general description the max2745 complete single-chip global positioning system (gps) rf front-end downconverter utilizes many innovative and leading-edge rf cmos design tech- niques. 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 pro- vides 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 tem- perature 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? to +85?) temperature range. the power consumption of this device is as low as 41mw at 2.4v. applications in-vehicle navigation systems (ivnss) location-based services (pdas and accessories) telematics (vehicle/asset tracking and inventory management) recreational handheld/walkie talkies geographical information systems (giss) emergency roadside assistance emergency response systems digital cameras/camcorders consumer electronics 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? to +85? operational temperature range max2745 single-chip global positioning system receiver front-end ________________________________________________________________ maxim integrated products 1 ordering information 19-3425; rev 0; 10/04 for pricing, delivery, and ordering information, please contact maxim/dallas direct! at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. evaluation kit available part temp range pin-package max2745ecm -40 c to +85 c 48 tqfp-ep* * ep = exposed paddle. block diagram/ pin configuration vcxo bias lna/mixer pfd divider chg pump vco temperature sensor vsport bandpass filter filter automatic tuning agc quantizer voltage booster 48 xtalin 11 v dd 12 agc_fil 25 v dd 10 iext_lna 7 rfin 9 v dd 47 xtalout 2 cbias 4 30 gnd 27 v dd 20 ckout 19 vdd_vb 1 rbias 3 v dd v dd 5 gnd 13 v dd 14 gnd 15 xtal_ssel 16 xtal_csel 17 bst_ctrl 18 test_en 21 dout 23 vb_cs- 24 v out 22 vb_cs+ 28 vout- 29 vout+ 31 sclk 32 v dd 33 coe 34 cfs 35 ods 36 bpf_ctrl 37 sdata 38 v to 39 v dd 40 vtune 41 gnd 42 cp_out 43 v dd 44 gnd 46 v dd 6 gnd 8 gnd gnd 26 45 shdn max2745 typical operating circuit appears at end of data sheet
max2745 single-chip global positioning system receiver front-end 2 _______________________________________________________________________________________ absolute maximum ratings dc electrical characteristics (max2745 ev kit, v dd = +2.4v to +3.6v, shdn = gnd, t a = -40 c to +85 c. typical values are at v dd = +3.0v and t a = +25 c, unless otherwise noted.) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. v dd to gnd ...........................................................-0.3v to +3.7v other pins to gnd......................................-0.3v to (v dd + 0.3v) rf lna input power .......................................................+10dbm continuous power dissipation (t a = +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 parameter conditions min typ max units supply voltage 2.4 3.6 v v dd = +3.0v, t a = +25 c (note 1) 20.5 27 ma supply current shutdown mode 11 a optional external lna supply current v dd = +3.0v 10 ma logic-input high voltage 2.0 v logic-input low voltage 0.5 v logic-input bias current -10 +10 a caution! esd sensitive device ac electrical characteristics (max2745 ev kit, v dd = +2.4v to +3.6v, shdn = gnd, t a = -40 c to +85 c. typical values are at v dd = +3.0v and t a = +25 c, unless otherwise noted.) parameter conditions min typ max units general performance maximum conversion gain (notes 2, 3) 105 120 db input frequency 1575.42 mhz noise figure measured at quantizer output 3.5 db return loss (s11) -14 db lna/mixer input ip3 f 1 = 5.09mhz and f 2 = 7.09mhz above carrier frequency -25 dbm output if frequency 4.092 mhz output stage differential (vout+, vout-), c l < 20pf 16 output rise/fall time single ended (dout), c l <20pf 6 ns differential v dd - 0.9 output-voltage-level low single ended 0 v differential output-voltage-level high single ended v dd v
max2745 single-chip global positioning system receiver front-end _______________________________________________________________________________________ 3 note 1: at t a = +25 c, min/max limits are guaranteed by production test. note 2: at t a = -40 c, min/max limits are guaranteed by design and characterization. note 3: at t a = +25 c and +85 c, min/max limits are guaranteed by production test. ac electrical characteristics (continued) (max2745 ev kit, v dd = +2.4v to +3.6v, shdn = gnd, t a = -40 c to +85 c. typical values are at v dd = +3.0v and t a = +25 c, unless otherwise noted.) parameter conditions min typ max units synthesizer fundamental frequency crystal 16.368 crystal input frequency 3rd overtone crystal 32.736 mhz charge-pump current 0.4 ma f offset = 10khz offset, bw loop = 70khz -81 phase noise f offset = 1mhz offset, bw loop = 70khz -104 dbc/hz maximum pll spur bw loop = 70khz -39 dbc vco tuning frequency range (notes 2, 3) 150 210 270 mhz vco tuning gain (notes 2, 3) 150 210 310 mhz/v if stage if stage gain vga set at maximum gain 80 db dynamic range if stage gain 56 db low-frequency corner 3.1 bandpass filter 1db corner frequency high-frequency corner 5.1 mhz bandpass filter 3db bandwidth 2.0 mhz bandpass filter 60db high-side rejection 6.6 mhz bandpass filter 60db low-side rejection 1.6 mhz image rejection 17 db in-band ripple 1db agc loop lock time 1ms typical operating characteristics (max2745 ev kit, v dd = +3.0v, shdn = gnd, f rf = 1575.42mhz, and t a = +25 c, unless otherwise noted.) supply current vs. temperature max2745 toc01 temperature ( c) supply current (ma) 60 40 20 0 -20 14 18 22 26 30 10 -40 80 v cc = 2.4v v cc = 2.7v v cc = 3v lna/mixer gain vs. temperature max2745 toc02 temperature ( c) lna mixer gain (db) 60 40 20 0 -20 10 5 15 20 25 30 35 40 0 -40 80 v cc = 2.4v v cc = 2.7v v cc = 3v if stage gain vs. temperature max2745 toc03 temperature ( c) if stage gain (db) 60 40 20 0 -20 70 65 75 80 85 90 95 100 60 -40 80 v cc = 2.4v v cc = 2.7v v cc = 3v
max2745 single-chip global positioning system receiver front-end 4 _______________________________________________________________________________________ pin name function 1 rbias external bias resistor. for normal bias, connect a 100k ? (1%) resistor to ground. 2 cbias bias bypass capacitor. connect a 0.1f capacitor to ground. 3, 4, 9, 11, 13, 25, 27, 32, 39, 43, 46 v dd power-supply voltage. bypass with a 0.1f capacitor to ground as close to the pins as possible. 5, 6, 8, 14, 26, 30, 41, 44 gnd ground 7 rfin rf input signal. requires external matching network. 10 iext_lna external lna voltage supply 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 connect to ground for normal operation 19 vdd_vb power supply for voltage booster. connect to v dd if voltage booster is not used. 20 ckout full-swing clock output 21 dout single-ended full-swing digital output 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 v out voltage booster output. bypass to gnd with a 1f capacitor as close to the pin as possible. pin description typical operating characteristics (continued) (max2745 ev kit, v dd = +3.0v, shdn = gnd, f rf = 1575.42mhz, and t a = +25 c, unless otherwise noted.) total gain vs. temperature max2745 toc04 temperature ( c) total gain (db) 60 40 20 0 -20 102 104 106 108 110 100 -40 80 v cc = 2.4v v cc = 2.7v v cc = 3v 0 0.4 0.2 0.8 0.6 1.4 1.2 1.0 1.6 -40 0 -20 20 40 60 80 temperature-sensor output voltage vs. temperature max4725 toc05 temperature ( c) temperature-sensor output voltage, v to (v) v dd = 3.6v v dd = 2.4v 2.0 2.4 2.2 2.8 2.6 3.0 3.2 1.6 1.9 2.0 1.7 1.8 2.1 2.2 2.3 voltage-booster output vs. vdd_vb max2745 toc06 vdd_vb (v) voltage-booster output, v out (v) t a = -40 c bst_ctrl = high v out = v dd t a = +25 c t a = +85 c
max2745 single-chip global positioning system receiver front-end _______________________________________________________________________________________ 5 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 limited- swing output. 36 bpf_ctrl bandpass filter (bpf) control. drive logic high to activate the tuning block control bpf. drive logic low to let bpf be controlled by fuses. 37 sdata serial port data (bidirectional pad) 38 tempout temperature sense dc voltage output 40 vtune vco tuning input 42 cp_out pll charge-pump output. analog high-impedance output. current source. connect directly to the pll loop filter input. 45 shdn active-high shutdown input. drive logic low to disable all device functions. drive logic high for normal operation. 47 xtalout crystal output. connect directly to the external crystal. 48 xtalin crystal input. connect directly to the external crystal or tcxo. pin description (continued) functional diagram image rejection bpf vga agc temp sensor digital control voltage booster power switch bpf 1.57542ghz shutdown vdd1v6 vsport temp sensor dc output pll loop filter /96 /48 pfd lna cp mux clock freq control clock output control clock output: 16.368mhz 32.768mhz 16.368mhz 32.768mhz quantizer 4.092mhz if output: full swing differential limited swing output control max2745
max2745 single-chip global positioning system receiver front-end 6 _______________________________________________________________________________________ detailed description the max2745 complete single-chip gps front-end downconverter utilizes many innovative and leading- edge rf cmos design techniques. this high-perfor- mance, 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 pro- vides 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 tempera- ture sensor and crystal oscillator with trimmed capaci- tors, 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 band- width 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 speci- fied 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 sig- nal 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. 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 oscillator driver generates the reference frequency. the integrated synthesizer includes the vco, crystal oscil- lator 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 induc- tor and one capacitor. control block this block is used mainly for testing purposes and to set the internal trimmed capacitor. this block is pro- grammed 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 coeffi- cient 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 pro- grammed in 512 binary steps and ranges from a mini- mum of 80ff to a maximum of 40pf, 20%. pro- gramming is accomplished with the vsport serial inter- face. 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 mini- mum 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 inter- nal trimmed capacitor through the vsport.
max2745 single-chip global positioning system receiver front-end _______________________________________________________________________________________ 7 temperature sensor the max2745 features an on-chip temperature sensor to facilitate system temperature compensations in conjunc- tion with the trimmed capacitor. this circuit generates an output voltage at tempout, which is used to approxi- mate the temperature by the following equation: t = t o + (v out - v out,to )/sg where sg is the sensor gain, t o is factory-trimmed tem- perature, which can be any value (normally +27 c), and v out is the temperature output voltage at t o . the coeffi- cient sg in the above equation is targeted to be between 6mv/ c and 8mv/ c, depending on the temperature. 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 1f capacitance to v out (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 low- ered to less than 50%. as described in the detailed description section, to use the voltage booster, connect 6nf floating capacitors to vb_cs , pins 22 and 23, and 1f bypass capacitor to v out , pin 24. connect v out (pin 24) to all the power- supply (v dd ) pins and pull bst_ctrl, pin 17, high to activate the booster. then the max2745 can be pow- ered 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 inexpen- sive 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 compo- nents 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 multi- ple vias. chip information transistor count: 9205 process: cmos
max2745 single-chip global positioning system receiver front-end 8 _______________________________________________________________________________________ typical application circuit vcxo bias lna/mixer pfd divider chg pump vco temperature sensor vsport bandpass filter filter automatic tuning agc quantizer voltage booster 1 2 3 4 5 6 7 8 9 10 11 12 36 35 34 33 32 31 30 29 28 27 25 13 14 15 16 17 18 19 20 21 22 23 24 48 47 46 45 44 43 42 41 40 39 38 37 xtalin v dd agc_fil v dd iext_lna rfin f in v dd xtalout cbias v dd gnd v dd ckout vdd_vb rbias v dd gnd v dd gnd xtal_ssel xtal_csel bst_ctrl test_en dout vb_cs- v out vb_cs+ gnd vout- vout+ sclk v dd coe cfs ods bpf_ctrl sdata tempout v dd vtune gnd cp_out v dd gnd v dd gnd gnd 1575.42mhz 26 shdn max2745 tcxo optional xtal input pin 47 pin 48
max2745 ssingle-chip global positioning system receiver front-end maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it 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. package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation, go to www.maxim-ic.com/packages .) 48l,tqfp.eps f 1 2 21-0065 package outline, 32/48l tqfp, 7x7x1.0mm ep option f 2 2 21-0065 package outline, 32/48l tqfp, 7x7x1.0mm ep option
e nglish ? ???? ? ??? ? ??? what's ne w p roducts solutions de sign ap p note s sup p ort buy comp any me mbe rs max2745 part number table notes: see the max2745 quickview data sheet for further information on this product family or download the max2745 full data sheet (pdf, 416kb). 1. other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales . 2. didn't find what you need? ask our applications engineers. expert assistance in finding parts, usually within one business day. 3. part number suffixes: t or t&r = tape and reel; + = rohs/lead-free; # = rohs/lead-exempt. more: see full data sheet or part naming c onventions . 4. * some packages have variations, listed on the drawing. "pkgc ode/variation" tells which variation the product uses. 5. part number free sample buy direct package: type pins size drawing code/var * temp rohs/lead-free? materials analysis max2745ec m+d tqfp;48 pin;7x7x1 mm dwg: 21-0065g (pdf) use pkgcode/variation: c 48e+8 * -40c to +85c rohs/lead-free: yes materials analysis max2745ec m+ -40c to +85c rohs/lead-free: yes max2745ec m+t -40c to +85c rohs/lead-free: yes max2745ec m+td tqfp;48 pin;7x7x1 mm dwg: 21-0065g (pdf) use pkgcode/variation: c 48e+8 * -40c to +85c rohs/lead-free: yes materials analysis didn't find what you need? c ontac t us: send us an email c opyright 2 0 0 7 by m axim i ntegrated p roduc ts , dallas semic onduc tor ? legal n otic es ? p rivac y p olic y
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