TRF3762 www.ti.com ....................................................................................................................................................... SLWS205A – JANUARY 2008 – REVISED MAY 2008 INTEGER-N PLL WITH INTEGRATED VCO REF To Microcontroller AVDD_REF AVDD_CP 35 34 33 32 31 30 GND AVDD GND 36 CPOUT REF_IN 37 MUX_OUT DVDD2 C2 39 38 GND 29 AVDD_BIAS CLOCK 3 28 RBIAS1 27 GND 26 VCTRL_IN 25 AVDD_VCO R3 2.37 kΩ DATA 4 STROBE 5 DGND 6 DGND 7 24 AVDD_BUF DVDD1 8 23 AVDD_CAPARRAY AVDD_PRES 9 22 GND R5 120 Ω 18 RSVD C7 1000 pF R6 120 Ω AVDD GND 16 17 21 19 20 RBIAS2 15 AVDD_VCOBUF 14 GND 12 13 AVDD_OUTBUF 10 11 VCO_OUTM GND TRF3762 (TOP VIEW) VCO_OUTP Wireless Infrastructure – WCDMA, CDMA, GSM – Wideband Transceivers – Wireless Local Loop – RFID Transceivers – Clock generation – IF LO generation C3 R1 2 APPLICATIONS • C1 C4 1000 pF (See Note A) CHIP_EN GND • • • • • • 40 1 PD_OUTBUF R2 GND • • • Fully Integrated VCO Low Phase Noise: –137dBc/Hz at 600kHz, fVCO of 1.9GHz Low Noise Floor: –158dBc/Hz at 10MHz Offset Integer-N PLL Input Reference Frequency range: 10MHz to 104MHz VCO Frequency Divided by 2-4 Output Output Buffer Enable Pin Programmable Charge Pump Current Hardware and Software Power Down 3-Wire Serial Interface Single Supply: 4.5V to 5.25V Operation To Microcontroller • • GND FEATURES 1 R4 4.75 kΩ VDD VDD C5 10 pF C6 10 pF LOAD A. See the Application Information section for Loop Filter Design procedures. AVAILABLE DEVICE OPTIONS PART NUMBER TRF3762-E Div by 1 Div by 2 Div by 4 Fstart Fstop Fstart Fstop Fstart Fstop 1805 1936 902.5 968 451.25 484 DESCRIPTION TRF3762-E is a high performance, highly integrated frequency synthesizer, optimized for high performance applications. The device includes a low-noise, voltage-controlled oscillator (VCO) and an integer-N PLL. TRF3762-E integrates divide-by 1, 2, or 4 options for a more flexible output frequency range. The device is controlled through a 3-wire serial-programming-interface (SPI) interface. For power sensitive applications, the device can be powered down by the SPI interface or externally via CHIP_EN (pin 2). The TRF3762-E offers the ability to reduce lock time when compared to the TRF3761-E device. The TRF3762-E was designed so that the external loop filter is the determining factor in the setting of lock time. Typical lock times for the TRF3762-E are less than 350µs (depending on the loop filter circuit). All other features of the TRF3762-E are identical to the TRF3761-E including superior phase noise and spurious output as well as the programming model and register mapping. The TRF3762-E is pin-to-pin compatible to the TRF3761-E. 1 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2008, Texas Instruments Incorporated TRF3762 SLWS205A – JANUARY 2008 – REVISED MAY 2008 ....................................................................................................................................................... www.ti.com This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. PACKAGE/ORDERING INFORMATION (1) (1) (2) PRODUCT PACKAGE LEAD PACKAGE DESIGNATOR (2) SPECIFIED TEMPERATURE RANGE PACKAGE MARKINGS TRF3762-E QFN-40 RHA –40°C to 85°C TRF3762-E ORDERING NUMBER TRANSPORT MEDIA, QUANTITY TRF3762-EIRHAR Tape and Reel, 2500 TRF3762-EIRHAT Tape and Reel, 250 For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI website at www.ti.com. Thermal pad size: 177 × 177 mils. 39 3 Lock Det STROBE DATA CLOCK MUX_OUT Functional Block Diagram 4 5 Serial Interface 38 R Div REF_IN PFD Charge Pump 34 CPOUT N−Divider B− counter A− counter 26 Prescaler div p/p+1 2 SPI From SPI From 13 VCO_OUTP Power Down RSVD 18 2 VCO_OUTM Submit Documentation Feedback 1 PD_OUTBUF CHIP_EN SPI From 14 Div1/2/4 VCTRL_IN Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 TRF3762 www.ti.com ....................................................................................................................................................... SLWS205A – JANUARY 2008 – REVISED MAY 2008 35 34 33 32 31 30 GND AVDD 36 CPOUT 37 GND AVDD_CP 39 38 GND 40 1 AVDD_REF PD_OUTBUF REF_IN DVDD2 MUX_OUT RHA PACKAGE (TOP VIEW) GND CHIP_EN 2 29 AVDD_BIAS CLOCK 3 28 RBIAS1 DATA 4 27 GND STROBE 5 26 VCTRL_IN DGND 6 25 AVDD_VCO 9 22 GND 15 16 17 18 AVDD GND 14 AVDD_VCOBUF 12 13 21 19 20 VCO_OUTP GND GND 10 11 RBIAS2 AVDD_PRES RSVD AVDD_CAPARRAY GND AVDD_BUF 23 AVDD_OUTBUF 24 8 VCO_OUTM 7 GND DGND DVDD1 TERMINAL FUNCTIONS TERMINAL (1) NAME NO. I/O DESCRIPTION PD_OUTBUF 1 I Once configured in register 1, this pin will control the output buffer. Logic level 0 turns on the buffer and logic level 1 turns off the buffer. CHIP_EN 2 I This pin requires 4.5 to 5.25V applied for normal operation. Grounding this pin will disable the chip. CLOCK 3 I Serial-programming-interface clock DATA 4 I/O 5 I STROBE Serial-programming-interface data, used for programming the frequency and other features. Serial-programming-interface strobe required to write the data to the chip DGND 6, 7 DVDD1 8 Digital power supply, requires 4.5 to 5.25V, Suggested decoupling, 0.1µF and 10pF capacitors in parallel. AVDD_PRES 9 Power supply for prescaler circuit, requires 4.5 to 5.25V, Suggested decoupling, 0.1µF and 10pF capacitors in parallel. VCO_OUTP 13 O VCO output, can be used single ended matched to 50Ω or in conjuction with VCO_OUTM (pin 14) with a balun. VCO_OUTM 14 O VCO output, can be used single ended matched to 50Ω or in conjunction with VCO_OUTP (pin 13) with a balun. AVDD_OUTBUF 15 Power supply for output buffers, requires 4.5 to 5.25V, Suggested decoupling, 0.1µF and 10pF capacitors in parallel. AVDD_VCOBUF 17 Power supply for VCO buffers, requires 4.5 to 5.25V, Suggested decoupling, 0.1µF and 10pF capacitors in parallel. RSVD 18 I Reserved for internal use, requires a 1000pF capacitor to ground for opperation. RBIAS2 19 I/O External bias resistor for setting the internal reference current requires a 4.75KΩ resister to ground. (1) Digital ground Power Supply = VCC = DVDD1, AVDD1, AVDD_PRES, AVDD_VCOBUF, AVDD, AVDD_CAPARRAY, AVDD_BUF, AVDD_VCO, AVDD_BIAS, AVDD_CP, AVDD_REF, DVDD2 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 3 TRF3762 SLWS205A – JANUARY 2008 – REVISED MAY 2008 ....................................................................................................................................................... www.ti.com TERMINAL FUNCTIONS (continued) TERMINAL (1) I/O DESCRIPTION NAME NO. AVDD 21 Analog power supply, requires 4.5 to 5.25 V, Suggested decoupling, 0.1µF and 10pF capacitors in parallel. AVDD_CAPARRAY 23 Power supply for VCO core and buffer, requires 4.5 to 5.25V, Suggested decoupling, 0.1µF and 10pF capacitors in parallel. AVDD_BUF 24 Power supply for VCO core and buffer, requires 4.5 to 5.25V, Suggested decoupling, 0.1µF and 10pF capacitors in parallel. AVDD_VCO 25 Power supply for VCO core and buffer, requires 4.5 to 5.25V, Suggested decoupling, 0.1µF and 10pF capacitors in parallel. VCTRL_IN 26 I RBIAS1 28 I/O AVDD_BIAS 29 VCO control voltage, the output of the loop filter is applied to this pin. External bias resistor for setting charge pump reference current, requires 2.37KΩ resistor to ground. Power supply for band gap current bias, requires 4.5 to 5.25V, Suggested decoupling, 0.1µF and 10pF capacitors in parallel. GND 10, 11, 12, 16, 20, 22, 27, 30, 31, 33, 37 AVDD 32 CPOUT 34 AVDD_CP 35 Analog power supply for charge pump, requires 4.5 to 5.25V, Suggested decoupling, 0.1µF and 10pF capacitors in parallel AVDD_REF 36 Power supply for REF_IN circuitry, requires 4.5 to 5.25V, Suggested decoupling, 0.1µF and 10pF capacitors in parallel. REF_IN 38 I Reference signal input, reference oscillator input of 10MHz to 104MHz. MUX_OUT 39 O Generally used for digital lock detect, can be used to verify locked condition by microcontroller, high = locked, low = unlocked. DVDD2 40 Analog ground Power supply for FUSE cell, requires 4.5 to 5.25V. Suggested decoupling, 0.1µF, 1nF and 1pF capacitors in parallel. O Charge pump output, connected to the input of loop filter. Power supply for the digital regulator, requires 4.5 to 5.25V, Suggested decoupling, 0.1µF and 10pF capacitors in parallel. THERMAL CHARACTERISTICS over operating free-air temperature range (unless otherwise noted) PARAMETER (1) TEST CONDITIONS MIN θJA (1) Thermal derating, junction-to-ambient TYP MAX UNIT 26 °C/W Soldered slug, 200-LFM airflow 20.1 °C/W Soldered slug, 400-LFM airflow 17.4 °C/W Soldered slug, no airflow Determined using JEDEC standard JESD-51 with High K board. ABSOLUTE MAXIMUM RATINGS Over operating free-air temperature range (unless otherwise noted) (1) Supply voltage range (2) Digital I/O voltage range VALUE UNIT –0.3 to 5.5 V –0.3 to VCC +0.3 V TJ Operating virtual junction temperature range –40 to 150 °C Tstg Storage temperature range –65 to 150 °C (1) (2) 4 Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating conditions is not implied. Exposure to absolute maximum rated conditions for extended periods may affect device reliability. All voltage values are with respect to network ground terminal. Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 TRF3762 www.ti.com ....................................................................................................................................................... SLWS205A – JANUARY 2008 – REVISED MAY 2008 RECOMMENDED OPERATING CONDITIONS Over operating free-air temperature range (unless otherwise noted) VCC Power supply voltage MIN NOM MAX 4.5 5 5.25 V 500 µVpp Power supply voltage ripple UNIT TA Operating free air temperature range –40 85 °C TJ Operating virtual junction temperature range –40 150 °C ELECTRICAL CHARACTERISTICS Supply voltage = VCC = 4.5V to 5.25V, TA = –40 to 85 °C (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT DC Parameters ICC Total supply current TA = 25°C Divide by 1 output 130 mA Divide by 2 output 140 mA Divide by 4 output 150 mA Reference Oscillator Parameters fref Reference frequency 10 104 MHz Reference input sensitivity (REF_IN) 0.5 2 VPP Reference input impedance (REF_IN) Parallel capacitance Parallel resistance 2 pF 3000 Ω PFD Charge Pump PFD frequency Charge pump current (ICP_OUT ) 30 SPI programmable 5.6 MHz mA Digital Interface (PD_OUTBUF, CHIP_EN, CLOCK, DATA, STROBE) VIH High-level input voltage 2.5 VCC V VIL Low-level input voltage 0 0.8 V VOH High-level output voltage VOL Low-level output voltage 0.8VCC V 0.2VCC V Output Power Single ended 0 dBm Differential 3 dBm TIMING REQUIREMENTS Supply voltage = VCC = 4.5V to 5.25V, TA = –40 to 85 °C PARAMETER TEST CONDITIONS MIN TYP MAX UNIT t(CLK) Clock period 50 ns tsu1 Setup time, data 10 ns th Hold time, data 10 ns tw Pulse width, STROBE 20 ns tsu2 Setup time, STROBE 10 ns Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 5 TRF3762 SLWS205A – JANUARY 2008 – REVISED MAY 2008 ....................................................................................................................................................... www.ti.com tsu1 th 1” Clock Pike t(CLK) CLOCK DATA DB0 (LSB) Address bit 1 DB1 Address bit 2 DB2 Address bit 3 DB29 Cmd bit 30 DB30 Cmd bit 31 DB31 (MSB) Cmd bit 32 tsu2 tw STROBE A. The first 4 bits, DB(3-0), of data are Address bits. The 28 remaining bits, DB(31-4), are part of the command. The command is little endian or lower bits first. Figure 1. Serial Programming Timing Diagram 6 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 TRF3762 www.ti.com ....................................................................................................................................................... SLWS205A – JANUARY 2008 – REVISED MAY 2008 TRF3762-E ELECTRICAL CHARACTERISTICS Supply voltage = VCC = 5V, TA = –40 to 85 °C (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT NOISE CHARACTERISTICS VCO phase noise, Free running VCO direct output fVCO = 1869MHz, fO = 1869MHz VCO phase noise, Free running VCO divide-by-2 output fVCO = 1869MHz, fO = 934.5MHz VCO phase noise, Free running VCO divide-by-4 output fVCO = 1869MHz, fO = 467.25MHz 100kHz offset -119.3 600kHz offset -137.3 1MHz offset -141.4 6MHz offset -154.1 10MHz offset -156 100kHz offset -124.4 600kHz offset -143 1MHz offset -146.7 6MHz offset -156.5 10MHz offset -156.7 100kHz offset -131 600kHz offset -149 1MHz offset -151 6MHz offset -155.8 10MHz offset -156.1 1kHz offset VCO phase noise, Closed loop phase noise direct output (1) (2) (3) fVCO = 1869MHz, fO = 1869MHz 100Hz to 10MHz VCO phase noise, Closed loop phase noise divide-by-2 output (1) (2) (3) fVCO = 1869MHz, fO = 934.5MHz -136.7 1MHz offset -141.6 600kHz offset 1MHz offset 10MHz offset 100Hz to 10MHz RMS phase error Closed loop phase noise divide-by-4 output (3) 100Hz to 10MHz VCO gain, Kv VCO free running Reference spur and multiples (1) (2) (3) fVCO = 1869MHz, fO = 467.25MHz dBc/Hz -156 -87.8 -142.6 -147 dBc/Hz -1567.6 0.521° 1kHz offset VCO phase noise, Closed loop phase noise divide-by-4 output (1) (2) (3) dBc/Hz 1.02° 1kHz offset RMS phase error Closed loop phase noise divide-by-2 output (3) dBc/Hz -82.5 600kHz offset 10MHz offset RMS phase error Closed loop phase noise direct output (3) dBc/Hz -92.9 600kHz offset -148.1 1MHz offset -151.4 10MHz offset -155.2 (2) dBc/Hz 0.251° 24 MHz/V -80 dBc See Application Circuit Figure 15. PFD = 200kHz, Loop Filter BW = 15kHz, Output frequency step = 200kHz. Reference oscillator RMS phase error = 0.008250°, RMS jitter = 881.764 fs. Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 7 TRF3762 SLWS205A – JANUARY 2008 – REVISED MAY 2008 ....................................................................................................................................................... www.ti.com TRF3762-E TYPICAL CHARACTERISTICS Closed Loop VCO Phase Noise Open Loop VCO Phase Noise −70 −70 CL = 1869 MHz −90 −100 −110 −120 −130 −140 −150 −160 1k −90 −100 −110 −120 −130 −140 −150 10k 100k −160 1k 10M 1M Figure 3. Open Loop VCO Phase Noise CL = 934.5 MHz OL = 934.5 MHz −80 −90 Phase Noise − dBc/Hz Phase Noise − dBc/Hz 10M −70 −100 −110 −120 −130 −140 −150 −90 −100 −110 −120 −130 −140 −150 10k 100k −160 1k 10M 1M 10k 100k 1M f − Frequency − Hz f − Frequency − Hz Figure 4. Figure 5. Closed Loop VCO Phase Noise 10M Open Loop VCO Phase Noise −70 −70 CL = 467.25 MHz −80 OL = 467.25 MHz −80 −90 Phase Noise − dBc/Hz Phase Noise − dBc/Hz 1M f − Frequency − Hz −80 −100 −110 −120 −130 −140 −150 8 100k Figure 2. Closed Loop VCO Phase Noise −160 1k 10k f − Frequency − Hz −70 −160 1k OL = 1869 MHz −80 Phase Noise − dBc/Hz Phase Noise − dBc/Hz −80 −90 −100 −110 −120 −130 −140 −150 10k 100k 1M 10M −160 1k 10k 100k f − Frequency − Hz f − Frequency − Hz Figure 6. Figure 7. Submit Documentation Feedback 1M 10M Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 TRF3762 www.ti.com ....................................................................................................................................................... SLWS205A – JANUARY 2008 – REVISED MAY 2008 TRF3762-E TYPICAL CHARACTERISTICS (continued) Direct Output: PFD Frequency Spurs Figure 8. Direct-By-2 Output: PFD Frequency Spurs Figure 9. Direct-By-4 Output: PFD Frequency Spurs Figure 10. Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 9 TRF3762 SLWS205A – JANUARY 2008 – REVISED MAY 2008 ....................................................................................................................................................... www.ti.com SERIAL INTERFACE PROGRAMMING REGISTERS DEFINITION The TRF3762 features a 3-wire serial programming interface that controls an internal, 32-bit shift register. There are a total of 3 signals that need to be applied: the CLOCK (pin 3), the serial DATA (pin 4) and the STROBE (pin 5). The DATA (DB0-DB31) is loaded LSB first and is read on the rising edge of the CLOCK. The STROBE is asynchronous to the CLOCK and at its rising edge the data in the shift register gets loaded onto the selected internal register. The first four bits (DB0-DB3) is the address to select the available internal registers. tsu1 th t(CLK) 1” Clock Pike CLOCK DATA DB0 (LSB) Address bit 1 DB1 Address bit 2 DB2 Address bit 3 DB29 Cmd bit 30 DB30 Cmd bit 31 DB31 (MSB) Cmd bit 32 tsu2 tw STROBE A. The first 4 bits, DB(3-0), of data are Address bits. The 28 remaining bits, DB(31-4), are part of the command. The command is little endian or lower bits first. Figure 11. Serial Programming Timing Diagram Register Address DB0 DB1 DB2 REST DB3 DB4 Charge Pump Current Select DB5 DB6 DB7 Output Mode DB8 DB9 Reference Clock Divider (RDiv) DB16 DB17 DB18 DB19 DB20 DB21 DB22 OUTBUF EN_SEL PD BUFOUT DB10 DB11 Anti Backlash DB23 DB24 DB25 DB26 DB27 Reference Clock Divider (RDiv) DB12 DB13 DB14 DB15 PFD_P OL TRIS_C P CP_TE ST Full Cal Req DB28 DB29 DB30 DB31 Figure 12. Register 1 10 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 TRF3762 www.ti.com ....................................................................................................................................................... SLWS205A – JANUARY 2008 – REVISED MAY 2008 Table 1. Register 1: Device Setup REGISTER 1 MAPPING Data Field Address Bits DB31 FULL_CAL_REQ This is a read only bit, that indicates if a power-up cal is required 0 power-up cal is not required 1 power-up cal is required DB30 CP_TEST TI internal use only 1 test enabled DB29 TRIS_CP High-impedance state charge pump output 1 CP high-impedance state 0 for normal operation DB28 PFD_POL Selects Polarity of PFD, should match polarity of VCO gain. If using external VCO with Negative gain then set to 0 and vise versa. The internal VCO has positive gain so set to positive(1) 0 negative 1 positive DB27 ABPW1 ABPW<1,0>: anti-backlash pulse width 00 01 10 11 DB26 ABPW0 DB25 RDIV_13 14-bit reference clock divider DB24 RDIV_12 RDIV<13,0>:00...01: divide by 1 RDIV<13,0>:00...10: divide by 2 RDIV<13,0>:00...11: divide by 3 DB23 RDIV_11 DB22 RDIV_10 DB21 RDIV_9 DB20 RDIV_8 DB19 RDIV_7 DB18 RDIV_6 DB17 RDIV_5 DB16 RDIV_4 DB15 RDIV_3 DB14 RDIV_2 DB13 RDIV_1 DB12 RDIV_0 DB11 PD_BUFOUT If DB10 = 0 then it controls power down of output buffer <DB10:11>: 00 default; output buffer on 01 output buffer off 1x output buffer on/off controlled by OUTBUF_EN pin DB10 OUTBUF_EN_SEL Select Output Buffer enable control: 0 internal 1 through OUTBUF_EN pin DB9 OUT_MODE_1 DB8 OUT_MODE_0 OUTBUFMODE<1,0>: Selection of RF output buffer division ratio 00 divide by 1 01 divide by 2 10 divide by 4 DB7 ICP2 DB6 ICP1 DB5 ICP0 DB4 RESET DB3 1.5ns 0.9ns 3.8ns 2.7ns delay delay delay delay ICP<2,0>: select charge pump current (1 mA step). From 1.4mA to 11.2mA with Rbias set to 2.37KΩ. Registers reset 1 high 0 low for normal operation Address Bits <3,0>=0000 for register 1 DB2 DB1 DB0 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 11 TRF3762 SLWS205A – JANUARY 2008 – REVISED MAY 2008 ....................................................................................................................................................... www.ti.com OUT_MODE<1,0>: TRF3762 has an optional divide by 2 or 4 output, which is selectable by programming bits <OUT_MODE_1, OUT_MODE_0> of register 1 (see Table 1). CP_TEST: By setting bit DB30 to 1 it is possible to test the PFD up or down pulses. Internal TI use only. TRIS_CP: If bit DB29 is set to 1, the charge pump output goes in tri-state. For normal operation, DB29 must be set to 0. ABPW: Bits <DB27, DB26> are used to program the width of the anti-backlash pulses of the PFD. The user selects one of the following values: 0.9ns, 1.5ns, 2.7ns and 3.8ns. Backlash can occur when Fpfd becomes phase aligned with Fout of the VCO. This will cause a high impedance state on the phase detector and allow the output frequency to drift until the phase difference is enough to cause the phase detector to start sending signals to the charge pump to correct the difference. This slight variation will show up as a sub harmonic of the pfd signal in the passband of the loop filter which would result in a significant spur in the output of the VCO. It is recommended that the anti-backlash pulse be set to the 1.5ns which gives the best spur reduction for the TRF3762. PFD_POL: Bit DB28 of register 1 sets the polarity of the PFD. A Low (0) selects a negative polarity, and a High (1) selects a positive polarity. By choosing the correct polarity, the TRF3762 will works with an external VCO having both positive and negative gain (Kv). For example if an external VCO has a Kv = -23MHz/V then the PFD polarity would need to be negative, so DB28 would be set to a Low (0). When using the internal VCO with a Kv of 23MHz/V, the PDF_POL should be set to 1. RDiv: A 14-bit word programs the RDiv for the reference signal, DB25 is the MSB and DB12 is the LSB. RDiv value is determined by dividing the reference frequency by the channel step size. For example if the reference frequency is 10MHz and the channel step size is 200KHz then RDiv would be 50. This sets up the Fpfd for the phase detector, in other words the reference frequency will be divided down by a factor of RDiv which in this example is 50. ICP: Bits <DB7, DB5> set the charge pump current. 1.2 V 22.168 ICP = × (N + 1) × Rbias1 8 (1) which reduces to: ICP = 3.3252 × (N + 1) Rbias1 (2) where N = decimal value of [Reg1 DB<7:5>]. The range is set by N and Rbias2. It is recommended that Icp be set to 7mA or <DB7, DB5>=101. OUTBUF_EN_SEL: Output buffer on/off state is controlled through serial interface or an external pin. If bit DB10 is a 0 (default state) the output buffers state is elected through bit DB11. If DB10 is a 1, the buffers on/off are directly controlled by the OUTBU_EN pin. RESET: Setting bit DB4 to 1, all registers are reset to default values. Refer to Register 1 under the Application Information section. Register Address DB0 DB1 DB2 Reference Frequency (Integer Part) DB3 DB4 DB5 DB6 Reference Frequency Continued DB16 DB17 DB7 DB8 Reference Frequency (Fractional Part) DB9 DB10 DB11 DB12 DB13 DB14 VCO Frequency in MHz DB18 DB19 DB20 DB21 DB22 DB23 DB24 DB25 DB15 START _CAL DB26 DB27 DB28 DB29 DB30 DB31 Figure 13. Register 2 12 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 TRF3762 www.ti.com ....................................................................................................................................................... SLWS205A – JANUARY 2008 – REVISED MAY 2008 Table 2. Register 2: VCO Calibration REGISTER 2 MAPPING Data Field Address Bits DB31 START_CAL DB30 FOUT12 DB29 FOUT11 DB28 FOUT10 DB27 FOUT9 DB26 FOUT8 DB25 FOUT7 DB24 FOUT6 DB23 FOUT5 DB22 FOUT4 DB21 FOUT3 DB20 FOUT2 DB19 FOUT1 DB18 FOUT0 DB17 REF_FRAC6 DB16 REF_FRAC5 DB15 REF_FRAC4 DB14 REF_FRAC3 DB13 REF_FRAC2 DB12 REF_FRAC1 DB11 REF_FRAC0 DB10 REF6 DB9 REF5 DB8 REF4 DB7 REF3 DB6 REF2 DB5 REF1 DB4 REF0 DB3 0 DB2 0 DB1 0 DB0 1 1 start calibration VCO frequency in MHz start calibration Reference frequency in MHz (fractional part) Reference frequency in MHz (integer part) 0000000 0000001 0000010 ..... 1100011 = 0.00MHz = 0.01MHz = 0.02MHz = 0.99MHz 0001010 = 10MHz 0001011 = 11MHz ..... 1101000 = 104MHz Address Bits <3,0>=0001 for register 2 Reference Frequency: The 14 bits <DB17, DB4> are used to specify the input reference frequency as multiples of 10kHz. Bits <DB10,DB4> specify the integer part of the reference frequency expressed in MHz. Bits <DB17,DB11> set the fraction part. Those values are then used during the calibration of the internal VCO. For example if using a 20MHz reference oscillator then bits<DB10,DB4> would be 0010100 and bits<DB17,DB11> would be 0000000. If the reference oscillator is 13.1MHz then bits<DB10,DB4> would be 0001101 and bits<DB17,DB11> would be 0001010. Start Calibration: A 1 in DB31 starts the internal VCO calibration. When the calibration is complete, DB31 bit is internally reset to 0. FOUT<12,0>: This 13-bit word <DB30,DB18> specifies the VCO output frequency in MHz. If output frequency is not a integer multiple of MHz, this value must be approximated to the closest integer in MHz. Refer to Register 2 under the Application Information section. Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 13 TRF3762 SLWS205A – JANUARY 2008 – REVISED MAY 2008 ....................................................................................................................................................... www.ti.com Register Address DB0 DB1 DB2 Dual-Modulus Prescalar Mode DB3 DB4 DB5 A-Counter DB6 DB7 DB8 DB9 B-Counter DB10 B-Counter DB16 DB17 DB18 DB19 DB20 DB11 DB12 Test MUX DB21 DB22 DB23 DB24 DB25 DB26 DB27 DB28 DB13 DB14 DB15 Lock PLL RSRV RSRV DB29 DB30 DB31 Figure 14. Register 3 Table 3. Register 3: A and B Counters REGISTER 3 MAPPING Data Field Address Bits 14 DB31 Rsrv Reserved DB30 Rsrv Reserved DB29 START_LK Lock PLL to frequency 1 active DB28 TEST_MUX_3 0001 = LOCK_DETECT enabled DB27 TEST_MUX_2 See Table 4 for descriptions and settings. DB26 TEST_MUX_1 DB25 TEST_MUX_0 DB24 B_12 DB23 B_11 DB22 B_10 DB21 B_9 DB20 B_8 DB19 B_7 DB18 B_6 DB17 B_5 DB16 B_4 DB15 B_3 DB14 B_2 DB13 B_1 DB12 B_0 DB11 A_5 DB10 A_4 DB9 A_3 DB8 A_2 DB7 A_1 DB6 A_0 DB5 PRESC_MOD1 DB4 PRESC_MOD0 DB3 0 DB2 0 DB1 1 DB0 0 13-bit B counter 6-bit A counter Dual-modulus prescaler mode <B5,B4>:00 <B5,B4>:01 <B5,B4>:10 <B5,B4>:11 Address Bits <3,0>=0010 for register 3 Submit Documentation Feedback for for for for 8/9 16/17 32/33 64/65 Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 TRF3762 www.ti.com ....................................................................................................................................................... SLWS205A – JANUARY 2008 – REVISED MAY 2008 B<12,0>: This 13-bit word <DB24,DB12> controls the value of the B counter of the N divider. The valid range is from 3 to 8191. A<5,0>: These 6 bits <DB11,DB6> control the value of the A counter. The valid range is from 0 to 63. PRESC_MOD<1,0>: These bits <DB5,DB4> define the mode of the dual-modulus prescaler according to Table 3. START_LK: TRF3762 does not load the serial interface registers values into the dividers registers until bit DB29 of register 3 is set to 1. After TRF3762 is locked to the new frequency, bit DB29 is internally reset to 0. Refer to Register 3 under the Application Information section. FUNCTIONAL DESCRIPTION VCO The TRF3762 integrates a high-performance, LC tank, voltage-controlled oscillator (VCO). For each of the devices of the TRF3762 family, the inductance and capacitance of the tank are optimized to yield the best phase-noise performance. The VCO output is fed externally and to the prescaler through a series of very low noise buffers, that greatly reduce the effect of load pulling onto the VCO. Divide by 2, by 4, and Output Buffer To extend the frequency coverage, the TRF3762 integrates a divide by 2 and by 4 with very low noise floor. The VCO signal is fed externally through a final open-collector differential-output buffer. This buffer is able to provide up to 3dBm (typical) of power into a 200Ω differential resistive load. The open-collector structure gives the flexibility to choose different load configurations to meet different requirements. N-Divider Prescaler Stage This stage divides down the VCO frequency before the A and B counters. This is a dual-modulus prescaler and the user can select any of the following settings: 8/9, 16/17, 32/33, and 64/65. Prescaling is used due to the fact that the internal devices are limited in frequency operations of 200MHz. To determine the proper prescaler value, Fout which is the frequency out of the VCO is divided by the numerator of the prescaler if the answer is less than 200MHz then that is the prescalar to use, see Equation 3. If the value is higher than 200MHz then repeat this procedure with the next prescalar numerator until a value of 200MHz or less is achieved. Refer to Synthesizing a Selected Frequency in the Section 7 Register 3. FOUT Prescalarnum £ 200MHz (3) A and B Counter Stage The TRF3762 includes a 6-bit A counter and a 13-bit B counter that operate on the output of the prescaler. The A counter can take values from 0 to 63, while the B counter can take values from 3 to 8191. Also, the value for the B counter must be greater than or equal to the value for the A counter. The A and B counter with the prescaler stage create the VCO N-divider, see Equation 4 and Equation 5. Refer to Synthesizing a Selected Frequency in the Section 7 Register 3. Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 15 TRF3762 SLWS205A – JANUARY 2008 – REVISED MAY 2008 ....................................................................................................................................................... www.ti.com N= FOUT = (A COUNTER + Prescalarnum × B COUNTER ) FPFD (4) N = xinteger ´ y decimal , Þ Prescalarnum BCOUNTER = xinteger and A COUNTER = Prescalarnum × y decimal (5) Reference Divider TRF3762 includes a 14-bit RDiv, also known as RDiv, that allows the input reference frequency to be divided down to produce the reference clock to the phase frequency detector (PFD) this clock is also known as FPFD which is also the channel step size. Division ratios from 1 to 16,383 are allowed. To determine RDIV use Equation 6. RDIV = FREF_IN FPFD (6) The output frequency (FOUT) is determined using Equation 7. FOUT = FPFD × N = FREF_IN RDIV × (A COUNTER + Prescalarnum × B COUNTER ) (7) Phase Frequency Detector (PFD) and Charge Pump Stage The outputs of the RDiv and the N counter are fed into the PFD stage, where the two signals are compared in frequency and phase. The TRF3762 features an anti-backlash pulse, whose width is controllable by the user through the serial programming interface. The PFD feeds the charge pump, whose output current pulses are fed into an external loop filter, which eventually produces the tuning voltage needed to control the integrated VCO to the desired frequency. Mux Out MUX_OUT pin (39) provides a communication port to the microcontroller circuit. See Table 4 in the Application Information section. Div 1/2/4 Div 1/2/4 is the frequency divider for the TRF3762. This circuit can be programmed thru the serial programming interface (SPI) to divide the output frequency of the VCO by 1, 2 or 4. This feature allows for the same loop filter design to be used for any of the 3 divide by modes, 1, 2 and 4. For example, if the VCO is running at 1499MHz to 1608MHz band then with the same exact circuit, run the output in the divide by 2 mode 749.5MHz to 804MHz band or in the divide by 4 mode 374.75MHz to 402MHz. Serial interface The programming interface pins (3, 4, 5) to the chip are the serial programming interface (SPI). The interface requires a Clock, Data, and Strobe signal to operate. See timing diagram Figure 11. CHIP ENABLE This feature provides a way to shut down the chip when not needed in order to conserve power. CHIP_EN Pin (2) needs to be High for normal operation. Buffer Power Down PD_OUTBUFF pin (1), when enabled in software can provide a -40dB reduction in the output power while the VCO is locked and running. This feature is to help with isolation between RX and TX. 16 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 TRF3762 www.ti.com ....................................................................................................................................................... SLWS205A – JANUARY 2008 – REVISED MAY 2008 APPLICATION INFORMATION Initial Calibration and Frequency Setup at Power Up The integrated high performance VCO requires an internal frequency calibration at power up. To perform such calibration the following procedure is recommended: • Apply 5V power supply to IC. • Apply an input reference frequency to pin (38) and ensure the signal is stable. • Turn on the TRF3762 using the chip enable pin (CHIP_EN, pin 2), by applying 5V. Register 1 • Setup the device through Register 1 referencing Table 1. a. The first 4 bits of the 32-bit code sent to the chip are set DB <3:0> to 0000; which is the address of register 1. b. Bit 5, DB4, sets the soft reset for the chip. Soft reset allows for the registers to be reset without powering down the chip. If a soft reset is used then write to register 1 twice: once with DB4 set high and once with DB4 set low. Typically, this bit is only used when the chip has been powered up and registers 1, 2, and 3 have already been written to, so on power-up reset is not required, so DB4 is, by default, set low. c. DB <7: 5> sets the charge pump current based on the resistor value on pin 28 of the TRF3762 and the decimal value of Register 1, DB<7:5> used in Equation 1. This equation reduces to Equation 2, where N = decimal value of [Reg1 DB<7:5>]. d. DB <9: 8> sets the mode of the chip. The mode is how the device will or will not divide down the VCO’s frequency. There are 3 choices for the mode setting, divide by 1, 2 or 4 per Table 1. For example if 525MHz is required from the TRF3762 which has a main frequency of 1575MHz then the divide-by-4 mode is chosen by setting DB <9: 8> to 10. e. DB <11:10> controls the output buffer. Both of these are set to 00 by default, so the buffer is controlled internally. See Table 1 for more information. f. DB <25:12> sets the RDiv value. Once the calculations under the Synthesizing a Selected Frequency section have been completed the value is known, based on the external reference oscillator. The value for R is entered into the DB <25:12>. For example, if the reference oscillator is at a frequency (FREF_IN) of 61.44MHz and a channel step size of 120kHz is required, which is also the frequency (FPFD) the phase frequency detector will use to compare against the VCO's output frequency (FOUT), then FREF_IN /FPFD = 512, which is entered as follows: MSB: LSB 0001000000000. g. By default, DB <27:26> are set to 00 for a 1.5ns delay on the anti-backlash pulse width. See Table 1 for more information. h. DB 28 is set to 1 for positive by default. See Table 1 for more information. i. DB 29 is set to 0 for normal operation. See Table 1 for more information. j. DB 30 is set to 0 by default. See Table 1 for more information. k. DB 31 is set to 0 by default. See Table 1 for more information. Register 2 • Initiate calibration procedure by programming register 2 as follows: Reference Table 2 a. The first 4 bits of the 32-bit code sent to the chip are set DB <3:0> to 0001; which is the address of register 2. b. Use bits DB<17, 4> of register 2 to specify the input reference frequency in MHz. The value is split into an integer and a fraction part. For example: to insert a fREF of 30.72MHz, set: – DB<10, 4> (integer part) equal to 0011110 (30) and – DB<17, 11> (fraction part) equal to 1001000 (72). Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 17 TRF3762 SLWS205A – JANUARY 2008 – REVISED MAY 2008 ....................................................................................................................................................... www.ti.com • c. Set DB<30:18> of register 2 to the desired frequency. For example: 2200MHz would be 0100010011000 (2200). d. Set DB31of register 2 to 1 to start the calibration. The VCO calibration runs for 5ms. During the cal procedure it will not be possible to program register 2 and 3. At the end of the calibration, bit DB31 of register 2 resets to 0. e. Subsequent frequency programming requires DB31 to be set to 0. Register 3 Completion of the frequency set up, on initial calibration, cannot proceed until 5ms has elapsed, due to full calibration, then it will require that the A and B values, the prescalar ratio, be known. See Synthesizing a Selected Frequency section below for calculation. Reference Table 3. a. The first 4 bits of the 32-bit code sent to the chip are set DB <3:0> to 0010; which is the address of register 3. b. DB<5:4> sets the prescalar ratio, 8/9, 16/17, 32/33, 64/65. For example: if 16/17 are required, set the register bits DB<5:4> to 01. c. DB<11:6> sets the A value for the N counter. For example: if A is 4, set DB<11:6> as follows: 000100 (4). d. DB<24:12> sets the B value for the N counter. For example: if B is 1156, set DB<24:12> as follows: 0010010000100 (4). e. DB<28:25> sets the TEST_MUX. This allows the user to check via the microcontroller the state of the TRF3762 by programming it to one of 6 states. The most common state to use is the Digital lock Detect which places the pin in a logic high state with indicates the VCO is locked. Table 4. MUX-Out Settings STATE DB<28:25> STATE DB<28:25> 3-state o/p ( High impedance state on Pin 39) 0000 RDiv o/p (Shows R-value on Pin 39) 0100 Digital lock Detect (High when locked on Pin 39) 0001 Analog lock detect (High when locked on Pin 39) 0101 N-Divider o/p (Shows N-value on Pin 39) 0010 Read back ( read back register settings) 0110 DVDD (internal TI use) 0011 DGND (internal TI use) 0111 f. DB29 sets the START LOCK, which is set to 0, on the initial frequency setup and then set to 1 on additional frequency changes. Once all registers are written, the TRF3762 will lock to the desired frequency. In order to change the frequency once the initial calibration is complete, only registers 2 and 3 need to be reprogrammed. No calibration is required. Re-Calibration After Power Up Assuming the TRF3762 is powered up and operational, a VCO calibration is also possible without powering down the IC. To perform such calibration the following procedure is recommended: • Set bit DB4 (RESET) of register 1 to 1. This performs a software reset and clears all registers of VCO calibration data. Once the reset command is issued then DB4 of register 1 will need to be set to 0. • Repeat the Initial Calibration and Frequency setup at Power up section, skipping the power up section and performing the register programming sequence. 18 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 TRF3762 www.ti.com ....................................................................................................................................................... SLWS205A – JANUARY 2008 – REVISED MAY 2008 Synthesizing a Selected Frequency The TRF3762 is an integer-N PLL synthesizer, and because of its flexibility (14-bit RDiv, 6-bit A counter, 13-bit B counter, and dual modulus prescaler), is ideal for synthesizing virtually any desired frequency. If synthesizing a 900MHz local oscillator, with spacing capability (minimum frequency increment) of 200kHz, as in a typical GSM application, the choice of the external reference oscillator is beyond the scope of this section. However, if a 10MHz reference is selected, the settings are calculated to yield the desired output frequency and channel spacing. There is more than one solution to a specific set of conditions, so below is one way of achieving the desired result. First, select the appropriate RDiv counter value. Since a channel spacing of 200kHz is desired, the FPFD is set to 200kHz. Calculate the RDiv value through: RDiv = FREFIN/FPFD = 10MHz/ 200kHz = 50. Assume a prescaler value of 16/17 is selected. This is a valid choice, since the prescaler output is well within the 200MHz limit (1805MHz / 16 = 112.8MHz). Select the appropriate A and B counter values. RFOUT = FPFD × N = (FREFIN / RDiv) × (A counter + Prescalar numerator × B counter). Therefore, the following equation must be solved: 1805MHz = 200kHz x (A + 8 × B). There are many solutions to this single equation with two unknowns; there are some basic constraints on the solution, since 3 ≤ B ≤ 8191, and also B ≥ A. So, if A = 1, solving the equation yields B = 564. One complete solution would be to choose: RDiv = 50, A counter = 1, Bcounter = 564 and Prescalar = 16/17 resulting in the desired N counter value = 9025. This is how the A counter, B counter and prescalar make up the N counter. When this procedure is complete the values for the N counter , R, and the prescalar ratio should be known. Registers 2 and 3 need to be set up for operation of the chip. See Table 2 and Table 3 for this procedure. Register 2 bits <DB30:DB18> 12:0 set the output frequency of the device along with register 3. See the N-Divider section under the Functional Description. Application Schematic Figure 15 shows a typical application schematic for the TRF3762. In this example, the output signal is taken differential using the 2 resistive pull-up resistors of the final output buffer. A single-ended and tuned load configuration is also available. The loop filter components: C1 = 680pF, R1 = 7.5kΩ, C2 = 10,000pF, R2 = 6.34kΩ, C3 = 330pF are typical ones used for the plots shown above. Those values can be optimized differently according to the requirements of the different applications. Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 19 TRF3762 REF C1 C4 1000 pF AVDD_REF AVDD_CP CPOUT GND AVDD 37 36 35 34 33 32 31 30 GND GND C2 39 38 MUX_OUT (See Note A) C3 R1 REF_IN 40 1 PD_OUTBUF R2 GND R3 2.37 kΩ CHIP_EN 2 29 AVDD_BIAS CLOCK 3 28 RBIAS1 DATA 4 27 GND STROBE 5 26 VCTRL_IN DGND 6 25 AVDD_VCO DGND 7 24 AVDD_BUF DVDD1 8 23 AVDD_CAPARRAY AVDD_PRES 9 22 GND R5 120 Ω RSVD 21 19 20 C7 1000 pF R6 120 Ω AVDD GND 18 RBIAS2 16 17 AVDD_VCOBUF 15 GND 14 AVDD_OUTBUF 12 13 VCO_OUTM GND 10 11 VCO_OUTP GND TRF3762 (TOP VIEW) GND To Microcontroller DVDD2 To Microcontroller SLWS205A – JANUARY 2008 – REVISED MAY 2008 ....................................................................................................................................................... www.ti.com R4 4.75 kΩ VDD VDD C5 10 pF C6 10 pF LOAD A. Refer to the Application Information section Loop Filter Design. Figure 15. TRF3762 Application Schematic 20 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 TRF3762 www.ti.com ....................................................................................................................................................... SLWS205A – JANUARY 2008 – REVISED MAY 2008 Loop Filter Design Numerous methodologies and design techniques exist for designing optimized loop filters for particular applications. The loop filter design can affect the stability of the loop, the lock time, the bandwidth, the extra attenuation on the reference spurs, etc. The role of the loop filter is to integrate and lowpass the pulses of the charge pump and eventually yield an output tuning voltage that drives the VCO. Several filter topologies can be implemented, including both passive and active. In this section, a third-order passive filter is used. For this example, assume these several design parameters. The internal VCO has a value of 23MHz/V, meaning that in the linear region, changing the tuning voltage of the VCO by 1V induces a change of the output frequency of about 23MHz. It is known that N = 4500 and Fpfd = 200kHz from our previous example. It is assumed that current setting in register 1 <DB7:DB5> is set to 100 and sets a maximum current of 5.6mA. TI recommends an Icp of 5.6mA, which give the best spur performance, but can be changed for different application. In addition, the bandwidth of the loop filter must be determined. This is a critical consideration as it affects the lock time of the system. Assuming an approximate bandwidth of around 20kHz is required and that for stability a phase margin of about 45 degrees is desired, the following values for the components of the loop filter can be derived. There is almost an infinite number of solutions to the problem of designing the loop filter and the designer is called to make tradeoff decisions for each application. Texas Instruments has provided a loopfilter program in the product folder for the TRF3762. Some terms are interchangeable and are described and equated here: • Fcom = FPDF which identify the comparing frequency or phase detector frequency which is also equal to the system channel step size. FOUT must be a multiple of Fcom. • Fmin is the lower frequency of the design band. • Fmax is the upper frequency of the design band. • Fref is the reference frequency for the PLL. Fref must be a multiple of Fcom. • Kvco = Kv expressed in MHz per Volt (MHz/V) which is the gain of the VCO. The TRF3762 internal VCO has a Kv = 23MHz/V. • Icp is the charge pump current. The TRF3762 is typically set to 5.6mA. • Fc is the loop filter bandwidth which should be no more than 1/10 Fcom. • φ is phase margin in degrees. Values should be between 30 and 70. The higher the phase margin the better the stability of the PLL but the slower the lock time. 45 degrees is a good tradeoff. • T3/T1 in percent is the percentage of the poles in the loop filter. Usually set to 45%. The higher the value (closer to 100%) the more the spurs are attenuated, but peaking occurs in the pass band of the loop filter. Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 21 TRF3762 SLWS205A – JANUARY 2008 – REVISED MAY 2008 ....................................................................................................................................................... www.ti.com FOUT = FminFmax (8) FOUT F com vc = 2πFc (10) æ 1 ö ç ÷ - tanf cosf ø è T1 = T3 ö æ vc ç 1 + T1 ÷ø è (11) æ T3 ö T3 = ç ÷ T1 è T1 ø (12) N= T2 = (9) 1 vc2 (T1+T3 ) é K Kf ê T1 C1 = × VCO x ê ê T2 vc2N ê ë (13) 1 ù2 2 ú 1 + (vc T2 ) ú ú 2 2 2 2 1 + vc T1 1 + vc T3 ú û ( )( ) (14) C1 æ T2 ö C2 = C1ç - 1÷ , C3 = T1 10 è ø (15) T2 T3 R1 = , R2 = C2 C3 (16) Loop filter components: C1 = 303pF R1 = 8.87kW R2 = 3.4kW C2 = 1650pF C3 = 330pF Frequency jump from 1046MHz to 1085MHz: Locktime freq ~ 250mS Figure 16. Phase Locktime 22 Figure 17. Frequency Locktime Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 TRF3762 www.ti.com ....................................................................................................................................................... SLWS205A – JANUARY 2008 – REVISED MAY 2008 Loop Filter Design Example Given these parameters which were used for the lock time plot Figure 17: • Fmin = 1805 MHz • Fmax = 1936 MHz • Fcom = 200 KHz • Icp = 7mA • Kvco = 23 MHz • Fc = 40 KHz • Phase Margin = 35 degrees • T3/T1 = 35% Calculate FOUT of design FOUT = FminFmax = 1870MHz (rounded up) (17) Next calculate N N= FOUT = 9350 F com (18) Then calculate ωc vc = 2πFc = 251.3 x 103 (19) Now calculate T1-T3 to give the RC time constants. æ 1 ö ç ÷ - tanf cosf ø T1 = è = 1.5 x 10-6 T3 ö æ vc ç 1 + T1 ÷ø è (20) Use T1 to find T3 æT ö T3 = ç 3 ÷ T1 = 537 x 10 -9 T1 ø è (21) Then use T1 and T3 to find T2 T2 = 1 = 7.6 x 10 -6 2 v (T1 + T3 ) C (22) Now C1, C2, C3, R1, and R2 are calculated using T1, T2, and T3. 1 é ù2 2 ê ú 1 + (vc T2 ) K Kf T ú = 110pF C1 = 1 × VCO × ê 2 ê ú T2 2 2 2 2 vc N 1 + vc T ú ê 1 + vc T1 3 ë û ( )( ) (23) æT ö C2 = C1ç 2 - 1÷ = 436pF è T1 ø C1 C3 = = 11pF 10 (24) (25) Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 23 TRF3762 SLWS205A – JANUARY 2008 – REVISED MAY 2008 ....................................................................................................................................................... www.ti.com Now using C2 and T2, find R2. Use C3 and T3 to find R3 T R2 = 2 = 17kΩ C2 T R3 = 3 = 49kΩ C3 (26) (27) R3 x C3 can be scaled using T3, so if C3 = 110pF, then R3 = 41 kΩ => 4.9 kΩ in the loop filter. R2 and C2 can be adjusted to improve the lock time. The actual values used in the lock time plot were optimized for lock time as well as using real valued components. Layout/PCB Considerations This section of the design of the complete PLL is of paramount importance in achieving the desired performance. Wherever possible, a multi-layer PCB board should be used, with at least one dedicated ground plane. A dedicated power plane (split between the supplies if necessary) is also recommended. The impedance of all RF traces (the VCO output and feedback into the PLL) should be controlled to 50Ω. All small value (10pF and 0.1µF) decoupling capacitors should be placed as close to the device pins as possible. It is also recommended that both top and bottom layers of the circuit board be flooded with ground, with plenty of ground vias dispersed as appropriate. Because the digital lines are not in use during normal operation of the device and are only used to program the device on start up and during frequency changes the analog grounds (GND) and digital grounds (DGND) are tied to the same ground plain. The most sensitive part of any PLL is the section between the charge pump output and the input to the VCO. This includes the loop filter components, and the corresponding traces. The charge pump is a precision element of the PLL and any extra leakage on its path can adversely affect performance. Extra care should be given to ensure that parasitics are minimized in the charge pump output, and that the trace runs are short and optimized. Similarly, it is also recommend that extra care is taken in ensuring that any flux residue is thoroughly cleaned and moisture baked out of the PCB. From an EMI perspective, and since the synthesizer is typically a small portion of a bigger, complex circuit board, shielding is recommended to minimize EMI effects. 24 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 TRF3762 www.ti.com ....................................................................................................................................................... SLWS205A – JANUARY 2008 – REVISED MAY 2008 MUX_OUT Via to bottom ground BOTTOM GND TOP GND De-coupling Capacitor’s on back side of board RSVD De-coupling Capacitor’s on top side of board BOTTOM GND A. See the Application Information section for Loop Filter Design procedures. Figure 18. TRF3762 Layout Application Example for a High Performance RF Transmit Signal Chain Much in the same way as described above, the TRF3762 is an ideal synthesizer to use in implementing a complete high performance RF transmitter chain such as the TSW3000 and TSW3003 Demonstration kits. Using a complete suite of high performance Texas Instruments components, a state-of-the-art transmitter can be implemented featuring excellent performance. Texas Instruments offers ideal solutions for the digital-to-analog conversion portion of transmitter as well as the analog and RF components needed to complete the transmitter. The baseband digital data is converted to I and Q signals through the dual DAC5687, which features a 16-bit interpolating dual digital-to-analog converter (DAC). The device incorporates a digital modulator, independent differential offset control, and I/Q amplitude control. The device is typically used in baseband mode or in low IF mode in conjunction with an analog quadrature modulator. The DAC5687, after filtering, feeds a TRF3703, which is a direct, upconversion IQ modulator. This device accepts a differential input voltage quadrature signal at baseband or low IF frequencies and outputs a modulated RF signal based on the LO drive frequency. The LO Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 25 TRF3762 SLWS205A – JANUARY 2008 – REVISED MAY 2008 ....................................................................................................................................................... www.ti.com drive input of the IQ modulator is generated by the TRF3762. The TRF3762 is a family of high performance, highly integrated frequency synthesizers, optimized for wireless infrastructure applications. The TRF3762 includes an integrated VCO and integer-N PLL. Different members of the TRF3762 family can be chosen for application specific VCO frequency ranges. In addition, the CDC7005 clocking solution can be used to clock the DAC and other portions of the transmitter. A block diagram of the proposed architecture is shown in Figure 19. For more details, contact Texas Instruments directly. Digital-to-RF Up Converter Gain and Power Amplifier DAC TX LPA ANT 0° 90° I/Q Modulator Diplexer I/Q Demod A/D RX LNA LO-to-Digital Conveter Low Noise Amplifier and RF-to-LO Down Converter Figure 19. Transmit Chain Block Diagram 26 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): TRF3762 PACKAGE OPTION ADDENDUM www.ti.com 4-Sep-2008 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty TRF3762-EIRHAR ACTIVE QFN RHA 40 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-3-260C-168 HR TRF3762-EIRHAT ACTIVE QFN RHA 40 250 CU NIPDAU Level-3-260C-168 HR Green (RoHS & no Sb/Br) Lead/Ball Finish MSL Peak Temp (3) (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. 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Addendum-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 3-Sep-2008 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel Diameter Width (mm) W1 (mm) A0 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant TRF3762-EIRHAR QFN RHA 40 2500 330.0 16.4 6.3 6.3 1.5 12.0 16.0 Q2 TRF3762-EIRHAT QFN RHA 40 250 330.0 16.4 6.3 6.3 1.5 12.0 16.0 Q2 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 3-Sep-2008 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) TRF3762-EIRHAR QFN RHA 40 2500 333.2 345.9 28.6 TRF3762-EIRHAT QFN RHA 40 250 333.2 345.9 28.6 Pack Materials-Page 2 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. 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