High Voltage, Fractional-N/ Integer-N PLL Synthesizer ADF4150HV FEATURES GENERAL DESCRIPTION Fractional-N synthesizer and integer-N synthesizer High voltage charge pump: VP = 6 V to 30 V Tuning range: 1.0 V to 29 V (or ±1 V from VP supply rails) RF bandwidth to 3.0 GHz Programmable divide-by-1/-2/-4/-8/-16 outputs Synthesizer power supply: 3.0 V to 3.6 V Programmable dual-modulus prescaler of 4/5 or 8/9 Programmable output power level Programmable charge pump currents RF output mute function 3-wire serial interface Analog and digital lock detect The ADF4150HV is a 3.0 GHz, fractional-N or integer-N frequency synthesizer with an integrated high voltage charge pump. The synthesizer can be used to drive external wideband VCOs directly, eliminating the need for operational amplifiers to achieve higher tuning voltages. This simplifies design and reduces cost while improving phase noise, in contrast to active filter topologies, which tend to degrade phase noise compared to passive filter topologies. APPLICATIONS A simple 3-wire interface controls all on-chip registers. The charge pump operates from a power supply ranging from 6 V to 30 V, whereas the rest of the device operates from 3.0 V to 3.6 V. The ADF4150HV can be powered down when not in use. The VCO frequency can be divided by 1, 2, 4, 8, or 16 to allow the user to generate RF output frequencies as low as 31.25 MHz. For applications that require isolation, the RF output stage can be muted. The mute function is both pin- and software-controllable. Wireless infrastructure Microwave point-to-point/point-to-multipoint radios VSAT radios Test equipment Private land mobile radios FUNCTIONAL BLOCK DIAGRAM SDVDD REFIN CLK DATA LE ×2 DOUBLER AVDD 10-BIT R COUNTER DVDD VP RSET MULTIPLEXER ÷2 DIVIDER LOCK DETECT DATA REGISTER LD HIGH VOLTAGE CHARGE PUMP FUNCTION LATCH PHASE COMPARATOR CURRENT SETTING INTEGER VALUE MUXOUT FRACTION VALUE DIVIDE-BY-1/ -2/-4/-8/-16 MODULUS VALUE CPOUT BOOST MODE OUTPUT STAGE RFOUT+ RFOUT– PDBRF THIRD-ORDER FRACTIONAL INTERPOLATOR RF INPUT MULTIPLEXER RFIN+ RFIN– ADF4150HV CE GND CPGND SDGND 09058-001 N COUNTER Figure 1. Rev. 0 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 www.analog.com Fax: 781.461.3113 ©2011 Analog Devices, Inc. All rights reserved. ADF4150HV TABLE OF CONTENTS Features .............................................................................................. 1 Register 1 ..................................................................................... 17 Applications ....................................................................................... 1 Register 2 ..................................................................................... 17 General Description ......................................................................... 1 Register 3 ..................................................................................... 19 Functional Block Diagram .............................................................. 1 Register 4 ..................................................................................... 19 Revision History ............................................................................... 2 Register 5 ..................................................................................... 19 Specifications..................................................................................... 3 Register Initialization Sequence ............................................... 19 Timing Characteristics ................................................................ 5 RF Synthesizer—A Worked Example ...................................... 20 Absolute Maximum Ratings............................................................ 6 Reference Doubler and Reference Divider ............................. 20 Transistor Count ........................................................................... 6 12-Bit Programmable Modulus ................................................ 20 Thermal Resistance ...................................................................... 6 Spurious Optimization and Boost Mode ................................ 21 ESD Caution .................................................................................. 6 Spur Mechanisms ....................................................................... 21 Pin Configuration and Function Descriptions ............................. 7 Spur Consistency and Fractional Spur Optimization ........... 21 Typical Performance Characteristics ............................................. 9 Phase Resync ............................................................................... 22 Circuit Description ......................................................................... 11 Applications Information .............................................................. 23 Reference Input Section ............................................................. 11 Ultrawideband PLL .................................................................... 23 RF N Divider ............................................................................... 11 Microwave PLL ........................................................................... 23 Phase Frequency Detector (PFD) and High Voltage Charge Pump .............................................................................. 11 Generating the High Voltage Supply ....................................... 24 MUXOUT and Lock Detect ...................................................... 12 PCB Design Guidelines for a Chip Scale Package ................. 25 Input Shift Registers ................................................................... 12 Output Matching ........................................................................ 26 Program Modes .......................................................................... 12 Outline Dimensions ....................................................................... 27 Output Stage ................................................................................ 12 Ordering Guide .......................................................................... 27 Interfacing to the ADuC702x and the ADSP-BF527 ............. 25 Register Maps .................................................................................. 13 Register 0 ..................................................................................... 17 REVISION HISTORY 8/11—Revision 0: Initial Version Rev. 0 | Page 2 of 28 ADF4150HV SPECIFICATIONS AVDD = DVDD = SDVDD = 3.3 V ± 10%; VP = 6.0 V to 30 V; GND = 0 V; TA = TMIN to TMAX, unless otherwise noted. Operating temperature range is −40°C to +85°C. Table 1. Parameter REFIN CHARACTERISTICS Input Frequency Max Unit Test Conditions/Comments 10 10 300 30 MHz MHz Input Sensitivity Input Capacitance Input Current RF INPUT CHARACTERISTICS 0.7 AVDD 5.0 ±60 V p-p pF μA For f < 10 MHz, ensure slew rate > 21 V/μs Reference doubler enabled (DB25 bit in Register 2 is set to 1) Biased at AVDD/2; ac coupling ensures AVDD/2 bias RF Input Frequency (RFIN) Prescaler Output Frequency PHASE DETECTOR Phase Detector Frequency 0.5 HIGH VOLTAGE CHARGE PUMP ICP Sink/Source High Value Low Value RSET Range High Value vs. RSET Min Typ 3.0 750 GHz MHz 26 20 26 MHz MHz MHz Low noise mode Low spur mode Integer-N mode μA μA kΩ μA μA % % % % nA RSET = 5.1 kΩ RSET = 5.1 kΩ 384 48 3.3 196 10 594 Sink and Source Current Matching Absolute ICP Accuracy ICP vs. VCP ICP vs. Temperature ICP Leakage LOGIC INPUTS Input High Voltage, VINH Input Low Voltage, VINL Input Current, IINH/IINL Input Capacitance, CIN LOGIC OUTPUTS Output High Voltage, VOH Output High Current, IOH Output Low Voltage, VOL POWER SUPPLIES AVDD DVDD, SDVDD VP IP DIDD + AIDD1 Current per Output Divider IRFOUT2 Low Power Sleep Mode 6 3 2.5 2.5 2.5 2.0 0.6 ±1 15.0 V V μA pF 500 0.4 V μA V DVDD − 0.4 3.0 3.6 AVDD 6.0 30 1 50 6 to 24 20 1 For lower RFIN frequencies, ensure slew rate > 400 V/μs −10 dBm ≤ RF input power ≤ +5 dBm 2.5 60 32 Rev. 0 | Page 3 of 28 V V V mA mA mA mA μA RSET = 10 kΩ RSET = 3.3 kΩ 1.0 V ≤ VCP ≤ (VP − 1.0 V); VP = 6 V to 30 V 1.0 V ≤ VCP ≤ (VP − 1.0 V) VCP = VP/2 VCP = VP/2 CMOS output selected IOL = 500 μA Set the VP supply at least 1 V above the maximum desired tuning voltage VP = 30 V Each output divide-by-2 consumes 6 mA typ RF output stage is programmable ADF4150HV Parameter RF OUTPUT CHARACTERISTICS Output Frequency Using RF Output Dividers Harmonic Content (Second) Harmonic Content (Third) Minimum RF Output Power 2 Maximum RF Output Power2 Output Power Variation vs. Supply Output Power Variation vs. Temperature Level of Signal with RF Mute Enabled NOISE CHARACTERISTICS Normalized In-Band Phase Noise Floor (PNSYNTH) 3 Normalized 1/f Noise (PN1_f) 4 RF Output Divider Noise Floor Spurious Signals Due to PFD Frequency Min Typ Max Unit Test Conditions/Comments MHz 500 MHz VCO input and divide-by-16 selected −19 −20 −13 −10 −4 5 ±1 dBc dBc dBc dBc dBm dBm dB ±1 −37 dB dBm Fundamental VCO output Divided VCO output Fundamental VCO output Divided VCO output Programmable in 3 dB steps Programmable in 3 dB steps Pull-up supply on Pin 18 and Pin 19 varied from 3.0 V to 3.6 V From −40°C to +85°C PDBRF pin brought low; RF = 2 GHz −213 dBc/Hz Low noise mode −203 −113 −108 −155 −70 −85 dBc/Hz dBc/Hz dBc/Hz dBc/Hz dBc dBc Low spur mode Low noise mode Low spur mode Measured at 10 MHz offset At RFOUT+/RFOUT− pins At VCO output 31.25 1 TA = 25°C; AVDD = DVDD = 3.3 V; prescaler = 8/9; fREFIN = 100 MHz; fPFD = 25 MHz; fRF = 1.75 GHz. Using 50 Ω resistors to AVDD, into a 50 Ω load. 3 This figure can be used to calculate phase noise for any application. To calculate in-band phase noise performance as seen at the VCO output, use the following formula: PNSYNTH = PNTOT − 10 log(fPFD) − 20 log N. 4 The PLL phase noise is composed of flicker (1/f) noise plus the normalized PLL noise floor. The flicker noise is specified at a 10 kHz offset and normalized to 1 GHz. The formula for calculating the 1/f noise contribution at an RF frequency (fRF) and at a frequency offset (f) is given by PN = PN1_f + 10 log(10 kHz/f) + 20 log(fRF/1 GHz). Both the normalized phase noise floor and flicker noise are modeled in ADIsimPLL. 2 Rev. 0 | Page 4 of 28 ADF4150HV TIMING CHARACTERISTICS AVDD = DVDD = SDVDD = 3.3 V ± 10%; VP = 6.0 V to 30 V; GND = 0 V; TA = TMIN to TMAX, unless otherwise noted. Operating temperature range is −40°C to +85°C. Table 2. Parameter t1 t2 t3 t4 t5 t6 t7 Limit 20 10 10 25 25 10 20 Unit ns min ns min ns min ns min ns min ns min ns min Description LE setup time DATA to CLK setup time DATA to CLK hold time CLK high duration CLK low duration CLK to LE setup time LE pulse width Timing Diagram t4 t5 CLK t2 DATA DB31 (MSB) t3 DB30 DB2 (CONTROL BIT C3) DB1 (CONTROL BIT C2) DB0 (LSB) (CONTROL BIT C1) t7 LE t1 09058-002 t6 LE Figure 2. Timing Diagram Rev. 0 | Page 5 of 28 ADF4150HV ABSOLUTE MAXIMUM RATINGS TA = 25°C, unless otherwise noted. TRANSISTOR COUNT Table 3. The transistor count for the ADF4150HV is 23,380 (CMOS) and 809 (bipolar). Parameter AVDD to GND1 AVDD to DVDD VP to GND1 Digital I/O Voltage to GND1 Analog I/O Voltage to GND1 REFIN to GND1 Operating Temperature Range Storage Temperature Range Maximum Junction Temperature Reflow Soldering Peak Temperature Time at Peak Temperature 1 Rating −0.3 V to +3.9 V −0.3 V to +0.3 V −0.3 V to +33 V −0.3 V to AVDD + 0.3 V −0.3 V to DVDD + 0.3 V −0.3 V to AVDD + 0.3 V −40°C to +85°C −65°C to +125°C 150°C THERMAL RESISTANCE Thermal impedance (θJA) is specified for a device with the exposed pad soldered to GND. Table 4. Thermal Resistance Package Type 32-Lead LFCSP (CP-32-11) ESD CAUTION 260°C 40 sec GND = CPGND = SDGND = 0 V. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Rev. 0 | Page 6 of 28 θJA 27.3 Unit °C/W ADF4150HV 32 31 30 29 28 27 26 25 GND RSET GND SDGND SDVDD MUXOUT LD REFIN PIN CONFIGURATION AND FUNCTION DESCRIPTIONS 1 2 3 4 5 6 7 8 ADF4150HV TOP VIEW (Not to Scale) 24 23 22 21 20 19 18 17 GND GND DVDD PDBRF AVDD RFOUT + RFOUT – GND NOTES 1. THE LFCSP HAS AN EXPOSED PAD THAT MUST BE CONNECTED TO GND. 09058-003 CPOUT CPGND AVDD GND AVDD RFIN+ RFIN– GND 9 10 11 12 13 14 15 16 GND CLK DATA LE CE VP GND GND Figure 3. Pin Configuration Table 5. Pin Function Descriptions Pin No. Mnemonic 1, 7, 8, 12, 16, 17, GND 23, 24, 30, 32 2 CLK 3 DATA 4 LE 5 CE 6 VP 9 CPOUT 10 11, 13, 20 CPGND AVDD 14 15 RFIN+ RFIN− 18 RFOUT− 19 RFOUT+ 21 22 PDBRF DVDD 25 REFIN 26 LD Description Ground. All ground pins should be tied together. Serial Clock Input. Data is clocked into the 32-bit shift register on the CLK rising edge. This input is a high impedance CMOS input. Serial Data Input. The serial data is loaded MSB first with the three LSBs as the control bits. This input is a high impedance CMOS input. Load Enable. When LE goes high, the data stored in the 32-bit shift register is loaded into the register that is selected by the three control bits. This input is a high impedance CMOS input. Chip Enable. A logic low on this pin powers down the device and puts the charge pump into three-state mode. A logic high on this pin powers up the device. High Voltage Charge Pump Power Supply. Place decoupling capacitors to the ground plane as close to this pin as possible. The decoupling capacitors should have the appropriate voltage rating (a value of 10 μF is recommended). Care should be taken to ensure that VP does not exceed the absolute maximum ratings on power-up (see Table 3). A 10 Ω series resistor can help to significantly reduce voltage overshoot with minimal IR drop. High Voltage Charge Pump Output. When enabled, this output provides ±ICP to the external passive loop filter. The output of the loop filter is connected to the voltage tuning port of the external VCO. High Voltage Charge Pump Ground. All ground pins should be tied together. Analog Power Supply. This pin ranges from 3.0 V to 3.6 V. Place decoupling capacitors to the ground plane as close to this pin as possible. AVDD must have the same value as DVDD. Positive RF Input. The output of the VCO or external prescaler should be ac-coupled to this pin. Complementary RF Input. If a single-ended input is required, this pin can be tied to ground via a 100 pF capacitor. Divided-Down Output of RFIN−. This pin can be left unconnected if the divider functionality is not required. Divided-Down Output of RFIN+. This pin can be left unconnected if the divider functionality is not required. RF Power-Down. A logic low on this pin mutes the RF outputs. This function is also software controllable. Digital Power Supply. Place decoupling capacitors to the ground plane as close to this pin as possible. DVDD must have the same value as AVDD. Reference Input. This CMOS input has a nominal threshold of AVDD/2 and a dc equivalent input resistance of 100 kΩ. This input can be driven from a crystal oscillator, TCXO, or other reference. Lock Detect Output. A logic high output on this pin indicates PLL lock. A logic low output indicates loss of PLL lock. Rev. 0 | Page 7 of 28 ADF4150HV Pin No. 27 Mnemonic MUXOUT 28 SDVDD 29 31 SDGND RSET EP Exposed Pad Description Multiplexer Output. The multiplexer output allows the lock detect, the N divider value, or the R counter value to be accessed externally. Digital Σ-Δ Modulator Power Supply. Place decoupling capacitors to the ground plane as close to this pin as possible. SDVDD must have the same value as AVDD. Digital Σ-Δ Modulator Ground. All ground pins should be tied together. Connecting a resistor between this pin and GND sets the charge pump output current. Place the resistor as close to this pin as possible. The nominal voltage bias at the RSET pin is 0.55 V. The relationship between ICP and RSET is as follows: ICP = 1.96/RSET where: RSET = 5.1 kΩ. ICP = 384 μA. Exposed Pad. The LFCSP has an exposed pad that must be connected to GND. Rev. 0 | Page 8 of 28 ADF4150HV ICP MISMATCH (%) ICP = 400µA SOURCE ICP = 350µA SOURCE ICP = 300µA SOURCE ICP = 250µA SOURCE ICP = 200µA SOURCE ICP = 150µA SOURCE ICP = 100µA SOURCE ICP = 50µA SOURCE ICP = 50µA SINK ICP = 100µA SINK ICP = 150µA SINK ICP = 200µA SINK ICP = 250µA SINK ICP = 300µA SINK ICP = 350µA SINK ICP = 400µA SINK 2 4 6 8 10 12 14 16 18 20 22 24 26 28 VCP (V) 0 6 10 12 200kHz 400kHz –50 SPUR LEVEL (dBc) –60 14 16 18 20 22 24 26 28 600kHz 800kHz BEAT NOTE SPUR BEAT NOTE SPUR –70 –80 –90 –100 –110 –120 1k 10k 100k 1M 10M 100M –130 1500 1505 1510 1515 1520 1525 FREQUENCY (MHz) Figure 8. Fractional Spur Levels vs. Frequency, Low Spur Mode; Measured at VCO Output, PFD = 25 MHz, MOD = 125 Figure 5. Active Filter Phase Noise, ADF4150HV vs. ADF4156; Active Filter Implemented Using OP27 Op Amp; PFD = 20 MHz, Loop Bandwidth = 10 kHz, ICP = 300 μA, Carrier Frequency = 1.7 GHz, VP = 28 V –40 2.0 1.9 8 –40 ADF4150HV RMS NOISE = 0.28° ADF4156 RMS NOISE = 0.36° 09058-005 200kHz 400kHz –50 BOOST MODE ON 1.8 600kHz 800kHz –60 SPUR LEVEL (dBc) 1.7 BOOST MODE OFF 1.6 1.5 1.4 1.3 –70 –80 –90 –100 –110 1.1 –120 1.0 0 50 100 150 TIME (µs) 200 250 300 09058-006 1.2 Figure 6. PLL Lock Time with Boost Mode On and Off; Locking over Octave Range Jump (1 GHz to 2 GHz) for PFD = 20 MHz, Loop Bandwidth = 100 kHz, ICP = 300 μA, VP = 28 V, VDD = 3.3 V, REFIN = 100 MHz Rev. 0 | Page 9 of 28 –130 1500 1505 1510 1515 1520 1525 FREQUENCY (MHz) Figure 9. Fractional Spur Levels vs. Frequency, Low Noise Mode; Measured at VCO Output, PFD = 25 MHz, MOD = 125 09058-009 PHASE NOISE (dBc/Hz) 4 Figure 7. Charge Pump Output Mismatch vs. VP, ICP = 200 μA FREQUENCY (Hz) FREQUENCY (GHz) 2 VCP (V) Figure 4. Charge Pump Output Characteristics, VP = 28 V, ICP Varied from 50 μA to 400 μA, RSET = 5.1 kΩ –80 –85 –90 –95 –100 –105 –110 –115 –120 –125 –130 –135 –140 –145 –150 –155 –160 –165 –170 100 VP = 6V MISMATCH (%) VP = 9V MISMATCH (%) VP = 12V MISMATCH (%) VP = 15V MISMATCH (%) VP = 18V MISMATCH (%) VP = 21V MISMATCH (%) VP = 24V MISMATCH (%) VP = 28V MISMATCH (%) 09058-008 0 16 14 12 10 8 6 4 2 0 –2 –4 –6 –8 –10 –12 –14 –16 09058-007 600 550 500 450 400 350 300 250 200 150 100 50 0 –50 –100 –150 –200 –250 –300 –350 –400 –450 –500 09058-004 ICP (µA) TYPICAL PERFORMANCE CHARACTERISTICS ADF4150HV –40 25MHz 50MHz –50 –80 75MHz 100MHz –85 PHASE NOISE (dBc/Hz) –70 –80 –90 –100 –95 –100 LOW NOISE MODE –105 –110 1200 1400 1600 1800 2000 FREQUENCY (MHz) Figure 10. PFD and Reference Spur Levels vs. Frequency at VCO Output, REFIN = 100 MHz, PFD = 25 MHz –40 25MHz 50MHz –50 –110 1000 09058-110 –120 1000 LOW SPUR MODE –90 1050 1100 1150 1200 1250 1300 FREQUENCY (MHz) 09058-112 SPUR LEVEL (dBc) –60 Figure 12. In-Band Phase Noise Measured at 3 kHz Offset for Low Noise Mode and Low Spur Mode, PFD = 25 MHz, PLL Loop Bandwidth = 40 kHz 4 75MHz 100MHz 2 +5dBm 0 OUTPUT POWER (dBm) SPUR LEVEL (dBc) –60 –70 –80 –90 –100 +2dBm –2 –4 –1dBm –6 –4dBm –8 –10 –12 –110 1400 1600 FREQUENCY (MHz) 1800 2000 Figure 11. PFD and Reference Spur Levels vs. Frequency at VCO Output with ADL5541 Buffer Placed Between VCO Output and RF Input, REFIN = 100 MHz, PFD = 25 MHz Rev. 0 | Page 10 of 28 –16 0 500 1000 1500 2000 2500 FREQUENCY (MHz) Figure 13. Single-Ended RF Output Power Level vs. Frequency and Power Setting, RF Output Pins Pulled Up to 3.3 V via 27 nH||50 Ω 09058-113 1200 09058-111 –120 1000 –14 ADF4150HV CIRCUIT DESCRIPTION The PFD frequency (fPFD) equation is REFERENCE INPUT SECTION The reference input stage is shown in Figure 14. The SW1 and SW2 switches are normally closed. The SW3 switch is normally open. When power-down is initiated, SW3 is closed, and SW1 and SW2 are opened. In this way, no loading of the REFIN pin occurs during power-down. POWER-DOWN CONTROL NC 100kΩ TO R COUNTER 09058-010 SW3 NO R Counter Figure 14. Reference Input Stage RF N DIVIDER The RF N divider allows a division ratio in the PLL feedback path. The division ratio is determined by the INT, FRAC, and MOD values, which build up this divider (see Figure 15). RF N DIVIDER FROM VCO OUTPUT/ OUTPUT DIVIDERS where: REFIN is the reference input frequency. D is the REFIN doubler bit. R is the preset divide ratio of the binary 10-bit programmable reference counter (1 to 1023). T is the REFIN divide-by-2 bit (0 or 1). If FRAC = 0 and the DB8 (LDF) bit in Register 2 is set to 1, the synthesizer operates in integer-N mode. The DB8 bit in Register 2 should be set to 1 for integer-N digital lock detect. BUFFER SW1 N = INT + FRAC/MOD TO PFD N COUNTER THIRD-ORDER FRACTIONAL INTERPOLATOR The 10-bit R counter allows the input reference frequency (REFIN) to be divided down to produce the reference clock to the PFD. Division ratios from 1 to 1023 are allowed. PHASE FREQUENCY DETECTOR (PFD) AND HIGH VOLTAGE CHARGE PUMP The phase frequency detector (PFD) takes inputs from the R counter and N counter and produces an output proportional to the phase and frequency difference between them. Figure 16 is a simplified schematic of the phase frequency detector. HIGH MOD VALUE D1 Q1 UP U1 FRAC VALUE +IN CLR1 09058-011 INT VALUE (2) Integer-N Mode SW2 REFIN NC fPFD = REFIN × [(1 + D)/(R × (1 + T))] DELAY Figure 15. RF N Divider U3 CHARGE PUMP CPOUT INT, FRAC, MOD, and R Counter Relationship HIGH U2 –IN Figure 16. PFD Simplified Schematic The RF VCO frequency (RFOUT) equation is RFOUT = (fPFD/RF Divider) × [INT + (FRAC/MOD)] CLR2 DOWN D2 Q2 09058-012 The INT, FRAC, and MOD values, in conjunction with the R counter, make it possible to generate output frequencies that are spaced by fractions of the PFD frequency. For more information, see the RF Synthesizer—A Worked Example section. (1) where: RFOUT is the output frequency of the external voltage controlled oscillator (VCO). RF Divider is the output divider that divides down the VCO frequency. INT is the preset divide ratio of the binary 16-bit counter (23 to 32,767 for the 4/5 prescaler, 75 to 65,535 for the 8/9 prescaler). FRAC is the numerator of the fractional division (0 to MOD − 1). MOD is the preset fractional modulus (2 to 4095). The PFD includes a delay element that sets the width of the antibacklash pulse to 4.2 ns. This pulse ensures that there is no dead zone in the PFD transfer function and provides a consistent reference spur level. The high voltage charge pump is designed on an Analog Devices, Inc., proprietary high voltage process and allows the charge pump to output voltages as high as 29 V when powered by a 30 V supply. The high voltage charge pump removes the need for active filtering when interfacing to a high voltage VCO. Rev. 0 | Page 11 of 28 ADF4150HV MUXOUT AND LOCK DETECT PROGRAM MODES The multiplexer output on the ADF4150HV allows the user to access various internal points on the chip. The state of MUXOUT is controlled by the M3, M2, and M1 bits in Register 2 (see Figure 22). Figure 17 shows the MUXOUT section in block diagram form. Table 6 and Figure 19 through Figure 25 show how the program modes are set up in the ADF4150HV. R COUNTER INPUT DVDD THREE-STATE-OUTPUT DVDD 1. GND R COUNTER OUTPUT The following settings in the ADF4150HV are double buffered: phase value, modulus value, reference doubler, reference divideby-2, R counter value, and charge pump current setting. Before the part uses a new value for any double-buffered setting, the following two events must occur: MUX MUXOUT CONTROL 2. N COUNTER OUTPUT ANALOG LOCK DETECT DIGITAL LOCK DETECT GND 09058-013 RESERVED Figure 17. MUXOUT Schematic The new value is latched into the device by writing to the appropriate register. A new write is performed on Register 0 (R0). For example, any time that the modulus value is updated, Register 0 (R0) must be written to, to ensure that the modulus value is loaded correctly. The divider select value in Register 4 (R4) is also double buffered, but only if the DB13 bit of Register 2 (R2) is high. INPUT SHIFT REGISTERS OUTPUT STAGE The ADF4150HV digital section includes a 10-bit RF R counter, a 16-bit RF N counter, a 12-bit FRAC counter, and a 12-bit modulus counter. Data is clocked into the 32-bit shift register on each rising edge of CLK. The data is clocked in MSB first. Data is transferred from the shift register to one of six latches on the rising edge of LE. The destination latch is determined by the state of the three control bits (C3, C2, and C1) in the shift register. As shown in Figure 2, the control bits are the three LSBs: DB2, DB1, and DB0. The truth table for these bits is shown in Table 6. Figure 19 summarizes how the latches are programmed. The RFOUT+ and RFOUT− pins of the ADF4150HV are connected to the collectors of an NPN differential pair driven by buffered outputs of the VCO, as shown in Figure 18. To allow the user to optimize the power dissipation vs. output power requirements, the tail current of the differential pair is programmable using Bits[DB4:DB3] in Register 4 (R4). Four current levels can be set. These levels give output power levels of −4 dBm, −1 dBm, +2 dBm, and +5 dBm, respectively, using a 50 Ω resistor to AVDD and ac coupling into a 50 Ω load. Alternatively, both outputs can be combined in a 1 + 1:1 transformer or a 180° microstrip coupler (see the Output Matching section). If the outputs are used individually, the optimum output stage consists of a shunt inductor to AVDD. Table 6. Truth Table for C3, C2, and C1 Control Bits Control Bits C2 0 0 1 1 0 0 C1 0 1 0 1 0 1 Register Register 0 (R0) Register 1 (R1) Register 2 (R2) Register 3 (R3) Register 4 (R4) Register 5 (R5) RFOUT+ VCO RFOUT – BUFFER/ DIVIDE-BY-1/-2/-4/-8/-16 09058-014 C3 0 0 0 0 1 1 Figure 18. Output Stage Another feature of the ADF4150HV is that the supply current to the RF output stage can be shut down until the part achieves lock, as measured by the digital lock detect circuitry. This feature is enabled by the mute-till-lock detect (MTLD) bit in Register 4 (R4). Rev. 0 | Page 12 of 28 ADF4150HV REGISTER MAPS RESERVED REGISTER 0 16-BIT INTEGER VALUE (INT) CONTROL BITS 12-BIT FRACTIONAL VALUE (FRAC) DB31 DB30 DB29 DB28 DB27 DB26 DB25 DB24 DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 0 N16 N15 N14 N13 N12 N11 N10 N9 N8 N7 N6 N5 N4 N3 N2 N1 F12 F11 F10 F9 F8 F7 F6 F5 F4 F3 F2 F1 DB2 DB1 DB0 C3(0) C2(0) C1(0) PRESCALER REGISTER 1 RESERVED DBR1 12-BIT PHASE VALUE (PHASE) CONTROL BITS DBR 1 12-BIT MODULUS VALUE (MOD) P10 P9 P8 P7 P6 P5 P4 P3 P2 P1 M12 M11 M10 M9 M8 M7 M6 M5 M4 M3 M2 M1 C3(0) C2(0) C1(1) COUNTER RESET P11 CP THREESTATE P12 POWER-DOWN PR1 DB0 RESERVED 0 DB1 LDP 0 DB2 LDF 0 RESERVED 0 DOUBLE BUFFER DB31 DB30 DB29 DB28 DB27 DB26 DB25 DB24 DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 CONTROL BITS MUXOUT DBR 1 DBR 1 RDIV2 LOW NOISE AND LOW SPUR MODES REFERENCE DOUBLER DBR 1 RESERVED REGISTER 2 10-BIT R COUNTER DBR 1 CHARGE PUMP CURRENT SETTING DB31 DB30 DB29 DB28 DB27 DB26 DB25 DB24 DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 0 L2 L1 M3 M2 M1 RD2 RD1 R10 R9 R8 R7 R6 R5 R4 R3 R2 R1 D1 0 CP3 CP2 CP1 U6 U5 1 U3 U2 U1 DB2 DB1 DB0 C3(0) C2(1) C1(0) RESERVED RESERVED BOOST EN REGISTER 3 CLK DIV MODE CONTROL BITS 12-BIT CLOCK DIVIDER VALUE DB31 DB30 DB29 DB28 DB27 DB26 DB25 DB24 DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 0 0 0 0 0 0 0 0 0 0 0 0 0 B1 0 C2 C1 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 DB2 DB1 DB0 C3(0) C2(1) C1(1) DBB 2 DIVIDER SELECT MTLD RESERVED RF OUTPUT ENABLE FEEDBACK SELECT REGISTER 4 RESERVED RESERVED OUTPUT POWER DB31 DB30 DB29 DB28 DB27 DB26 DB25 DB24 DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 0 0 0 0 0 0 0 0 D13 D12 D11 D10 0 0 0 0 0 0 0 0 0 D8 0 0 0 0 D3 D2 D1 CONTROL BITS DB2 DB1 DB0 C3(1) C2(0) C1(0) LD PIN MODE RESERVED CONTROL BITS RESERVED DB31 DB30 DB29 DB28 DB27 DB26 DB25 DB24 DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 ABP2 ABP1 CE1 C3(1) C2(0) C1(1) 1 0 0 0 0 D15 D14 0 0 0 0 0 0 0 0 0 0 0 0 0 1DBR = DOUBLE BUFFERED REGISTER—BUFFERED BY THE WRITE TO REGISTER 0. 2DBB = DOUBLE BUFFERED BITS—BUFFERED BY THE WRITE TO REGISTER 0, IF AND ONLY IF DB13 OF REGISTER 2 IS HIGH. Figure 19. Register Summary Rev. 0 | Page 13 of 28 0 0 0 0 0 0 DB1 DB0 09058-015 RESERVED CC ENABLE ABP WIDTH REGISTER 5 RESERVED ADF4150HV 16-BIT INTEGER VALUE (INT) DB31 DB30 DB29 DB28 DB27 DB26 DB25 DB24 DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 N16 N15 N14 N13 N12 N11 N10 N9 N8 N7 N6 N5 N4 N3 N2 N1 F12 F11 F10 F9 F8 F7 F6 DB7 DB6 F5 F4 DB5 DB4 F3 F2 DB3 F1 DB2 DB1 DB0 C3(0) C2(0) C1(0) N16 N15 ... N5 N4 N3 N2 N1 INTEGER VALUE (INT) F12 F11 ... F2 F1 FRACTIONAL VALUE (FRAC) 0 0 ... 0 0 0 0 0 NOT ALLOWED 0 0 ... 0 0 0 0 0 ... 0 0 0 0 1 NOT ALLOWED 0 0 ... 0 1 1 0 0 ... 0 0 0 1 0 NOT ALLOWED 0 0 ... 1 0 2 . . ... . . . . . ... 0 0 ... 1 1 3 0 0 ... 1 0 1 1 0 NOT ALLOWED . . ... . . . 0 0 ... 1 0 1 1 1 23 . . ... . . . 0 0 ... 1 1 0 0 0 24 . . ... . . . . . ... . . . . . ... 1 1 ... 0 0 4092 1 1 ... 1 1 1 0 1 65,533 1 1 ... 0 1 4093 1 1 ... 1 1 1 1 0 65,534 1 1 ... 1 0 4094 1 1 ... 1 1 1 1 1 65,535 1 1 ... 1 1 4095 09058-016 0 CONTROL BITS 12-BIT FRACTIONAL VALUE (FRAC) INTmin = 75 WITH PRESCALER = 8/9 PRESCALER Figure 20. Register 0 (R0) RESERVED DBR 12-BIT PHASE VALUE (PHASE) DB31 DB30 DB29 DB28 DB27 DB26 DB25 DB24 DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 0 0 0 PR1 P12 P11 P10 P9 P8 P7 P6 P5 P4 P3 P2 P1 M12 M11 M10 M9 M8 M7 M6 DB7 DB6 M5 M4 P1 PRESCALER P12 P11 ... P2 P1 PHASE VALUE (PHASE) M12 M11 ... M2 M1 0 4/5 0 0 ... 0 0 0 0 0 ... 1 0 2 1 8/9 0 0 ... 0 1 1 (RECOMMENDED) 0 0 ... 1 1 3 0 0 ... 1 0 2 . . ... . . . 0 0 ... 1 1 3 . . ... . . . . . ... . . . . . ... . . . 1 1 0 0 4092 . . ... . . . ... 1 1 ... 0 1 4093 . . ... . . . 1 1 ... 1 0 4094 1 1 ... 0 0 4092 1 1 ... 1 1 4095 1 1 ... 0 1 4093 1 1 ... 1 0 4094 1 1 ... 1 1 4095 DB5 DB4 M3 M2 DB3 M1 DB2 DB1 DB0 C3(0) C2(0) C1(1) INTERPOLATOR MODULUS (MOD) 09058-017 0 CONTROL BITS DBR 12-BIT MODULUS VALUE (MOD) Figure 21. Register 1 (R1) Rev. 0 | Page 14 of 28 COUNTER RESET CP THREESTATE POWER-DOWN LDP RESERVED CHARGE PUMP CURRENT SETTING LDF DBR RESERVED DBR 10-BIT R COUNTER DOUBLE BUFFER MUXOUT DBR RDIV2 LOW NOISE AND LOW SPUR MODES REFERENCE DOUBLER DBR RESERVED ADF4150HV DB31 DB30 DB29 DB28 DB27 DB26 DB25 DB24 DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 0 L2 L1 M3 M2 M1 RD2 RD1 R10 L2 L1 NOISE MODE RD2 REFERENCE DOUBLER 0 0 LOW NOISE MODE 0 DISABLED 0 1 RESERVED 1 ENABLED 1 0 RESERVED 1 1 LOW SPUR MODE R9 R8 R7 R6 R5 1 0 2 . . ... . . . . . ... . . . . . ... . . . 1 1 ... 0 0 1020 1 1 ... 0 1 1021 1 1 ... 1 0 1022 1 1 ... 1 1 1023 THREE-STATE OUTPUT 1 DVDD DB2 DB1 DB0 C3(0) C2(1) C1(0) 0 DISABLED 0 DISABLED 1 ENABLED 1 INT-N 1 ENABLED 48 96 144 192 240 288 336 384 1 U1 COUNTER RESET ICP (µA) 5.1kΩ 1 U2 U1 CP1 0 U3 FRAC-N 0 1 0 1 0 1 0 1 ... 1 LDF 0 0 1 1 0 0 1 1 ... U5 0 CP2 0 U6 U6 0 0 0 0 1 1 1 1 0 CP1 DOUBLE BUFFER R4[DB22:DB20] CP3 0 0 CP2 ENABLED 0 0 CP3 DISABLED R COUNTER (R) 0 0 1 R1 M1 D1 0 R2 M2 R1 REFERENCE DIVIDE-B Y-2 ... 0 R2 RD1 R9 0 R3 D1 R10 M3 R4 CONTROL BITS U5 LDP U2 CP THREE-STATE 0 10ns 0 DISABLED 1 6ns 1 ENABLED RESERVED BIT U3 POWER-DOWN 0 DISABLED 0 RESERVED 1 ENABLED 1 NORMAL OPERATION OUTPUT 0 1 0 GND 0 1 1 R COUNTER OUTPUT 1 0 0 N DIVIDER OUTPUT 1 0 1 1 1 0 DIGITAL LOCK DETECT 1 1 1 RESERVED 09058-018 ANALOG LOCK DETECT RESERVED CLK DIV MODE DB31 DB30 DB29 DB28 DB27 DB26 DB25 DB24 DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 0 0 0 0 0 0 0 0 0 0 0 0 0 B1 0 C2 C1 CONTROL BITS 12-BIT CLOCK DIVIDER VALUE D12 D11 D10 D9 D8 D7 D6 DB7 DB6 D5 D4 DB5 DB4 D3 D2 DB3 D1 B1 BOOST ENABLE D12 D11 ... D2 D1 CLOCK DIVIDER VALUE 0 0 ... 0 0 0 0 DISABLED 0 0 ... 0 1 1 1 ENABLED 0 0 ... 1 0 2 0 0 ... 1 1 3 . . ... . . . . . ... . . . . . ... . . . C2 C1 CLOCK DIVIDER MODE 0 0 CLOCK DIVIDER OFF 1 1 ... 0 0 4092 0 1 RESERVED 1 1 ... 0 1 4093 1 0 RESYNC ENABLE 1 1 ... 1 0 4094 1 1 RESERVED 1 1 ... 1 1 4095 Figure 23. Register 3 (R3) Rev. 0 | Page 15 of 28 DB2 DB1 DB0 C3(0) C2(1) C1(1) 09058-019 BOOST EN RESERVED Figure 22. Register 2 (R2) DBB DIVIDER SELECT MTLD RESERVED RF OUTPUT ENABLE FEEDBACK SELECT ADF4150HV RESERVED RESERVED OUTPUT POWER CONTROL BITS DB31 DB30 DB29 DB28 DB27 DB26 DB25 DB24 DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 0 0 0 0 0 0 0 D13 D12 D11 D10 0 0 0 0 0 0 0 0 0 D8 0 0 0 0 D3 D2 FEEDBACK D13 SELECT 0 DIVIDED FUNDAMENTAL 1 D12 D11 D10 RF DIVIDER SELECT 0 0 0 ÷1 0 0 1 ÷2 0 1 0 ÷4 0 1 1 ÷8 1 0 0 ÷16 D1 DB2 DB1 DB0 C3(1) C2(0) C1(0) D2 D1 OUTPUT POWER (dBm) 0 0 –4 0 1 –1 1 0 +2 1 1 +5 D8 MUTE TILL LOCK DETECT 0 MUTE DISABLED D3 RF OUT 1 MUTE ENABLED 0 DISABLED 1 ENABLED 09058-020 0 ABP WIDTH RESERVED CC ENABLE Figure 24. Register 4 (R4) LD PIN MODE RESERVED CONTROL BITS RESERVED DB31 DB30 DB29 DB28 DB27 DB26 DB25 DB24 DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 ABP2 ABP1 CE1 1 0 0 0 0 D15 D14 0 0 D15 D14 LOCK DETECT PIN OPERATION 0 0 OUTPUT LOW 0 1 DIGITAL LOCK DETECT1 1 0 OUTPUT LOW 1 1 OUTPUT HIGH 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 DB3 0 DB2 DB1 DB0 C3(1) C2(0) C1(1) RESERVED BIT RESERVED 1 NORMAL OPERATION CHARGE CANCELL ATION 0 DISABLED 1 ENABLED ABP2 ABP1 ANTIBACKLASH PULSE WIDTH 0 0 0 1 4.2ns (RECOMMENDED) RESERVED 1 0 RESERVED 1 1 RESERVED 1MUXOUT 09058-021 CE1 0 IN REGISTER 2 MUST ALSO BE SET TO DIGITAL LOCK DETECT FOR THE LOCK DETECT PIN TO OPERATE CORRECTLY. Figure 25. Register 5 (R5) Rev. 0 | Page 16 of 28 ADF4150HV In most applications, the phase relationship between the RF signal and the reference is not important. In such applications, the phase value can be used to optimize the fractional and subfractional spur levels. For more information, see the Spur Consistency and Fractional Spur Optimization section. REGISTER 0 Control Bits When Bits[C3:C1] are set to 000, Register 0 is programmed. Figure 20 shows the input data format for programming this register. If neither the phase resync nor the spurious optimization function is used, it is recommended that the phase word be set to 1. 16-Bit Integer Value (INT) The 16 INT bits (Bits[DB30:DB15]) set the INT value, which determines the integer part of the feedback division factor. The INT value is used in Equation 1 (see the INT, FRAC, MOD, and R Counter Relationship section). Integer values from 23 to 32,767 are allowed for the 4/5 prescaler; for the 8/9 prescaler, the minimum integer value is 75 and the maximum value is 65,535. 12-Bit Modulus Value (MOD) The 12 MOD bits (Bits[DB14:DB3]) set the fractional modulus. The fractional modulus is the ratio of the PFD frequency to the channel step resolution on the RF output. For more information, see the 12-Bit Programmable Modulus section. REGISTER 2 12-Bit Fractional Value (FRAC) Control Bits The 12 FRAC bits (Bits[DB14:DB3]) set the numerator of the fraction that is input to the Σ-Δ modulator. This fraction, along with the INT value, specifies the new frequency channel that the synthesizer locks to, as shown in the RF Synthesizer—A Worked Example section. FRAC values from 0 to (MOD − 1) cover channels over a frequency range equal to the PFD reference frequency. When Bits[C3:C1] are set to 010, Register 2 is programmed. Figure 22 shows the input data format for programming this register. REGISTER 1 Control Bits When Bits[C3:C1] are set to 001, Register 1 is programmed. Figure 21 shows the input data format for programming this register. Prescaler Value The dual-modulus prescaler, along with the INT, FRAC, and MOD values, determines the overall division ratio from the VCO output to the PFD input. The PR1 bit (DB27) in Register 1 sets the prescaler value. Operating at CML levels, the prescaler takes the clock from the VCO output and divides it down for the counters. The prescaler is based on a synchronous 4/5 core. When the prescaler is set to 4/5, the maximum RF frequency allowed is 3 GHz. Therefore, when operating the ADF4150HV above 3 GHz, the prescaler must be set to 8/9. The prescaler limits the INT value as follows: • • Prescaler = 4/5: NMIN = 23 Prescaler = 8/9: NMIN = 75 Low Noise and Low Spur Modes The noise modes on the ADF4150HV are controlled by setting Bits[DB30:DB29] in Register 2 (see Figure 22). The noise modes allow the user to optimize a design either for improved spurious performance or for improved phase noise performance. When the low spur mode is chosen, dither is enabled. Dither randomizes the fractional quantization noise so that it resembles white noise rather than spurious noise. As a result, the part is optimized for improved spurious performance. Low spur mode is normally used for fast-locking applications when the PLL closed-loop bandwidth is wide. Wide loop bandwidth is a loop bandwidth greater than 1/10 of the RFOUT channel step resolution (fRES). A wide loop filter does not attenuate the spurs to the same level as a narrow loop bandwidth. For best noise performance, use the low noise mode option. When the low noise mode is chosen, dither is disabled. This mode ensures that the charge pump operates in an optimum region for noise performance. Low noise mode is extremely useful when a narrow loop filter bandwidth is available. The synthesizer ensures extremely low noise, and the filter attenuates the spurs. Figure 8 and Figure 9 show fractional spur levels when using low spur mode and low noise mode. Figure 12 shows the in-band phase noise when using low spur mode and low noise mode. 12-Bit Phase Value Bits[DB26:DB15] control the phase word. The word must be less than the MOD value programmed in Register 1. The phase word is used to program the RF output phase from 0° to 360° with a resolution of 360°/MOD. For more information, see the Phase Resync section. MUXOUT The on-chip multiplexer is controlled by Bits[DB28:DB26] (see Figure 22). Rev. 0 | Page 17 of 28 ADF4150HV Reference Doubler Lock Detect Precision (LDP) Setting the DB25 bit to 0 disables the doubler and feeds the REFIN signal directly into the 10-bit R counter. Setting this bit to 1 multiplies the REFIN frequency by a factor of 2 before feeding it into the 10-bit R counter. When the doubler is disabled, the REFIN falling edge is the active edge at the PFD input to the fractional synthesizer. When the doubler is enabled, both the rising and falling edges of REFIN become active edges at the PFD input. The lock detect precision bit (Bit DB7) sets the comparison window in the lock detect circuit. When DB7 is set to 0, the comparison window is 10 ns; when DB7 is set to 1, the window is 6 ns. The lock detect circuit goes high when n consecutive PFD cycles are less than the comparison window value; n is set by the LDF bit (DB8). For example, with DB8 = 0 and DB7 = 0, 40 consecutive PFD cycles of 10 ns or less must occur before digital lock detect goes high. The recommended settings for Bits[DB8:DB7] are listed in Table 7. When the doubler is enabled and the low spur mode is chosen, the in-band phase noise performance is sensitive to the REFIN duty cycle. The phase noise degradation can be as much as 5 dB for REFIN duty cycles outside a 45% to 55% range. The phase noise is insensitive to the REFIN duty cycle in the low noise mode and when the doubler is disabled. The maximum allowable REFIN frequency when the doubler is enabled is 30 MHz. RDIV2 Setting the DB24 bit to 1 inserts a divide-by-2 toggle flip-flop between the R counter and the PFD. This function allows a 50% duty cycle signal to appear at the PFD input, which is necessary when the charge pump boost mode is enabled (see the Boost Enable section). Table 7. Recommended LDF and LDP Bit Settings Mode Integer-N Fractional-N, Low Noise Mode Fractional-N, Low Spur Mode The 10-bit R counter (Bits[DB23:DB14]) allows the input reference frequency (REFIN) to be divided down to produce the reference clock to the PFD. Division ratios from 1 to 1023 are allowed. Double Buffer The DB13 bit enables or disables double buffering of Bits[DB22:DB20] in Register 4. For information about how double buffering works, see the Program Modes section. DB7 (LDP) 1 1 0 Power-Down (PD) The DB5 bit provides the programmable power-down mode. Setting this bit to 1 performs a power-down. Setting this bit to 0 returns the synthesizer to normal operation. In software powerdown mode, the part retains all information in its registers. The register contents are lost only if the supply voltages are removed. When power-down is activated, the following events occur: • 10-Bit R Counter DB8 (LDF) 1 0 0 • • • • Synthesizer counters are forced to their load state conditions. Charge pump is forced into three-state mode. Digital lock detect circuitry is reset. RFOUT buffers are disabled. Input registers remain active and capable of loading and latching data. Charge Pump Three-State Setting the DB4 bit to 1 puts the charge pump into three-state mode. This bit should be set to 0 for normal operation. Charge Pump Current Setting Counter Reset Bits[DB11:DB9] set the charge pump current. This value should be set to the charge pump current that the loop filter is designed with (see Figure 22). Lock Detect Function (LDF) The DB8 bit configures the lock detect function (LDF). The LDF controls the number of PFD cycles monitored by the lock detect circuit to ascertain whether lock has been achieved. When DB8 is set to 0, the number of PFD cycles monitored is 40. When DB8 is set to 1, the number of PFD cycles monitored is 5. It is recommended that the DB8 bit be set to 0 for fractional-N mode and 1 for integer-N mode. The DB3 bit is the reset bit for the R counter and the N counter of the ADF4150HV. When this bit is set to 1, the RF synthesizer N counter and R counter are held in reset. For normal operation, this bit should be set to 0. Rev. 0 | Page 18 of 28 ADF4150HV REGISTER 3 Divider Select Control Bits Bits[DB22:DB20] select the value of the output divider (see Figure 24). When Bits[C3:C1] are set to 011, Register 3 is programmed. Figure 23 shows the input data format for programming this register. Mute-Till-Lock Detect (MTLD) Boost Enable Setting the DB18 bit to 1 enables the charge pump boost mode. If boost mode is enabled, the narrow loop bandwidth is maintained for spur attenuation, but faster lock times are still possible. Boost mode speeds up locking significantly for higher values of PFD frequencies that normally have many cycle slips. When boost mode is enabled, an extra charge pump current cell is turned on. This cell outputs a constant current to the loop filter or removes a constant current from the loop filter (depending on whether the VCO tuning voltage needs to increase or decrease to acquire the new frequency) until VTUNE approaches the lock voltage. The boost current is then disabled and the charge pump current setting reverts to the user programmed value. Loop stability is maintained because the current is constant and is not pulsed, so there is no need to switch a compensating loop filter resistor in and out, as in standard fast lock modes. Note that the PFD requires a 45% to 55% duty cycle for the boost mode to operate correctly. This duty cycle can be guaranteed by setting the RDIV2 bit (DB24) in Register 2. Clock Divider Mode Bits[DB16:DB15] must be set to 10 to activate phase resync (see the Phase Resync section). Setting Bits[DB16:DB15] to 00 disables the clock divider (see Figure 23). When the DB10 bit is set to 1, the supply current to the RF output stage is shut down until the part achieves lock, as measured by the digital lock detect circuitry. RF Output Enable The DB5 bit enables or disables the primary RF output. If DB5 is set to 0, the primary RF output is disabled; if DB5 is set to 1, the primary RF output is enabled. Output Power Bits[DB4:DB3] set the value of the primary RF output power level (see Figure 24). REGISTER 5 Control Bits When Bits[C3:C1] are set to 101, Register 5 is programmed. Figure 25 shows the input data format for programming this register. Antibacklash Pulse Width Bits[DB31:DB30] set the PFD antibacklash pulse width. The recommended value for all operating modes is 4.2 ns (set Bits[DB31:DB30] to 00). Other antibacklash pulse width settings are reserved and are not recommended. Charge Cancellation Setting the DB29 bit to 1 enables charge pump charge cancellation. This has the effect of reducing PFD spurs in integer-N mode. In fractional-N mode, this bit should be set to 0. 12-Bit Clock Divider Value Bits[DB14:DB3] set the 12-bit clock divider value. This value is the timeout counter for activation of phase resync. For more information, see the Phase Resync section. REGISTER 4 Lock Detect Pin Operation Bits[DB23:DB22] set the operation of the lock detect (LD) pin (see Figure 25). REGISTER INITIALIZATION SEQUENCE Control Bits At initial power-up, after the correct application of voltages to the supply pins, the ADF4150HV registers should be started in the following sequence: When Bits[C3:C1] are set to 100, Register 4 is programmed. Figure 24 shows the input data format for programming this register. Feedback Select The DB23 bit selects the feedback from the VCO output to the N counter. When this bit is set to 1, the signal is taken directly from the VCO. When this bit is set to 0, the signal is taken from the output of the output dividers. The dividers enable coverage of the wide frequency band (31.25 MHz to 3.0 GHz). When the dividers are enabled and the feedback signal is taken from the output, the RF output signals of two separately configured PLLs are in phase. This is useful in some applications where the positive interference of signals is required to increase the power. 1. 2. 3. 4. 5. 6. Rev. 0 | Page 19 of 28 Register 5 Register 4 Register 3 Register 2 Register 1 Register 0 ADF4150HV RF SYNTHESIZER—A WORKED EXAMPLE The following equations are used to program the ADF4150HV synthesizer: RFOUT = [INT + (FRAC/MOD)] × (fPFD/RF Divider) (3) (4) where: REFIN is the reference frequency input. D is the RF REFIN doubler bit (0 or 1). R is the RF reference division factor (1 to 1023). T is the reference divide-by-2 bit (0 or 1). The choice of modulus (MOD) depends on the reference signal (REFIN) available and the channel resolution (fRES) required at the RF output. For example, a GSM system with 13 MHz REFIN sets the modulus to 65. This means that the RF output resolution (fRES) is the 200 kHz (13 MHz/65) necessary for GSM. With dither off, the fractional spur interval depends on the modulus values chosen (see Table 8). 1.5 GHz VCO in fundamental mode 3 GHz VCO with the RF divider set to 2 When enabling the RF divider, the user must decide whether to close the PLL loop before the RF divider or after it. In this example, the PLL loop is closed before the RF divider (see Figure 26). PFD VCO ÷2 RFOUT N DIVIDER Figure 26. PLL Loop Closed Before Output Divider To minimize VCO feedthrough, the 3 GHz VCO is selected. A channel resolution (fRESOUT) of 500 kHz is required at the output of the RF divider. Therefore, the channel resolution at the output of the VCO (fRES) needs to be 2 × fRESOUT, that is, 1 MHz. MOD = REFIN/fRES MOD = 25 MHz/1 MHz = 25 For example, consider an application that requires a 1.75 GHz RF frequency output with a 200 kHz channel step resolution. The system has a 13 MHz reference signal. Another possible setup is to use the reference doubler to create 26 MHz from the 13 MHz input signal. The 26 MHz is then fed into the PFD, and the modulus is programmed to divide by 130. This setup also results in 200 kHz resolution but offers superior phase noise performance over the first setup. The programmable modulus is also very useful for multistandard applications with different channel spacing requirements. From Equation 4, fPFD = [25 MHz × (1 + 0)/1] = 25 MHz (5) 1500.5 MHz = 25 MHz × [(INT + (FRAC/25))/2] (6) where: INT = 120. FRAC = 1. RF Divider = 2. Unlike most other fractional-N PLLs, the ADF4150HV allows the user to program the modulus over a 12-bit range. When combined with the reference doubler and the 10-bit R counter, the 12-bit modulus allows the user to set up the part in many different configurations for the application. One possible setup is to feed the 13 MHz reference signal directly into the PFD and to program the modulus to divide by 65. This setup results in the required 200 kHz resolution. 09058-022 fPFD The reference divide-by-2 divides the reference signal by 2, resulting in a 50% duty cycle PFD frequency. This is necessary for the correct operation of the charge pump boost mode. For more information, see the Boost Enable section. 12-BIT PROGRAMMABLE MODULUS In this example, the user wants to program a 1.5 GHz RF frequency output (RFOUT) with a 500 kHz channel resolution (fRESOUT) required on the RF output. The reference frequency input (REFIN) is 25 MHz. The VCO options available to the user include the following: • • REFERENCE DOUBLER AND REFERENCE DIVIDER The on-chip reference doubler allows the input reference signal to be doubled. Doubling the reference signal doubles the PFD comparison frequency, which improves the noise performance of the system. Doubling the PFD frequency usually improves noise performance by 3 dB. Note that the PFD cannot operate above 32 MHz due to a limitation in the speed of the Σ-Δ circuit of the N divider. where: RFOUT is the RF frequency output. INT is the integer division factor. FRAC is the fractionality. MOD is the modulus. RF Divider is the output divider that divides down the VCO frequency. fPFD = REFIN × [(1 + D)/(R × (1 + T))] The ADF4150HV evaluation software can be used to help determine integer and fractional values for a given setup, along with the actual register settings to be programmed. It is important that the PFD frequency remain constant (in this example, 13 MHz). This allows the user to design one loop filter for both setups without encountering stability issues. Note that the ratio of the RF frequency to the PFD frequency principally affects the loop filter design, not the actual channel spacing. Rev. 0 | Page 20 of 28 ADF4150HV SPURIOUS OPTIMIZATION AND BOOST MODE Integer Boundary Spurs Narrow loop bandwidths can filter unwanted spurious signals, but these bandwidths usually have a long lock time. A wider loop bandwidth achieves faster lock times, but may lead to increased spurious signals inside the loop bandwidth. Another mechanism for fractional spur creation is the interactions between the RF VCO frequency and the reference frequency. When these frequencies are not integer related (the purpose of a fractional-N synthesizer), spur sidebands appear on the VCO output spectrum at an offset frequency that corresponds to the beat note, or difference frequency, between an integer multiple of the reference and the VCO frequency. These spurs are attenuated by the loop filter and are more noticeable on channels close to integer multiples of the reference where the difference frequency can be inside the loop bandwidth (thus the name integer boundary spurs). The boost mode feature can achieve the same fast lock time as the wider bandwidth, but with the advantage of a narrow final loop bandwidth to keep spurs low (see the Boost Enable section). SPUR MECHANISMS This section describes the three different spur mechanisms that arise with a fractional-N synthesizer and how to minimize them in the ADF4150HV. Fractional Spurs The fractional interpolator in the ADF4150HV is a third-order Σ-Δ modulator with a modulus (MOD) that is programmable to any integer value from 2 to 4095. In low spur mode (dither on), the minimum allowable value of MOD is 50. The Σ-Δ modulator is clocked at the PFD reference rate (fPFD), which allows PLL output frequencies to be synthesized at a channel step resolution of fPFD/MOD. In low noise mode (dither off), the quantization noise from the Σ-Δ modulator appears as fractional spurs. The interval between spurs is fPFD/L, where L is the repeat length of the code sequence in the digital Σ-Δ modulator. For the third-order Σ-Δ modulator used in the ADF4150HV, the repeat length depends on the value of MOD, as listed in Table 8. Table 8. Fractional Spurs with Dither Off (Low Noise Mode) MOD Value (Dither Off) MOD is divisible by 2, but not by 3 MOD is divisible by 3, but not by 2 MOD is divisible by 6 MOD is not divisible by 2, 3, or 6 Repeat Length 2 × MOD 3 × MOD 6 × MOD MOD Spur Interval Channel step/2 Channel step/3 Channel step/6 Channel step Reference Spurs Reference spurs are generally not a problem in fractional-N synthesizers because the reference offset is far outside the loop bandwidth. However, any reference feedthrough mechanism that bypasses the loop may cause a problem. The PCB layout must ensure adequate isolation between VCO traces and the input reference to avoid a possible feedthrough path on the board. SPUR CONSISTENCY AND FRACTIONAL SPUR OPTIMIZATION With dither off, the fractional spur pattern due to the quantization noise of the Σ-Δ modulator also depends on the particular phase word with which the modulator is seeded. The phase word can be varied to optimize the fractional and subfractional spur levels on any particular frequency. Thus, a lookup table of phase values corresponding to each frequency can be constructed for use when programming the ADF4150HV. If a lookup table is not used, keep the phase word at a constant value to ensure consistent spur levels on any particular frequency. In low spur mode (dither on), the repeat length is extended to 221 cycles, regardless of the value of MOD, which makes the quantization error spectrum look like broadband noise. This may degrade the in-band phase noise at the PLL output by as much as 10 dB. For lowest noise, dither off is a better choice, particularly when the final loop bandwidth is low enough to attenuate even the lowest frequency fractional spur. Rev. 0 | Page 21 of 28 ADF4150HV The output of a fractional-N PLL can settle to any one of the MOD phase offsets with respect to the input reference, where MOD is the fractional modulus. The phase resync feature of the ADF4150HV produces a consistent output phase offset with respect to the input reference. This is necessary in applications where the output phase and frequency are important, such as digital beamforming. For information about how to program a specific RF output phase when using phase resync, see the Phase Programmability section. In the example shown in Figure 27, the PFD reference is 25 MHz and MOD is 125 for a 200 kHz channel spacing. tSYNC is set to 400 μs by programming CLK_DIV_VALUE = 80. LE SYNC (INTERNAL) tSYNC LAST CYCLE SLIP FREQUENCY PLL SETTLES TO INCORRECT PHASE Phase resync is enabled by setting Bits[DB16:DB15] in Register 3 to 10. When phase resync is enabled, an internal timer generates sync signals at intervals of tSYNC given by the following formula: PLL SETTLES TO CORRECT PHASE AFTER RESYNC PHASE tSYNC = CLK_DIV_VALUE × MOD × tPFD –100 where: CLK_DIV_VALUE is the decimal value programmed in Bits[DB14:DB3] of Register 3 and can be any integer in the range of 1 to 4095. MOD is the modulus value programmed in Bits[DB14:DB3] of Register 1. tPFD is the PFD reference period. 0 100 200 300 400 500 600 TIME (µs) 700 800 900 1000 09058-025 PHASE RESYNC Figure 27. Phase Resync Example Phase Programmability The phase word in Register 1 controls the RF output phase. As this word is swept from 0 to MOD, the RF output phase sweeps over a 360° range in steps of 360°/MOD. When a new frequency is programmed, the second sync pulse after the LE rising edge is used to resynchronize the output phase to the reference. The tSYNC time must be programmed to a value that is at least as long as the worst-case lock time. This guarantees that the phase resync occurs after the last cycle slip in the PLL settling transient. Rev. 0 | Page 22 of 28 ADF4150HV APPLICATIONS INFORMATION ULTRAWIDEBAND PLL MICROWAVE PLL When paired with an octave tuning range VCO, the ADF4150HV provides an ultrawideband PLL function using the on-board RF dividers. With an octave tuning range at the fundamental frequency, the RF dividers provide full frequency coverage with no gaps down to much lower frequencies. The ADF4150HV can be interfaced directly to a wide tuning range microwave VCO without the need for an active filter. Typically, most microwave VCOs have a maximum tuning range of 15 V. In this case, set VP on the ADF4150HV to a value of 16 V or higher to ensure sufficient headroom in the charge pump. An external prescaler, such as the ADF5001, is required to divide down VCO frequencies that are above the maximum RF input frequency of 3.0 GHz. For example, using a 1 GHz to 2 GHz octave range VCO (such as the Synergy DCYS100200-12), the user can obtain contiguous output frequencies from 62.5 MHz to 2 GHz at the ADF4150HV RF outputs, as shown in Figure 28. A broadband output match is achieved using a 27 nH inductor in parallel with a 50 Ω resistor (for more information, see the Output Matching section). With such a wide output range, the same PLL hardware design can generate different frequencies for each of the different hardware platforms in the system. In the application circuit shown in Figure 29, the ADF5001 divides down the 16 GHz VCO signal to 4 GHz, which can then be input directly into the ADF4150HV RF inputs. The ADF5001 can be connected either single-ended or differentially to the ADF4150HV. For best performance and to achieve maximum power transfer, it is recommended that a differential connection be used. VDD ZBIAS RFOUT+ ZBIAS = 50Ω||27nH ADF4150HV PLL RFIN+ RFOUT– RFIN– CPOUT RFOUT = 62.5MHz TO 2GHz SYNERGY DCYS100200-12 OCTAVE RANGE VCO 37Ω VTUNE 150Ω 09058-026 150Ω RFOUT Figure 28. Ultrawideband PLL Using the ADF4150HV and an Octave Tuning Range VCO Rev. 0 | Page 23 of 28 ADF4150HV 10pF RFOUT AC COUPLING INTEGRATED ON ADF5001 DEVICE RFIN+ ADF4150HV ADF5001 PRESCALER RFIN GND PLL RFOUT MICROWAVE VCO 6dB PAD 37Ω 150Ω CPOUT RFIN– 18Ω 150Ω 18Ω RFOUT VTUNE 18Ω 16GHz OUT 09058-027 VDD1 VDD2 0.1µF Figure 29. 16 GHz Microwave PLL GENERATING THE HIGH VOLTAGE SUPPLY The design of the boost converter is simplified using the ADP161x Excel-based design tool. This tool is available from the ADP1613 product page. Figure 30 shows the user inputs for an example 5 V input to 20 V output design. To minimize voltage ripple at the output of the converter stage, the Noise Filter option is selected, and the Vout Ripple field is set to its minimum value. The high voltage charge pump current draw is 2 mA maximum; therefore, a value of 10 mA is entered in the Iout field to provide margin. When tested with the ADF4150HV evaluation board, this design showed no evident switching spurs at the VCO output. Rev. 0 | Page 24 of 28 09058-028 It is possible to use a boost converter such as the Analog Devices ADP1613 to generate the high voltage charge pump supply from a lower voltage rail without degrading PLL performance. To minimize any switching noise feedthrough, ensure that sufficient decoupling is placed close to the charge pump supply pin (Pin 6). Care should be taken to use capacitors with the appropriate voltage rating; for example, if using a boost converter to generate a 20 V VP supply, use capacitors with a rating of 20 V or higher. Figure 30. ADP161x Designer Tool ADF4150HV Blackfin ADSP-BF527 Interface INTERFACING TO THE ADuC702x AND THE ADSP-BF527 The ADF4150HV has a simple SPI-compatible serial interface for writing to the device. The CLK, DATA, and LE pins control the data transfer. When LE goes high, the 32 bits that were clocked into the appropriate register on each rising edge of CLK are transferred to the appropriate latch. See Figure 2 for the timing diagram and Table 6 for the register address table. Figure 32 shows the interface between the ADF4150HV and the Blackfin® ADSP-BF527 digital signal processor (DSP). The ADF4150HV needs a 32-bit serial word for each latch write. The easiest way to accomplish this using the Blackfin family is to use the autobuffered transmit mode of operation with alternate framing. This mode provides a means for transmitting an entire block of serial data before an interrupt is generated. ADuC702x Interface ADF4150HV The microcontroller is set up for SPI master mode with CPHA = 0. To initiate the operation, the I/O port driving LE is brought low. Each latch of the ADF4150HV needs a 32-bit word, which is accomplished by writing four 8-bit bytes from the microcontroller to the device. After the fourth byte is written, the LE input should be brought high to complete the transfer. ADF4150HV MOSI ADuC702x I/O PORTS CLK DATA LE MUXOUT (LOCK DETECT) MOSI DATA GPIO LE ADSP-BF527 I/O PORTS CE MUXOUT (LOCK DETECT) Figure 32. ADSP-BF527 to ADF4150HV Interface Set up the word length for eight bits and use four memory locations for each 32-bit word. To program each 32-bit latch, store the 8-bit bytes, enable the autobuffered mode, and write to the transmit register of the DSP. This last operation initiates the autobuffer transfer. If using a faster SPI clock, make sure that the SPI timing requirements listed in Table 2 are adhered to. PCB DESIGN GUIDELINES FOR A CHIP SCALE PACKAGE CE 09058-030 SCLOCK CLK 09058-031 Figure 31 shows the interface between the ADF4150HV and the ADuC702x family of analog microcontrollers. The ADuC702x family is based on an ARM7 core, but the same interface can be used with any 8051-based microcontroller. SCK Figure 31. ADuC702x to ADF4150HV Interface I/O port lines on the ADuC702x are also used to control the power-down input (CE) and the lock detect (MUXOUT configured for lock detect and polled by the port input). When operating in the mode described, the maximum SPI transfer rate of the ADuC7023 is 20 Mbps. This means that the maximum rate at which the output frequency can be changed is 833 kHz. If using a faster SPI clock, make sure that the SPI timing requirements listed in Table 2 are adhered to. The lands on the chip scale package (CP-32-11) are rectangular. The PCB pad for these lands must be 0.1 mm longer than the package land length and 0.05 mm wider than the package land width. Each land must be centered on the pad to ensure that the solder joint size is maximized. The bottom of the chip scale package has a central exposed thermal pad. The thermal pad on the PCB must be at least as large as the exposed pad. On the PCB, there must be a minimum clearance of 0.25 mm between the thermal pad and the inner edges of the pad pattern to ensure that shorting is avoided. Thermal vias can be used on the PCB thermal pad to improve the thermal performance of the package. If vias are used, they must be incorporated into the thermal pad at 1.2 mm pitch grid. The via diameter must be between 0.3 mm and 0.33 mm, and the via barrel must be plated with 1 oz. of copper to plug the via. Rev. 0 | Page 25 of 28 ADF4150HV OUTPUT MATCHING The output of the ADF4150HV can be matched in a number of ways for optimum operation; the most basic is to connect a 50 Ω resistor to AVDD. A dc bypass capacitor of 100 pF is connected in series, as shown in Figure 33. Because the resistor is not frequency dependent, this method provides a good broadband match. When connected to a 50 Ω load, this circuit typically gives a differential output power equal to the values chosen by Bits[DB4:DB3] in Register 4. The circuit shown in Figure 34 provides a good broadband match to 50 Ω for frequencies from 250 MHz to 3.0 GHz. The maximum output power in this case is approximately 5 dBm. The inductor can be increased for operation below 250 MHz. Both single-ended architectures can be examined using the EVAL-ADF4150HVEB1Z evaluation board. AVDD 22nH 1nF 50Ω RFOUT+ AV DD 50Ω 50Ω 100Ω 1nF 50Ω RFOUT– 50Ω Figure 33. Simple ADF4150HV Output Stage Another solution is to connect a shunt inductor (acting as an RF choke) to AVDD. This solution can help provide a better narrowband match and, therefore, more output power. However, because the output stage is open-collector, it is recommended that a termination resistor be used in addition to the RF choke to give a defined output impedance. The termination resistor can be either 50 Ω in parallel with the RF choke or 100 Ω connected across the RF output pins. 22nH AVDD 09058-032 50Ω 09058-029 100pF RFOUT Figure 34. Optimum ADF4150HV Output Stage If differential outputs are not needed, the unused output can be terminated, or both outputs can be combined using a balun. Rev. 0 | Page 26 of 28 ADF4150HV OUTLINE DIMENSIONS 0.30 0.25 0.18 32 25 0.50 BSC 0.80 0.75 0.70 0.50 0.40 0.30 8 16 0.05 MAX 0.02 NOM COPLANARITY 0.08 0.20 REF SEATING PLANE 3.65 3.50 SQ 3.45 EXPOSED PAD 17 TOP VIEW PIN 1 INDICATOR 1 24 9 BOTTOM VIEW 0.25 MIN 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-WHHD. 112408-A PIN 1 INDICATOR 5.10 5.00 SQ 4.90 Figure 35. 32-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 5 mm × 5 mm Body, Very Very Thin Quad (CP-32-11) Dimensions shown in millimeters ORDERING GUIDE Model 1 ADF4150HVBCPZ ADF4150HVBCPZ-RL7 EVAL-ADF4150HVEB1Z 1 Temperature Range −40°C to +85°C −40°C to +85°C Package Description 32-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 32-Lead Lead Frame Chip Scale Package [LFCSP_WQ] Evaluation Board Z = RoHS Compliant Part. Rev. 0 | Page 27 of 28 Package Option CP-32-11 CP-32-11 ADF4150HV NOTES ©2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D09058-0-8/11(0) Rev. 0 | Page 28 of 28