19-3425; Rev 0; 10/04 KIT ATION EVALU LE B A IL A AV Single-Chip Global Positioning System Receiver Front-End The MAX2745 complete single-chip global positioning system (GPS) RF front-end downconverter utilizes many innovative and leading-edge RF CMOS design techniques. This high-performance, state-of-the-art device consumes extremely low power and eliminates the need for costly SAW and bulky discrete IF filters. The MAX2745 incorporates a fully integrated low-noise amplifier (LNA) and mixer, IF section, digital sampler, and local oscillator synthesizer. The MAX2745 also provides a voltage supply for an external LNA. In addition, the MAX2745 features a voltage booster, which can extend the power-supply voltage to as low as 1.6V. The MAX2745 supports both 3rd overtone crystal designs in 32MHz and fundamental frequency crystal designs in 16MHz, as well as a TCXO implementation. In addition, the MAX2745 incorporates an on-chip temperature sensor and crystal oscillator with trimmed capacitors, resulting in a very accurate frequency and additional system cost savings. The MAX2745 is available in a space-saving 48-pin TQFP package and is specified for the extended (-40°C to +85°C) temperature range. The power consumption of this device is as low as 41mW at 2.4V. Features ♦ Complete Single-Chip GPS Radio for 16.368MHz and 32.736MHz Floorplans ♦ Single-Ended or Differential Outputs at 4.092MHz ♦ Low 3.5dB Typical Noise Figure ♦ No External IF SAW or Discrete Filters Required ♦ On-Chip Temperature Sensor ♦ 2.4V to 3.6V Operational Supply Voltage Range ♦ Power Consumption as Low as 41mW at 2.4V ♦ Wide -40°C to +85°C Operational Temperature Range Ordering Information PART MAX2745ECM TEMP RANGE PIN-PACKAGE -40°C to +85°C 48 TQFP-EP* *EP = Exposed paddle. Typical Operating Circuit appears at end of data sheet Applications Block Diagram/ Pin Configuration Recreational Handheld/Walkie Talkies SHDN GND VDD CP_OUT GND VTUNE VDD VTO SDATA 48 47 46 45 44 43 42 41 40 39 38 37 36 BPF_CTRL RBIAS 1 VCXO CBIAS 2 Geographical Information Systems (GISs) VDD 3 Emergency Roadside Assistance VDD 4 Emergency Response Systems GND 5 Digital Cameras/Camcorders GND 6 Consumer Electronics VDD Telematics (Vehicle/Asset Tracking and Inventory Management) XTALOUT Location-Based Services (PDAs and Accessories) XTALIN In-Vehicle Navigation Systems (IVNSs) TEMPERATURE SENSOR MAX2745 35 ODS 34 CFS BIAS PFD 33 COE CHG PUMP DIVIDER 32 VDD 31 SCLK VSPORT LNA/MIXER VCO RFIN 7 30 GND 29 VOUT+ GND 8 VDD 9 28 VOUTBANDPASS FILTER QUANTIZER AGC 27 VDD IEXT_LNA 10 VDD 11 VOLTAGE BOOSTER FILTER AUTOMATIC TUNING 26 GND AGC_FIL 12 14 15 16 17 18 19 20 21 22 23 24 VDD GND XTAL_SSEL XTAL_CSEL BST_CTRL TEST_EN VDD_VB CKOUT DOUT VB_CS+ VB_CS- VOUT 25 VDD 13 ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX2745 General Description MAX2745 Single-Chip Global Positioning System Receiver Front-End ABSOLUTE MAXIMUM RATINGS VDD to GND ...........................................................-0.3V to +3.7V Other Pins to GND......................................-0.3V to (VDD + 0.3V) RF LNA Input Power .......................................................+10dBm Continuous Power Dissipation (TA = +70°C) 48-Pin TQFP-EP (derate 12.5mW/°C above +70°C) ............1W Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Soldering Temperature (10s) ...........................................+300°C CAUTION! ESD SENSITIVE DEVICE 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 in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. DC ELECTRICAL CHARACTERISTICS (MAX2745 EV kit, VDD = +2.4V to +3.6V, SHDN = GND, TA = -40°C to +85°C. Typical values are at VDD = +3.0V and TA = +25°C, unless otherwise noted.) PARAMETER CONDITIONS Supply Voltage Supply Current Optional External LNA Supply Current MIN TYP 2.4 VDD = +3.0V, TA = +25°C (Note 1) 20.5 Shutdown mode MAX UNITS 3.6 V 27 mA 11 VDD = +3.0V µA 10 Logic-Input High Voltage 2.0 V Logic-Input Low Voltage Logic-Input Bias Current mA -10 0.5 V +10 µA AC ELECTRICAL CHARACTERISTICS (MAX2745 EV kit, VDD = +2.4V to +3.6V, SHDN = GND, TA = -40°C to +85°C. Typical values are at VDD = +3.0V and TA = +25°C, unless otherwise noted.) PARAMETER GENERAL PERFORMANCE Maximum Conversion Gain Input Frequency Noise Figure Return Loss (S11) LNA/Mixer Input IP3 Output IF Frequency OUTPUT STAGE Output Rise/Fall Time Output-Voltage-Level Low Output-Voltage-Level High 2 CONDITIONS (Notes 2, 3) Measured at quantizer output f1 = 5.09MHz and f2 = 7.09MHz above carrier frequency Differential (VOUT+, VOUT-), CL < 20pF Single ended (DOUT), CL<20pF Differential Single ended Differential Single ended MIN TYP MAX UNITS 105 1575.42 3.5 -14 -25 4.092 120 dB MHz dB dB dBm MHz 16 6 VDD - 0.9 0 VDD _______________________________________________________________________________________ ns V V Single-Chip Global Positioning System Receiver Front-End (MAX2745 EV kit, VDD = +2.4V to +3.6V, SHDN = GND, TA = -40°C to +85°C. Typical values are at VDD = +3.0V and TA = +25°C, unless otherwise noted.) PARAMETER SYNTHESIZER CONDITIONS MIN TYP Fundamental frequency crystal 3rd overtone crystal Crystal Input Frequency 16.368 32.736 0.4 Charge-Pump Current fOFFSET = 10kHz offset, BWLOOP = 70kHz fOFFSET = 1MHz offset, BWLOOP = 70kHz BWLOOP = 70kHz (Notes 2, 3) (Notes 2, 3) Phase Noise Maximum PLL Spur VCO Tuning Frequency Range VCO Tuning Gain IF STAGE IF Stage Gain Dynamic Range IF Stage Gain Bandpass Filter 1dB Corner Frequency Bandpass Filter 3dB Bandwidth Bandpass Filter 60dB High-Side Rejection Bandpass Filter 60dB Low-Side Rejection Image Rejection In-Band Ripple AGC Loop Lock Time MAX UNITS MHz mA -81 dBc/Hz -104 -39 210 210 150 150 VGA set at maximum gain 270 310 80 56 3.1 5.1 2.0 Low-frequency corner High-frequency corner dBc MHz MHz/V dB dB MHz MHz 6.6 MHz 1.6 MHz 17 1 1 dB dB ms Note 1: At TA = +25°C, min/max limits are guaranteed by production test. Note 2: At TA = -40°C, min/max limits are guaranteed by design and characterization. Note 3: At TA = +25°C and +85°C, min/max limits are guaranteed by production test. Typical Operating Characteristics (MAX2745 EV kit, VDD = +3.0V, SHDN = GND, fRF = 1575.42MHz, and TA = +25°C, unless otherwise noted.) VCC = 2.7V VCC = 3V 18 VCC = 2.4V 14 VCC = 3V 90 25 20 15 VCC = 2.4V 10 VCC = 2.7V -20 0 20 40 TEMPERATURE (°C) 60 80 80 75 VCC = 3V VCC = 2.7V 65 0 -40 VCC = 2.4V 85 70 5 10 95 IF STAGE GAIN (dB) LNA MIXER GAIN (dB) 22 35 30 IF STAGE GAIN vs. TEMPERATURE 100 MAX2745 toc02 MAX2745 toc01 26 SUPPLY CURRENT (mA) LNA/MIXER GAIN vs. TEMPERATURE 40 MAX2745 toc03 SUPPLY CURRENT vs. TEMPERATURE 30 60 -40 -20 0 20 40 TEMPERATURE (°C) 60 80 -40 -20 0 20 40 60 80 TEMPERATURE (°C) _______________________________________________________________________________________ 3 MAX2745 AC ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (MAX2745 EV kit, VDD = +3.0V, SHDN = GND, fRF = 1575.42MHz, and TA = +25°C, unless otherwise noted.) 106 VCC = 2.4V 104 102 100 -40 -20 0 20 40 60 80 1.4 1.2 1.0 VDD = 3.6V 0.8 0.6 0.4 VDD = 2.4V 0.2 0 3.2 VOLTAGE-BOOSTER OUTPUT, VOUT (V) VCC = 2.7V 108 1.6 MAX4725 toc05 VCC = 3V TEMPERATURE-SENSOR OUTPUT VOLTAGE, VTO (V) MAX2745 toc04 110 VOLTAGE-BOOSTER OUTPUT vs. VDD_VB MAX2745 toc06 TEMPERATURE-SENSOR OUTPUT VOLTAGE vs. TEMPERATURE TOTAL GAIN vs. TEMPERATURE TOTAL GAIN (dB) MAX2745 Single-Chip Global Positioning System Receiver Front-End BST_CTRL = HIGH VOUT = VDD 3.0 TA = -40°C 2.8 2.6 TA = +25°C 2.4 TA = +85°C 2.2 2.0 -40 -20 0 20 40 60 80 TEMPERATURE (°C) TEMPERATURE (°C) 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 VDD_VB (V) Pin Description PIN NAME 1 RBIAS External BIAS Resistor. For normal bias, connect a 100kΩ (1%) resistor to ground. FUNCTION BIAS Bypass Capacitor. Connect a 0.1µF capacitor to ground. 2 CBIAS 3, 4, 9, 11, 13, 25, 27, 32, 39, 43, 46 VDD Power-Supply Voltage. Bypass with a 0.1µF capacitor to ground as close to the pins as possible. 5, 6, 8, 14, 26, 30, 41, 44 GND Ground 4 7 RFIN 10 IEXT_LNA External LNA Voltage Supply RF Input Signal. Requires external matching network. 12 AGC_FIL AGC External Filter. Requires external RC lowpass filter. 15 XTAL_SSEL Crystal Swing Select. Drive logic high for full swing. Drive logic low for limited swing. 16 XTAL_CSEL Crystal Clock Select. Drive logic high for fundamental mode of 16.368MHz. Drive logic low for third overtone mode of 32.736MHz. 17 BST_CTRL Active-High Boost Control Input. Drive logic high to activate the voltage booster (crystal oscillator is biased from BIAS). Drive logic low to deactivate the voltage booster (crystal oscillator is self-biased). 18 TEST_EN 19 VDD_VB Power Supply for Voltage Booster. Connect to VDD if voltage booster is not used. 20 CKOUT Full-Swing Clock Output 21 DOUT 22 VB_CS+ Positive Voltage Booster External Floating CAP. Connect a 6nF capacitor to GND. 23 VB_CS- Negative Voltage Booster External Floating CAP. Connect a 6nF capacitor to GND. 24 VOUT Connect to Ground for Normal Operation Single-Ended Full-Swing Digital Output Voltage Booster Output. Bypass to GND with a 1µF capacitor as close to the pin as possible. _______________________________________________________________________________________ Single-Chip Global Positioning System Receiver Front-End PIN NAME FUNCTION 28 VOUT- Quantizer Analog Negative Limited-Swing Output 29 VOUT+ Quantizer Analog Positive Limited-Swing Output 31 SCLK Serial Port Clock Input (Bidirectional PAD) 33 COE Clock Output Enable. Drive logic high to enable the clock output. Drive logic low to disable the clock output. 34 CFS Clock Frequency Select. Drive logic high to select 16MHz. Drive logic low to select 32MHz. 35 ODS Output Data Select. Drive logic high to select full-swing output. Drive logic low to select limitedswing output. 36 BPF_CTRL 37 SDATA 38 TEMPOUT 40 VTUNE 42 CP_OUT 45 SHDN 47 XTALOUT 48 XTALIN Bandpass Filter (BPF) Control. Drive logic high to activate the tuning block control BPF. Drive logic low to let BPF be controlled by fuses. Serial Port Data (Bidirectional PAD) Temperature Sense DC Voltage Output VCO Tuning Input PLL Charge-Pump Output. Analog high-impedance output. Current source. Connect directly to the PLL loop filter input. Active-High Shutdown Input. Drive logic low to disable all device functions. Drive logic high for normal operation. Crystal Output. Connect directly to the external crystal. Crystal Input. Connect directly to the external crystal or TCXO. Functional Diagram 4.092MHz IF OUTPUT: 1.57542GHz BPF IMAGE REJECTION BPF LNA VGA QUANTIZER AGC SHUTDOWN VDD1V6 OUTPUT CONTROL POWER SWITCH /96 /48 VOLTAGE BOOSTER FULL SWING DIFFERENTIAL LIMITED SWING PFD 16.368MHz 32.768MHz MAX2745 DIGITAL CONTROL TEMP SENSOR VSPORT TEMP SENSOR DC OUTPUT CP PLL LOOP FILTER CLOCK OUTPUT: 16.368MHz 32.768MHz MUX CLOCK FREQ CONTROL CLOCK OUTPUT CONTROL _______________________________________________________________________________________ 5 MAX2745 Pin Description (continued) MAX2745 Single-Chip Global Positioning System Receiver Front-End Detailed Description The MAX2745 complete single-chip GPS front-end downconverter utilizes many innovative and leadingedge RF CMOS design techniques. This high-performance, state-of-the-art device consumes extremely low power and eliminates the need for costly SAW and bulky discrete IF filters. The MAX2745 incorporates a fully integrated LNA/mixer, IF section, digital sampler, and local oscillator synthesizer. The MAX2745 also provides voltage supply for an external LNA. In addition, the MAX2745 features a voltage booster that can extend the power-supply voltage to as low as 1.6V. The MAX2745 supports both 3rd overtone crystal designs in 32MHz and fundamental frequency crystal design in 16MHz, as well as a TCXO implementation. In addition, the MAX2745 incorporates an on-chip temperature sensor and crystal oscillator with trimmed capacitors, resulting in a very accurate frequency and additional system cost savings. The MAX2745 also incorporates a 2MHz bandwidth bandpass filter to reduce off-band noise. The bandwidth and the center frequency of the bandpass filter are guaranteed by an advanced tuning scheme. The MAX2745 is offered in a space-saving 48-pin TQFP package. The operational temperature range is specified from -40°C to +85°C. The power consumption of this device is as low as 41mW at 2.4V. LNA/Mixer The RF input signal from the GPS antenna is fed through an LNA with a gain of 20dB. The amplified signal is then fed to a mixer that downconverts the signal (1575.42MHz) to a quadrature differential IF of 4.092MHz. IF Stage The quadrature IF signals pass through the IF filter, which rejects the out-of-band spurs by more than 60dB and the image noise by 17dB (typ). After the image reject filter, the signal is converted from quadrature to differential. The filtered IF signal is then amplified by the AGC block, which sets the VGA output signal level to a predetermined value through the application using 56dB of dynamic range. oscillator driver generates the reference frequency. The integrated synthesizer includes the VCO, crystal oscillator driver, main frequency divider, phase-frequency detector, and charge pump. It uses an off-chip PLL loop filter and crystal. If a TCXO is used, connect the output of the TCXO to XTALIN. The main division ratio for the synthesizer is 96 or 48. With this division ratio, a low-side injection LO can be used with a 16.368MHz or 32.736MHz crystal. Note that if a 3rd overtone crystal is used for the 32.736MHz, an off-chip notch filter to reject the fundamental frequency is required. The notch filter can be built with one inductor and one capacitor. Control Block This block is used mainly for testing purposes and to set the internal trimmed capacitor. This block is programmed through the VSport. VSport Serial Data Interface The serial interface within the MAX2745 is used by the baseband to communicate control signals and is also used for internal testing of the device. (This serial port is described in a separate document, which is available upon request.) Trimmed VCXO Frequency An on-chip, trimmed capacitor with a temperature coefficient of better than 30ppm/°C is used to compensate for the component variation of the reference frequency associated circuitry. The value of the capacitor is programmed in 512 binary steps and ranges from a minimum of 80fF to a maximum of 40pF, ±20%. Programming is accomplished with the VSport serial interface. The no load capacitance on the crystal out follows the equation: C(no load) = ([Register Value] x 40/512) pF Upon power-up, the capacitor value is set to the minimum value. This enables the MAX2745 to work with an off-chip, trimmed capacitor. If the baseband has the capability of programming the radio, the off-chip, trimmed capacitor can be omitted by setting the internal trimmed capacitor through the VSPORT. IF Output Selection The sampled outputs of the GPS signal are available in a single-ended or limited-differential format. The ODS pin controls the output format. Synthesizer An on-chip VCO provides quadrature differential LO signals to the downconverting mixer. An on-chip crystal 6 _______________________________________________________________________________________ Single-Chip Global Positioning System Receiver Front-End Voltage Booster The MAX2745 integrates an internal voltage booster to allow proper operation with supply voltages as low as 1.6V. The circuit includes two 6nF floating external capacitors connected to VB_CS± (pins 22 and 23) and a 1µF capacitance to VOUT (boosted voltage output, pin 24). To reduce the output voltage ripple, use an external LC lowpass filter, which can be built with two inductors and one capacitor. Applications Information Operation with Voltage Booster Under normal operating conditions, the recommended power-supply voltage ranges from 2.4V to 3.6V. But with the integrated voltage booster on-chip, the MAX2745 can be powered from power-supply voltages as low as 1.6V, and only requires a minimal number of external components. This is not the most efficient operating mode, since the power efficiency will be lowered to less than 50%. VB_CS±, pins 22 and 23, and 1µF bypass capacitor to VOUT, pin 24. Connect VOUT (pin 24) to all the powersupply (VDD) pins and pull BST_CTRL, pin 17, high to activate the booster. Then the MAX2745 can be powered from supply voltages ranging from 1.6V to 2.3V at VDD_VB, pin 19, and the voltage booster output can source up to 25mA current. It is recommended that the voltage booster be used as a backup supply. To do this, additional circuits including a voltage monitor and a switch are needed. These components are inexpensive and can be found in the Maxim product family. Layout Issues A properly designed PC board is an essential part of any RF/microwave circuit. Use the MAX2745 EV kit as a guide. Use controlled-impedance lines on all frequency inputs and outputs. Use low inductance connections to ground on all ground pins and wherever the components are connected to ground. Place decoupling capacitors close to all V CC connections. For proper operation, connect the metal exposed paddle at the back of the IC to the PC board ground plane with multiple vias. Chip Information TRANSISTOR COUNT: 9205 PROCESS: CMOS As described in the Detailed Description section, to use the voltage booster, connect 6nF floating capacitors to _______________________________________________________________________________________ 7 MAX2745 Temperature Sensor The MAX2745 features an on-chip temperature sensor to facilitate system temperature compensations in conjunction with the trimmed capacitor. This circuit generates an output voltage at TEMPOUT, which is used to approximate the temperature by the following equation: T = TO + (VOUT - VOUT,TO)/SG where SG is the sensor gain, TO is factory-trimmed temperature, which can be any value (normally +27°C), and VOUT is the temperature output voltage at TO. The coefficient SG in the above equation is targeted to be between 6mV/°C and 8mV/°C, depending on the temperature. MAX2745 Single-Chip Global Positioning System Receiver Front-End Typical Application Circuit PIN 47 TCXO RBIAS CBIAS 44 42 GND 41 VTUNE CP_OUT 43 40 39 38 37 MAX2745 1 36 BPF_CTRL VCXO 2 TEMPERATURE SENSOR PFD VDD 3 VDD 4 VDD GND SHDN 45 SDATA 46 TEMPOUT 47 VDD 48 VDD XTALIN OPTIONAL XTAL INPUT XTALOUT PIN 48 DIVIDER 35 34 CHG PUMP 33 BIAS GND 5 RFIN CFS COE 32 VDD VSPORT GND 6 fIN ODS LNA/MIXER 31 SCLK VCO 30 GND 7 1575.42MHz GND 8 29 VOUT+ VDD 9 28 VOUTBANDPASS FILTER QUANTIZER AGC IEXT_LNA 10 27 VDD VDD 11 VOLTAGE BOOSTER FILTER AUTOMATIC TUNING 8 25 VDD 18 19 XTAL_SSEL XTAL_CSEL BST_CTRL TEST_EN VDD_VB 20 21 22 23 24 VOUT 17 VB_CS- 16 VB_CS+ 15 DOUT 14 CKOUT 13 GND 12 VDD AGC_FIL 26 GND _______________________________________________________________________________________ SSingle-Chip Global Positioning System Receiver Front-End 48L,TQFP.EPS PACKAGE OUTLINE, 32/48L TQFP, 7x7x1.0mm EP OPTION 21-0065 F 1 2 PACKAGE OUTLINE, 32/48L TQFP, 7x7x1.0mm EP OPTION 21-0065 F 2 2 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9 © 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX2745 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)