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for free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. for small orders, phone 1-800-835-8769. general description the MAX2680/max2681/max2682 miniature, low-cost, low-noise downconverter mixers are designed for low- voltage operation and are ideal for use in portable com- munications equipment. signals at the rf input port are mixed with signals at the local oscillator (lo) port using a double-balanced mixer. these downconverter mixers operate with rf input frequencies between 400mhz and 2500mhz, and downconvert to if output frequencies between 10mhz and 500mhz. the MAX2680/max2681/max2682 operate from a sin- gle +2.7v to +5.5v supply, allowing them to be pow- ered directly from a 3-cell nicd or a 1-cell lithium battery. these devices offer a wide range of supply currents and input intercept (iip3) levels to optimize system performance. additionally, each device features a low-power shutdown mode in which it typically draws less than 0.1? of supply current. consult the selector guide for various combinations of iip3 and supply cur- rent. the MAX2680/max2681/max2682 are manufactured on a high-frequency, low-noise, advanced silicon-ger- manium process and are offered in the space-saving 6-pin sot23 package. applications 400mhz/900mhz/2.4ghz ism-band radios personal communications systems (pcs) cellular and cordless phones wireless local loop ieee-802.11 and wireless data features 400mhz to 2.5ghz operation +2.7v to +5.5v single-supply operation low noise figure: 6.3db at 900mhz (MAX2680) high input third-order intercept point (iip3 at 2450mhz) -6.9dbm at 5.0ma (MAX2680) +1.0dbm at 8.7ma (max2681) +3.2dbm at 15.0ma (max2682) <0.1a low-power shutdown mode ultra-small surface-mount packaging MAX2680/max2681/max2682 400mhz to 2.5ghz, low-noise, sige downconverter mixers ________________________________________________________________ maxim integrated products 1 gnd ifout rfin 16 shdn 5 v cc lo MAX2680 max2681 max2682 sot23-6 top view 2 34 19-4786; rev 2; 8/03 part MAX2680 eut-t max2681 eut-t max2682 eut-t -40? to +85? -40? to +85? -40? to +85? temp range pin- package 6 sot23-6 6 sot23-6 6 sot23-6 evaluation kit available pin configuration ordering information sot top mark aaar aaas aaat 8.7 max2681 5.0 MAX2680 selector guide part i cc (ma) -6.1 iip3 (dbm) -12.9 7.0 nf (db) 6.3 14.2 gain (db) 11.6 900mhz +0.5 iip3 (dbm) -8.2 11.1 nf (db) 8.3 8.4 gain (db) 7.6 1950mhz +1.0 iip3 (dbm) -6.9 12.7 nf (db) 11.7 7.7 gain (db) 7.0 2450mhz -1.8 15.0 max2682 6.5 14.7 +4.4 10.2 10.4 +3.2 13.4 7.9 typical operating circuit appears at end of data sheet. frequency
MAX2680/max2681/max2682 400mhz to 2.5ghz, low-noise, sige downconverter mixers 2 _______________________________________________________________________________________ absolute maximum ratings dc electrical characteristics (v cc = +2.7v to +5.5v, shdn = +2v, t a = t min to t max unless otherwise noted. typical values are at v cc = +3v and t a = +25?. minimum and maximum values are guaranteed over temperature by design and characterization.) 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 cc to gnd ..........................................................-0.3v to +6.0v rfin input power (50 ? source).....................................+10dbm lo input power (50 ? source) ........................................+10dbm shdn , ifout, rfin to gnd ......................-0.3v to (v cc + 0.3v) lo to gnd..........................................(v cc - 1v) to (v cc + 0.3v) continuous power dissipation (t a = +70?) sot23-6 (derate 8.7mw/? above +70?)..................696mw operating temperature range ..........................-40? to +85? junction temperature ......................................................+150? storage temperature range .............................-65? to +160? lead temperature (soldering, 10s) .................................+300? max2682 max2681 MAX2680 shdn = 0.5v 0 < shdn < v cc conditions ma 15.0 21.8 i cc operating supply current 8.7 12.7 5.0 7.7 ? 0.05 5 i cc shutdown supply current v 2.0 v ih shutdown input voltage high v 0.5 v il shutdown input voltage low ? 0.2 i shdn shutdown input bias current units min typ max symbol parameter (notes 1, 2) (notes 1, 2) 50 ? source impedance f rf = 1950mhz, 1951mhz, f lo = 1880mhz, f if = 70mhz f rf = 900mhz, 901mhz, f lo = 970mhz, f if = 70mhz f rf = 2450mhz, f lo = 2210mhz, f if = 240mhz f rf = 1950mhz, f lo = 2020mhz, f if = 70mhz f rf = 2450mhz, f lo = 2210mhz, f if = 240mhz (notes 1, 2) f rf = 400mhz, f lo = 445mhz, f if = 45mhz f rf = 900mhz, f lo = 970mhz, f if = 70mhz f rf = 900mhz, f lo = 970mhz, f if = 70mhz f rf = 1950mhz, f lo = 1880mhz, f if = 70mhz (note 1) f rf = 2450mhz, 2451mhz, f lo = 2210mhz, f if = 240mhz conditions 1.5:1 lo input vswr db 11.7 noise figure (single sideband) 8.3 6.3 dbm -6.9 input third-order intercept point (note 3) mhz 400 2500 lo frequency range mhz 400 2500 rf frequency range -8.2 -12.9 db 7.0 conversion power gain mhz 10 500 if frequency range 7.3 11.6 5.7 7.6 8.6 units min typ max parameter ac electrical characteristics (MAX2680/1/2 ev kit, v cc = shdn = +3.0v, t a = +25?, unless otherwise noted. rfin and ifout matched to 50 ? . p lo = -5dbm, p rfin = -25dbm.) f rf = 1950mhz, f lo = 1880mhz, f if = 70mhz, t a = t min to t max (note 1) db 1.9 2.4 gain variation over temperature f lo = 1880mhz dbm -22 lo leakage at ifout port MAX2680 caution! esd sensitive device
MAX2680/max2681/max2682 400mhz to 2.5ghz, low-noise, sige downconverter mixers _______________________________________________________________________________________ 3 ac electrical characteristics (continued) (MAX2680/1/2 ev kit, v cc = shdn = +3.0v, t a = +25?, unless otherwise noted. rfin and ifout matched to 50 ? . p lo = -5dbm, p rfin = -25dbm.) f rf = 1950mhz, f lo = 1880mhz, f if = 70mhz, t a = t min to t max (note 1) db 1.7 2.3 (notes 1, 2) gain variation over temperature f lo = 1880mhz (notes 1, 2) f lo = 1880mhz dbm 50 ? source impedance f rf = 1950mhz, 1951mhz, f lo = 1880mhz, f if = 70mhz f rf = 900mhz, 901mhz, f lo = 970mhz, f if = 70mhz f rf = 2450mhz, f lo = 2210mhz, f if = 240mhz f rf = 1950mhz, f lo = 2020mhz, f if = 70mhz -27 f rf = 2450mhz, f lo = 2210mhz, f if = 240mhz (notes 1, 2) f rf = 400mhz, f lo = 445mhz, f if = 45mhz f rf = 900mhz, f lo = 970mhz, f if = 70mhz f rf = 900mhz, f lo = 970mhz, f if = 70mhz f rf = 1950mhz, f lo = 1880mhz, f if = 70mhz (note 1) f rf = 2450mhz, 2451mhz, f lo = 2210mhz, f if = 240mhz conditions lo leakage at rfin port dbm -23 lo leakage at ifout port f rf = 1915mhz, f lo = 1880mhz, f if = 70mhz (note 4) dbm -65 if/2 spurious response 1.5:1 lo input vswr db 12.7 noise figure (single sideband) 11.1 7.0 dbm +1.0 input third-order intercept point (note 3) mhz 400 2500 lo frequency range mhz 400 2500 rf frequency range +0.5 -6.1 db 7.7 conversion power gain mhz 10 500 if frequency range 11.0 14.2 6.7 8.4 9.4 units min typ max parameter f rf = 1950mhz, f lo = 1880mhz, f if = 70mhz, t a = t min to t max (note 1) db 2.1 3.2 (notes 1, 2) gain variation over temperature (notes 1, 2) f rf = 1950mhz, 1951mhz, f lo = 1880mhz, f if = 70mhz f rf = 900mhz, 901mhz, f lo = 970mhz, f if = 70mhz f rf = 2450mhz, f lo = 2210mhz, f if = 240mhz (notes 1, 2) f rf = 400mhz, f lo = 445mhz, f if = 45mhz f rf = 900mhz, f lo = 970mhz, f if = 70mhz f rf = 1950mhz, f lo = 1880mhz, f if = 70mhz (note 1) f rf = 2450mhz, 2451mhz, f lo = 2210mhz, f if = 240mhz dbm +3.2 input third-order intercept point (note 3) mhz 400 2500 lo frequency range mhz 400 2500 rf frequency range +4.4 -1.8 db 7.9 conversion power gain mhz 10 500 if frequency range 13.4 14.7 8.7 10.4 11.7 f rf = 1950mhz, f lo = 2020mhz, f if = 70mhz f rf = 900mhz, f lo = 970mhz, f if = 70mhz f rf = 2450mhz, f lo = 2210mhz, f if = 240mhz db 13.4 noise figure (single sideband) 10.2 6.5 f lo = 1880mhz dbm -26 lo leakage at rfin port f rf = 1915mhz, f lo = 1880mhz, f if = 70mhz (note 4) dbm -51 if/2 spurious response max2681 max2682
2 3 5 4 6 7 2.5 3.5 3.0 4.0 4.5 5.0 5.5 MAX2680 supply current vs. supply voltage MAX2680/1/2-01 supply voltage (v) supply current (ma) t a = +85? t a = +25? t a = -40? shdn = v cc 5 6 8 7 9 10 2.5 3.5 3.0 4.0 4.5 5.0 5.5 max2681 supply current vs. supply voltage MAX2680/1/2-02 supply voltage (v) supply current (ma) t a = +85 c shdn = v cc t a = +25 c t a = -40 c 8 11 10 9 12 13 14 15 16 17 18 2.5 3.5 3.0 4.0 4.5 5.0 5.5 max2682 supply current vs. supply voltage MAX2680/1/2-03 supply voltage (v) supply current (ma) t a = +85 c t a = +25 c t a = -40 c shdn = v cc MAX2680/max2681/max2682 400mhz to 2.5ghz, low-noise, sige downconverter mixers 4 _______________________________________________________________________________________ ac electrical characteristics (continued) (MAX2680/1/2 ev kit, v cc = shdn = +3.0v, t a = +25?, unless otherwise noted. rfin and ifout matched to 50 ? . p lo = -5dbm, p rfin = -25dbm.) f lo = 1880mhz f lo = 1880mhz dbm 50 ? source impedance -27 conditions lo leakage at rfin port dbm -23 lo leakage at ifout port f rf = 1915mhz, f lo = 1880mhz, f if = 70mhz (note 4) dbm -61 if/2 spurious response 1.5:1 lo input vswr units min typ max parameter note 1: guaranteed by design and characterization. note 2: operation outside of this specification is possible, but performance is not characterized and is not guaranteed. note 3: two input tones at -25dbm per tone. note 4: this spurious response is caused by a higher-order mixing product (2x2). specified rf frequency is applied and if output power is observed at the desired if frequency (70mhz). typical operating characteristics (typical operating circuit, v cc = shdn = +3.0v, p rfin = -25dbm, p lo = -5dbm, t a = +25?, unless otherwise noted.)
MAX2680/max2681/max2682 400mhz to 2.5ghz, low-noise, sige downconverter mixers _______________________________________________________________________________________ 5 0 0.03 0.02 0.01 0.04 0.05 0.06 0.07 0.08 0.09 0.10 2.5 3.5 3.0 4.0 4.5 5.0 5.5 MAX2680 shutdown supply current vs. supply voltage MAX2680/1/2-04 supply voltage (v) shutdown supply current ( a) t a = +85 c t a = +25 c t a = -40 c shdn = gnd -1 5 3 1 7 9 11 13 15 -14 -10 -8 -12 -6 -4 -2 0 MAX2680 conversion power gain vs. lo power MAX2680/1/2-07 lo power (dbm) conversion power gain (db) f rf 900mhz 1950mhz 2450mhz f lo 970mhz 1880mhz 2210mhz f if 70mhz 70mhz 240mhz f rf = 900mhz f rf = 2450mhz f rf = 1950mhz 0 0.03 0.02 0.01 0.04 0.05 0.06 0.07 0.08 0.09 0.10 2.5 3.5 3.0 4.0 4.5 5.0 5.5 max2681 shutdown supply current vs. supply voltage MAX2680/1/2-05 supply voltage (v) shutdown supply current ( a) t a = +85 c t a = +25 c t a = -40 c shdn = gnd 0 0.03 0.02 0.01 0.04 0.05 0.06 0.07 0.08 0.09 0.10 2.5 3.5 3.0 4.0 4.5 5.0 5.5 max2682 shutdown supply current vs. supply voltage MAX2680/1/2-06 supply voltage (v) shutdown supply current ( a) t a = +85 c t a = +25 c t a = -40 c shdn = gnd 0 6 4 2 8 10 12 14 16 -14 -10 -8 -12 -6 -4 -2 0 max2681 conversion power gain vs. lo power MAX2680/1/2-08 lo power (dbm) conversion power gain (db) f rf = 900mhz f rf = 1950mhz f rf = 2450mhz f rf 900mhz 1950mhz 2450mhz f lo 970mhz 1880mhz 2210mhz f if 70mhz 70mhz 240mhz 0 6 4 2 8 10 12 14 16 -14 -10 -8 -12 -6 -4 -2 0 max2682 conversion power gain vs. lo power MAX2680/1/2-09 lo power (dbm) conversion power gain (db) f rf = 900mhz f rf = 1950mhz f rf = 2450mhz f rf 900mhz 1950mhz 2450mhz f lo 970mhz 1880mhz 2210mhz f if 70mhz 70mhz 240mhz typical operating characteristics (continued) (typical operating circuit, v cc = shdn = +3.0v, p rfin = -25dbm, p lo = -5dbm, t a = +25?, unless otherwise noted.) 0 6 4 2 8 10 12 14 16 -40 0 20 -20 40 60 80 100 MAX2680 conversion power gain vs. temperature MAX2680/1/2-10 temperature ( c) conversion power gain (db) f rf = 900mhz f rf = 1950mhz f rf = 2450mhz f rf 900mhz 1950mhz 2450mhz f lo 970mhz 1880mhz 2210mhz f if 70mhz 70mhz 240mhz 0 6 4 2 8 10 12 14 16 -40 0 20 -20 40 60 100 80 max2681 conversion power gain vs. temperature MAX2680/1/2-11 temperature ( c) conversion power gain (db) f rf = 900mhz f rf = 1950mhz f rf = 2450mhz 1 7 5 3 9 11 13 15 17 -40 0 20 -20 40 60 80 100 max2682 conversion power gain vs. temperature MAX2680/1/2-12 temperature ( c) conversion power gain (db) f rf = 900mhz f rf = 1950mhz f rf = 2450mhz
MAX2680/max2681/max2682 400mhz to 2.5ghz, low-noise, sige downconverter mixers 6 _______________________________________________________________________________________ typical operating characteristics (continued) (typical operating circuit, v cc = shdn = +3.0v, p rfin = -25dbm, p lo = -5dbm, t a = +25?, unless otherwise noted.) -10 -8 -9 -7 -6 -5 -14 -10 -8 -12 -6 -4 -2 0 MAX2680 input ip3 vs. lo power MAX2680/1/2-13 lo power (dbm) input ip3 (dbm) f rf = 1950mhz, 1951mhz f lo = 1880mhz f if = 70mhz p rfin = -25dbm per tone -3 -1 -2 0 1 2 -14 -10 -8 -12 -6 -4 -2 0 max2681 input ip3 vs. lo power MAX2680/1/2-14 lo power (dbm) input ip3 (dbm) f rf = 1950mhz, 1951mhz f lo = 1880mhz f if = 70mhz p rfin = -25dbm per tone 0 3 2 4 1 5 6 7 -14 -10 -8 -12 -6 -4 -2 0 max2682 input ip3 vs. lo power MAX2680/1/2-15 lo power (dbm) input ip3 (dbm) f rf = 1950mhz, 1951mhz f lo = 1880mhz f if = 70mhz p rfin = -25dbm per tone 0 6 4 10 8 2 12 14 16 -14 -10 -8 -12 -6 -4 -2 0 MAX2680 noise figure vs. lo power MAX2680/1/2-16 lo power (dbm) noise figure (db) f rf = 900mhz f rf = 1950mhz f rf = 2450mhz f rf 900mhz 1950mhz 2450mhz f lo 970mhz 2020mhz 2210mhz f if 70mhz 70mhz 70mhz 0 150 100 50 200 250 300 0 1000 500 1500 2000 2500 MAX2680 rf port impedance vs. rf frequency MAX2680/1/2-19 rf frequency (mhz) real impedance ( ? ) -600 -300 -400 -500 -200 -100 0 imaginary impedance ( ? ) imaginary real f lo = 970mhz p lo = -5dbm 0 8 6 14 12 10 2 4 16 18 20 -14 -10 -8 -12 -6 -4 -2 0 max2681 noise figure vs. lo power MAX2680/1/2-17 lo power (dbm) noise figure (db) f rf = 900mhz f rf = 1950mhz f rf = 2450mhz f rf 900mhz 1950mhz 2450mhz f lo 970mhz 2020mhz 2210mhz f if 70mhz 70mhz 70mhz 0 10 5 15 20 25 -14 -10 -8 -12 -6 -4 -2 0 max2682 noise figure vs. lo power MAX2680/1/2-18 lo power (dbm) noise figure (db) f rf = 900mhz f rf = 1950mhz f rf = 2450mhz f rf 900mhz 1950mhz 2450mhz f lo 970mhz 2020mhz 2210mhz f if 70mhz 70mhz 70mhz 0 150 100 50 200 250 300 0 500 1000 1500 2000 2500 max2681 rf port impedance vs. rf frequency MAX2680/1/2-20 rf frequency (mhz) real impedance ( ? ) imaginary real f lo = 970mhz p lo = -5dbm -600 -300 -400 -500 -200 -100 0 imaginary impedance ( ? ) 0 150 100 50 200 250 300 0 1000 500 1500 2000 2500 max2682 rf port impedance vs. rf frequency MAX2680/1/2-21 rf frequency (mhz) real impedance ( ? ) -600 -300 -400 -500 -200 -100 0 imaginary impedance ( ? ) imaginary real f lo = 970mhz p lo = -5dbm
MAX2680/max2681/max2682 400mhz to 2.5ghz, low-noise, sige downconverter mixers _______________________________________________________________________________________ 7 0 600 400 200 800 1000 1200 0 200 100 300 400 500 MAX2680 if port impedance vs. if frequency MAX2680/1/2-22 if frequency (mhz) real impedance ( ? ) -600 -300 -400 -500 -200 -100 0 imaginary impedance ( ? ) imaginary real f lo = 970mhz p lo = -5dbm 0 600 400 200 800 1000 1200 0 200 100 300 400 500 max2681 if port impedance vs. if frequency MAX2680/1/2-23 if frequency (mhz) real impedance ( ? ) -600 -300 -400 -500 -200 -100 0 imaginary impedance ( ? ) imaginary real f lo = 970mhz p lo = -5dbm 0 300 200 100 500 400 600 700 800 0 200 100 300 400 500 max2682 if port impedance vs. if frequency MAX2680/1/2-24 if frequency (mhz) real impedance ( ? ) -400 -350 -250 -200 -300 -150 -50 -100 0 imaginary impedance ( ? ) imaginary real f lo = 970mhz p lo = -5dbm -40 -30 -35 -20 -25 -10 -15 -5 +5 0 +10 200 760 1320 1880 2440 3000 MAX2680 lo port return loss MAX2680/1/2-25 frequency (mhz) return loss (db) 0 10 5 20 15 30 25 35 0 1000 500 1500 2000 2500 MAX2680 lo-to-if and lo-to-rf isolation MAX2680/1/2-28 lo frequency (mhz) isolation (db) lo-to-if isolation lo-to-rf isolation -40 -30 -35 -20 -25 -10 -15 -5 +5 0 +10 200 760 1320 1880 2440 3000 max2681 lo port return loss MAX2680/1/2-26 frequency (mhz) return loss (db) -40 -30 -35 -20 -25 -10 -15 -5 +5 0 +10 200 760 1320 1880 2440 3000 max2682 lo port return loss MAX2680/1/2-27 frequency (mhz) return loss (db) 0 10 5 25 20 15 35 30 40 0 1000 500 1500 2000 2500 max2681 lo-to-if and lo-to-rf isolation MAX2680/1/2-29 lo frequency (mhz) isolation (db) lo-to-if isolation lo-to-rf isolation 10 15 25 20 30 35 0 1000 500 1500 2000 2500 max2682 lo-to-if and lo-to-rf isolation MAX2680/1/2-30 lo frequency (mhz) isolation (db) lo-to-if isolation lo-to-rf isolation typical operating characteristics (continued) (typical operating circuit, v cc = shdn = +3.0v, p rfin = -25dbm, p lo = -5dbm, t a = +25?, unless otherwise noted.)
MAX2680/max2681/max2682 400mhz to 2.5ghz, low-noise, sige downconverter mixers 8 _______________________________________________________________________________________ typical operating characteristics (continued) (typical operating circuit, v cc = shdn = +3.0v, p rfin = -25dbm, p lo = -5dbm, t a = +25?, unless otherwise noted.) pin description shdn 2v/div ifout 50mv/ div 500ns/div MAX2680 turn-off/on characteristics MAX2680/1/2-31 z1 = 39pf shdn 2v/div ifout 50mv/ div 500ns/div max2681 turn-off/on characteristics MAX2680/1/2-32 z1 = 39pf shdn 2v/div ifout 50mv/ div 500ns/div max2682 turn-off/on characteristics MAX2680/1/2-33 z2 = 39pf pin local-oscillator input. apply a local-oscillator signal with an amplitude of -10dbm to 0 (50 ? source). ac- couple this pin to the oscillator with a dc-blocking capacitor. nominal dc voltage is v cc - 0.4v. lo 1 function name mixer ground. connect to the ground plane with a low-inductance connection. gnd 2 intermediate frequency output. open-collector output requires an inductor to v cc . ac-couple to this pin with a dc-blocking capacitor. see applications information section for details on impedance matching. ifout 4 radio frequency input. ac-couple to this pin with a dc-blocking capacitor. nominal dc voltage is 1.5v. see applications information section for details on impedance matching. rfin 3 supply voltage input, +2.7v to +5.5v. bypass with a capacitor to the ground plane. capacitor value depends upon desired operating frequency. v cc 5 active-low shutdown. drive low to disable all device functions and reduce the supply current to less than 5?. for normal operation, drive high or connect to v cc . shdn 6
detailed description the MAX2680/max2681/max2682 are 400mhz to 2.5ghz, silicon-germanium, double-balanced down- converter mixers. they are designed to provide opti- mum linearity performance for a specified supply current. they consist of a double-balanced gilbert-cell mixer with single-ended rf, lo, and if port connec- tions. an on-chip bias cell provides a low-power shut- down feature. consult the selector guide for device features and comparison. applications information local-oscillator (lo) input the lo input is a single-ended broadband port with a typical input vswr of better than 2.0:1 from 400mhz to 2.5ghz. the lo signal is mixed with the rf input sig- nal, and the resulting downconverted output appears at ifout. ac-couple lo with a capacitor. drive the lo port with a signal ranging from -10dbm to 0 (50 ? source). rf input the rf input frequency range is 400mhz to 2.5ghz. the rf input requires an impedance-matching network as well as a dc-blocking capacitor that can be part of the matching network. consult tables 1 and 2, as well as the rf port impedance vs. rf frequency graph in the typical operating characteristics for information on matching. if output the if output frequency range extends from 10mhz to 500mhz. ifout is a high-impedance, open-collector output that requires an external inductor to v cc for proper biasing. for optimum performance, the if port requires an impedance-matching network. the configu- ration and values for the matching network is depen- dent upon the frequency and desired output impedance. for assistance in choosing components for optimal performance, refer to tables 3 and 4 as well as the if port impedance vs. if frequency graph in the typical operating characteristics. power-supply and s s h h d d n n bypassing proper attention to voltage supply bypassing is essen- tial for high-frequency rf circuit stability. bypass v cc with a 10? capacitor in parallel with a 1000pf capaci- tor. use separate vias to the ground plane for each of the bypass capacitors and minimize trace length to reduce inductance. use separate vias to the ground plane for each ground pin. use low-inductance ground connections. decouple shdn with a 1000pf capacitor to ground to minimize noise on the internal bias cell. use a series resistor (typically 100 ? ) to reduce coupling of high-fre- quency signals into the shdn pin. layout issues a well designed pc board is an essential part of an rf circuit. for best performance, pay attention to power- supply issues as well as to the layout of the rfin and ifout impedance-matching network. MAX2680/max2681/max2682 400mhz to 2.5ghz, low-noise, sige downconverter mixers _______________________________________________________________________________________ 9 179-j356 MAX2680 table 1. rfin port impedance 54-j179 32-j94 33-j73 frequency 75-j188 209-j332 max2681 34-j108 33-j86 78-j182 206-j306 max2682 34-j106 29-j86 table 2. rf input impedance-matching component values 270pf 86nh z1 1.5pf short MAX2680 22nh 270pf z2 270pf 270pf open open z3 1.8nh 1.8nh note: z1, z2, and z3 are found in the typical operating circuit. 270pf 68nh 1.5pf short max2681 18nh 270pf 270pf 270pf open 0.5pf 1.8nh 2.2nh 1.5pf 68nh short short max2682 270pf 270pf 270pf 270pf 10nh 0.5pf 2.2nh 1.2nh 900 mhz 1950 mhz 2450 mhz 900 mhz 1950 mhz 2450 mhz 400 mhz 900 mhz 1950 mhz 400 mhz 2450 mhz 400 mhz 900mhz 1950mhz 2450mhz part 400mhz frequency matching components
MAX2680/max2681/max2682 power-supply layout to minimize coupling between different sections of the ic, the ideal power-supply layout is a star configuration with a large decoupling capacitor at a central v cc node. the v cc traces branch out from this central node, each going to a separate v cc node on the pc board. at the end of each trace is a bypass capacitor that has low esr at the rf frequency of operation. this arrangement provides local decoupling at the v cc pin. at high frequencies, any signal leaking out of one sup- ply pin sees a relatively high impedance (formed by the v cc trace inductance) to the central v cc node, and an even higher impedance to any other supply pin, as well as a low impedance to ground through the bypass capacitor. impedance-matching network layout the rfin and ifout impedance-matching networks are very sensitive to layout-related parasitics. to minimize parasitic inductance, keep all traces short and place components as close as possible to the chip. to mini- mize parasitic capacitance, use cutouts in the ground plane (and any other plane) below the matching network components. however, avoid cutouts that are larger than necessary since they act as aperture antennas. 400mhz to 2.5ghz, low-noise, sige downconverter mixers 10 ______________________________________________________________________________________ table 3. ifout port impedance 803-j785 960-j372 MAX2680 186-j397 frequency 746-j526 934-j373 max2681 161-j375 578-j299 670-j216 max2682 175-j296 table 4. if output impedance-matching components 330nh 390nh l1 82nh frequency 15pf 39pf c2 3pf open 250 ? r1 open 70mhz 240mhz part 45mhz 70mhz 240mhz matching component 45mhz MAX2680 max2681 max2682 lo c3 6 5 4 shutdown control 1 shdn v cc rf input lo input c1 ifout 2 z 2 z 3 z 1 3 gnd rfin the values of matching components c2, l1, r1, z1, z2, and z3 depend on the if and rf frequency and downconverter. see tables 2 and 4. v cc +2.7v to +5.5v if output l1 c2 r1 c4 1000pf c5 10 f typical operating circuit
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 ____________________ 11 2003 maxim integrated products printed usa is a registered trademark of maxim integrated products. 400mhz to 2.5ghz, low-noise, sige downconverter mixers 6lsot.eps f 1 1 21-0058 package outline, sot-23, 6l 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 .)

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