1800 RVCO (Ω) SPICE NETLIST * GS9035C PLL Model .PARAM ICP = 165E-6 KF= 90E+6 .PARAM N = 1 D = 0.5 .PARAM PI = 3.14 .IC V(Phio) = 0 .ac dec 30 1k 10meg RLF 1 LF 1000 CLF1 1 0 15n CLF2 0 LF 15p E_LAPLACE1 Phio 0 LAPLACE {V(LF)} {(2*PI*KF)/(N*s)} G1 0 LF VALUE{D * ICP/(2*pi)*V(Phii, Phio)} V1 2 0 DC 0V AC 1V R2 0 1 1g .END 10. I/O DESCRIPTION 10.1 High Speed Inputs (DDI/DDI) GS9035C Fig. 15 Charge Pump Current vs. RVCO 9.4 Spice Simulations More detailed analysis of the GS9035C PLL can be done using SPICE. A SPICE model of the PLL is shown below: PHII IN+ INRLF 1 CLF1 R2 DDI/DDI are high impedance inputs which accept differential or single-ended input drive. Two conditions must be observed when interfacing to these inputs: 1. Input signal amplitudes are between 200 and 2000mV G1 LF PHIO E1 2πKƒ Ns 2. The common mode input voltage range is as specified in the DC Characteristics table. Commonly used interface Figures 17 and 18. examples are shown in V1 CLF2 NOTE: PHII, PHIO, LF and 1 are node names in the SPICE netlist. Fig. 16 SPICE Model of PLL The model consists of a voltage controlled current source (G1), the loop filter components (RLF, CLF1, and CLF2), a voltage controlled voltage source (E1), and a voltage source (V1). R2 is necessary to create a DC path to ground for Node 1. V1 is used to generate the input phase waveform. G1 compares the input and output phase waveforms and generates the charge pump current, ΙCP. The loop filter components integrate the charge pump current to establish the loop filter voltage. E1 creates the output phase waveform (PHIO) by multiplying the loop filter voltage by the value of the Laplace transform (2pKƒ/Ns). The netlist for the model is given below. The .PARAM statements are used to set values for ΙCP, Kƒ, N, and D. ΙCP is determined by the RVCO resistor and is obtained from Figure 15. Figure 18 illustrates the simplest interface to the GS9035C. In this example, the driving device generates the PECL level signals (800mV amplitudes) having a common mode input range between 0.4 and 4.6V. This scheme is recommended when the trace lengths are less than 1in. The value of the resistors and the DC connection (VCC or Ground), depends on the output driver circuitry of the previous device. VCC or GND DDI GS9035C DDI VCC or GND Fig. 17 Simple Interface to the GS9035C 11 of 14 GENNUM CORPORATION 20582 - 3 When trace lengths become greater than 1in, controlled impedance traces should be used. The recommended interface for differential signals is shown in Figure 18. In this case, a parallel resistor (RLOAD) is placed near the GS9035C inputs to terminate the controlled impedance trace. The value of RLOAD should be twice the value of the characteristic impedance of the trace. Both traces should be in a symmetric arrangement and same physical transmission line dimensions since common-mode signals or common-mode noise is not terminated. In addition, series resistors, RSOURCE, can be placed near the driving chip to serve as source terminations. They should be equal to the value of the trace impedance. Assuming 800mV output swings at the driver, RLOAD =100Ω, RSOURCE =50Ω and ZO = 50Ω. 10.2 High Speed Outputs (SDO/SDO and SCO/SCO) SDO/SDO and SCO/SCO are current mode outputs that require external pullup resistors (see Figure 20). To calculate the output sink current use the following relationship: Output Sink Current = Output Signal Swing / Pullup Resistor GS9035C A diode can be placed between Vcc and the pullup resis tors to reduce the common mode voltage by approximately 0.7 volts. When the output traces are longer than 1in, controlled impedance traces should be used. The pullup resistors should be placed at the end of the output traces as they terminate the trace in its characteristic impedance (75Ω). VCC RSOURCE RSOURCE ZO DDI RLOAD DDI ZO GS9035C GS9035C SDO SDO SCO SCO 75Ω 75Ω Fig. 18 Recommended Interface for Differential Signals Figure 19 shows the recommended interface when the GS9035C is driven single-endedly. In this case, the input must be AC-coupled and a matching resistor (ZO) must be used. 75Ω 75Ω VCC Fig. 20 High Speed Outputs with External Pullups DDI ZO DDI GS9035C Fig. 19 Recommended Interface for Single-Ended Driver 12 of 14 GENNUM CORPORATION 20582 - 3 TYPICAL APPLICATION CIRCUIT The figure below shows the GS9035C connected in a typical auto rate select SMPTE 259M application. Table 5 summarizes the relevant system parameters. VCC VCC 10k 4.7n 4 SMPTE 3 LOCK 2 COSC 1 VEE VCC VCC VCC VCC GS9035C 28 CLK_EN 27 VEE 26 VCC3 4 x 75 SDO 25 From GS9024 5 DDI 6 DDI SDO 24 To GS90201 7 VEE VEE VCC1 AUTO/MAN RVCO_RTN GS9035C TOP VIEW SCO 23 8 SCO 22 VCC VCC 9 SSO 21 10 SS1 20 } To LED Driver (optional) RVCO All resistors in ohms, all capacitors in farads, unless otherwise shown. Power supply decoupling capacitors are not shown. See application note "EB9035A" for details on PCB artwork. 12 RLF 1800 13 CLF1 15n 14 15 RVCO 16 365 (1%) 17 0.1µ 18 VCC2 0.1µ VCC CBG 11 LF+ LFS VEE RSV1 19 LF- NOTE 1. The 75Ω pullup resistors on SDO/SDO and SCO/SCO are not required when interfacing the GS9035C to the GS9020 since the GS9020 has internal 75W resistors. CLF2 3.3p TABLE 5: System Parameters RVCO = 365Ω, ƒH = 540MHz, ƒL = 360MHz SMPTE SS[1:0] DATA RATE (Mb/s) LOOP BANDWIDTH 1 1 1 1 00 01 10 11 143 177 270 360 1.2MHz 1.9MHz 3.0MHz 4.5MHz 13 of 14 GENNUM CORPORATION 20582 - 3 PACKAGE DIMENSIONS 12.573 MAX 12.319 MIN 1.219 x 45 1.067 11.582 MAX 11.430 MIN SEATING PLANE MIN 0.508 GS9035C 1.270 12.573 MAX 12.319 MIN 11.582 MAX 11.430 MIN 10.922 MAX 9.906 MIN 3.048 MAX 2.286 MIN 4.572 MAX 4.115 MIN All dimensions in millimetres. 28 pin PLCC (QM) CAUTION ELECTROSTATIC SENSITIVE DEVICES DO NOT OPEN PACKAGES OR HANDLE EXCEPT AT A STATIC-FREE WORKSTATION REVISION NOTES: Change TEST LEVELS from 3 to 1 for LOCK, SS[2:0] and CLK_EN parameters in DC ELectrical Characteristic Table. Change TEST LEVEL 10 to 3 for Supply Voltage in DC Electrical Characteristic Table. Change TEST LEVEL 3 to 9 for INPUT JITTER TOLERANCE in AC Electrical Characteristic Table. For latest product information, visit www.gennum.com GENNUM JAPAN CORPORATION Shinjuku Green Tower Building 27F, 6-14-1, Nishi Shinjuku, Shinjuku-ku, Tokyo, 160-0023 Japan Tel. +81 (03) 3349-5501, Fax. +81 (03) 3349-5505 GENNUM UK LIMITED 25 Long Garden Walk, Farnham, Surrey, England GU9 7HX Tel. +44 (0)1252 747 000 Fax +44 (0)1252 726 523 DOCUMENT IDENTIFICATION DATA SHEET The product is in production. Gennum reserves the right to make changes at any time to improve reliability, function or design, in order to provide the best product possible. GENNUM CORPORATION MAILING ADDRESS: P.O. Box 489, Stn. A, Burlington, Ontario, Canada L7R 3Y3 Tel. +1 (905) 632-2996 Fax. +1 (905) 632-5946 SHIPPING ADDRESS: 970 Fraser Drive, Burlington, Ontario, Canada L7L 5P5 Gennum Corporation assumes no responsibility for the use of any circuits described herein and makes no representations that they are free from patent infringement. © Copyright July 1999 Gennum Corporation. All rights reserved. Printed in Canada. 14 of 14 20582 - 3