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1 typical application features description 20db gain block, 50 if amplifier the lt c ? 6431-20 is a gain block amplifier exhibiting excellent linearity at frequencies beyond 1000 mhz and with low associated output noise. the unique combination of linearity, low noise and low power dissipation make this an ideal candidate for many signal-chain applications. the ltc6431-20 is easy to use, requiring a minimum of external components. it is internally input/output matched to 50 and it draws only 93ma from a single 5v supply. on-chip bias and temperature compensation maintain performance over environmental changes. the ltc6431-20 uses a high performance sige bicmos process for excellent repeatability compared with similar gaas amplifiers. all a- grade ltc6431-20 devices are tested and guaranteed for oip3 at 240 mhz. the ltc6431-20 is housed in a 4mm 4mm 24- lead qfn package with an exposed pad for thermal management and low inductance. ltc6431 family gain ltc6431-15 15.5db ltc6431-20 20.8db applications n 50 matched 20mhz to 1400mhz n 20.8db power gain n 46.2dbm oip3 at 240mhz into 50 n nf = 2.6db at 240mhz n 0.6nv/hz total input noise n s11 < C10db up to 2.0ghz n s22 < C10db up to 1.4ghz n >2.0v p-p linear output swing n p1db = 22.0dbm n 50 single-ended input/output n insensitive to v cc variation n a-grade 100% oip3 tested at 240mhz n input/output internally matched to 50 n single 5v supply n single-ended if amplifier n adc driver n catv l, lt , lt c , lt m , linear technology and the linear logo are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. single-ended if amplifier oip3 vs frequency 50 ltc6431-20 v cc = 5v 1000pf 50 643120 ta01a rf choke 560nh 5v 1000pf frequency (mhz) 0 oip3 (dbm) 42 44 46 600 1000 643120 ta01b 40 38 36 200 400 800 48 50 52 v cc = 5v t a = 25c p out = 2dbm/tone f space = 1mhz z in = z out = 50 ltc 6431-20 643120f for more information www.linear.com/ltc6431-20
2 pin configuration absolute maximum ratings total supply voltage (v cc to gnd )........................... 5.5 v amplifier output current (+ out ) ......................... 12 0 ma rf input power , continuous , 50 ( note 2) .......... 15 dbm rf input power , 100 s pulse , 50 ( note 2) ........ 20 db m operating case temperature range (t case ) ..................................................... C4 0 c to 85 c storage temperature range .................. C 65 c to 150 c junction temperature (t j ) .................................... 150 c (note 1) 24 23 22 21 20 19 7 8 9 top view 25 gnd uf package 24-lead (4mm 4mm) plastic qfn 10 11 12 6 5 4 3 2 1 13 14 15 16 17 18 dnc dnc dnc dnc dnc dnc out gnd t_diode dnc dnc dnc in gnd v cc dnc dnc dnc dnc gnd v cc dnc dnc dnc t jmax = 150c, v jc = 54c/w exposed pad ( pin 25) is gnd, must be soldered to pcb order information lead free finish tape and reel part marking* package description temperature range ltc6431aiuf-20#pbf ltc6431aiuf-20#trpbf 43120 24-lead (4mm w 4mm) plastic qfn C40c to 85c t case ltc6431biuf-20#pbf ltc6431biuf-20#trpbf 43120 24-lead (4mm w 4mm) plastic qfn C40c to 85c t case consult lt c marketing for parts specified with wider operating temperature ranges. *the temperature grade is identified by a label on the shipping container. consult lt c marketing for information on nonstandard lead based finish parts. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ dc electrical characteristics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c. v cc = 5v, z source = z load = 50. typical measured dc electrical performance using test circuit a. symbol parameter conditions min typ max units v s operating supply range l 4.75 5.0 5.25 v i s(tot) total supply current all v cc pins plus out l 75 68 93 113 129 ma ma i s(out) total supply current to out pin current to out l 55 51 75 95 115 ma ma i cc current to v cc pin either v cc pin may be used l 15 12.5 18 21 21.5 ma ma ltc 6431-20 643120f for more information www.linear.com/ltc6431-20
3 ac electrical characteristics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c (note 3). v cc = 5v, z source = z load = 50 unless otherwise noted. measurements are performed using test circuit a, measuring from 50 sma to 50 without de-embedding (note 4). symbol parameter conditions min typ max units small signal bw C3db bandwidth de-embedded to package (low frequency cutoff = 20mhz) 2000 mhz s 11 input return loss 20mhz to 2000mhz de-embedded to package C10 db s21 forward power gain 50mhz to 1000mhz de-embedded to package 20.8 db s12 reverse isolation 20mhz to 3000mhz de-embedded to package C23 db s22 output return loss 20mhz to 1400mhz de-embedded to package C10 db frequency = 50mhz s21 power gain de-embedded to package 21.1 db oip3 output third-order intercept point p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade 48.2 47.2 dbm dbm im3 third-order intermodulation p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade C92.4 C90.4 dbc dbc hd2 second harmonic distortion p out = 6dbm C53.5 dbc hd3 third harmonic distortion p out = 6dbm C93.6 dbc p1db output 1db compression point 23.5 dbm nf noise figure de-embedded to package 2.6 db frequency = 140mhz s21 power gain de-embedded to package 21.0 db oip3 output third-order intercept point p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade 48.8 47.8 dbm dbm im3 third-order intermodulation p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade C93.6 C91.6 dbc dbc hd2 second harmonic distortion p out = 6dbm C55.8 dbc hd3 third harmonic distortion p out = 6dbm C96.6 dbc p1db output 1db compression point 23.0 dbm nf noise figure de-embedded to package 2.7 db frequency = 240mhz s21 power gain de-embedded to package l 19.4 19.0 21.0 21.4 21.5 db db oip 3 output third-order intercept point p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade 42.2 46.2 45.7 dbm dbm im3 third-order intermodulation p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade C90.4 C87.4 C80.4 dbc dbc hd2 second harmonic distortion p out = 6dbm C50.5 dbc hd3 third harmonic distortion p out = 6dbm C92.5 dbc p1db output 1db compression point 22.0 dbm nf noise figure de-embedded to package 2.6 db ltc 6431-20 643120f for more information www.linear.com/ltc6431-20
4 ac electrical characteristics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c (note 3). v cc = 5v, z source = z load = 50 unless otherwise noted. measurements are performed using test circuit a, measuring from 50 sma to 50 without de-embedding (note 4). symbol parameter conditions min typ max units frequency = 300 mhz s21 power gain de-embedded to package 20.9 db oip3 output third-order intercept point p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade 45.9 44.8 dbm dbm im3 third-order intermodulation p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade C87.8 C85.6 dbc dbc hd2 second harmonic distortion p out = 6dbm C50.5 dbc hd3 third harmonic distortion p out = 6dbm C83.0 dbc p1db output 1db compression point 21.8 dbm nf noise figure de-embedded to package 2.7 db frequency = 380mhz s21 power gain de-embedded to package 20.9 db oip3 output third-order intercept point p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade 45.0 44.0 dbm dbm im3 third-order intermodulation p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade C86.0 C84.0 dbc dbc hd2 second harmonic distortion p out = 6dbm C50.4 dbc hd3 third harmonic distortion p out = 6dbm C77.4 dbc p1db output 1db compression point 21.7 dbc nf noise figure de-embedded to package 2.8 db frequency = 500mhz s21 power gain de-embedded to package 20.8 db oip3 output third-order intercept point p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade 43.9 42.9 dbm dbm im3 third-order intermodulation p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade C83.8 C81.8 dbc dbc hd2 second harmonic distortion p out = 6dbm C47.8 dbc hd3 third harmonic distortion p out = 6dbm C72.6 dbc p1db output 1db compression point 21.8 dbm nf noise figure de-embedded to package 2.9 db frequency = 600mhz s21 power gain de-embedded to package 20.8 db oip3 output third-order intercept point p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade 41.9 40.9 dbm dbm im3 third-order intermodulation p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade C79.8 C77.8 dbc dbc hd2 second harmonic distortion p out = 6dbm C43.7 dbc hd3 third harmonic distortion p out = 6dbm C64.0 dbc p1db output 1db compression point 21.6 dbm nf noise figure de-embedded to package 3.0 db ltc 6431-20 643120f for more information www.linear.com/ltc6431-20
5 note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2: guaranteed by design and characterization. this parameter is not tested. ac electrical characteristics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c (note 3). v cc = 5v, z source = z load = 50 unless otherwise noted. measurements are performed using test circuit a, measuring from 50 sma to 50 without de-embedding (note 4). symbol parameter conditions min typ max units frequency = 700 mhz s21 power gain de-embedded to package 20.8 db oip3 output third-order intercept point p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade 40.7 39.7 dbm dbm im3 third-order intermodulation p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade C77.4 C75.4 dbc dbc hd2 second harmonic distortion p out = 6dbm C42.1 dbc hd3 third harmonic distortion p out = 6dbm C60.7 dbc p1db output 1db compression point 21.4 dbm nf noise figure de-embedded to package 3.2 db frequency = 800mhz s21 power gain de-embedded to package 20.8 db oip3 output third-order intercept point p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade 39.2 38.2 dbm dbm im3 third-order intermodulation p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade C74.4 C72.4 dbc dbc hd2 second harmonic distortion p out = 6dbm C40.5 dbc hd3 third harmonic distortion p out = 6dbm C63.1 dbc p1db output 1db compression point 21.3 dbm nf noise figure de-embedded to package 3.4 db frequency = 900mhz s21 power gain de-embedded to package 20.8 db oip3 output third-order intercept point p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade 38.5 37.5 dbm dbm im3 third-order intermodulation p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade C73.0 C71.0 dbc dbc hd2 second harmonic distortion p out = 6dbm C37.1 dbc hd3 third harmonic distortion p out = 6dbm C60.4 dbc p1db output 1db compression point 21.1 dbm nf noise figure de-embedded to package 3.7 db frequency = 1000mhz s21 power gain de-embedded to package 20.8 db oip3 output third-order intercept point p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade 37.5 36.5 dbm dbm im3 third-order intermodulation p out = 2dbm/tone, ?f = 1mhz, a-grade p out = 2dbm/tone, ?f = 1mhz, b-grade C71.0 C69.0 dbc dbc hd2 second harmonic distortion p out = 6dbm C36.9 dbc hd3 third harmonic distortion p out = 6dbm C55.1 dbc p1db output 1db compression point 20.8 dbc nf noise figure de-embedded to package 3.8 db note 3: the ltc6431-20 is guaranteed functional over the case operating temperature range of C40c to 85c. note 4: small-signal parameters s and noise are de-embedded to the package pins, while large-signal parameters are measured directly from the circuit. ltc 6431-20 643120f for more information www.linear.com/ltc6431-20
6 typical performance characteristics s11 vs frequency over temperature s21 vs frequency over temperature s12 vs frequency over temperature s22 vs frequency over temperature oip3 vs frequency oip3 vs power out over frequency s parameters vs frequency stability factor k vs frequency over temperature nf vs frequency over case temperature t a = 25c, v cc = 5v, z source = z load = 50 unless otherwise noted. measurements are performed using test circuit a, measuring from 50 sma to 50 without de-embedding (note 4). frequency (mhz) 0 ?35 mag (db) ?25 ?15 ?5 5 25 500 1000 1500 2000 643120 g01 2500 3000 15 ?30 ?20 ?10 0 s11 s12 s21 s22 10 20 frequency (mhz) 0 0 stability factor k 1 3 4 5 10 7 1000 2000 643120 g02 2 8 9 6 3000 4000 100c 85c 70c 50c 30c 0c ?20c ?40c t case = frequency (mhz) 0 0 noise figure (db) 1 3 4 5 7 643120 g03 2 6 800 2000 400 1200 1600 85c 25c ?40c t case = frequency (mhz) 0 ?25 mag s11 (db) ?20 ?15 ?10 ?5 0 500 1000 1500 2000 643120 g04 2500 3000 100c 85c 70c 50c 30c 0c ?20c ?40c t case = frequency (mhz) 0 0 mag s21 (db) 5 10 15 20 25 500 1000 1500 2000 643120 g05 2500 3000 100c 85c 70c 50c 30c 0c ?20c ?40c t case = frequency (mhz) 0 mag s12 (db) ?20 643120 g06 ?30 ?40 1000 2000 500 1500 2500 ?10 0 ?25 ?35 ?15 ?5 3000 100c 85c 70c 50c 30c 0c ?20c ?40c t case = frequency (mhz) 0 ?25 mag s22 (db) ?20 ?15 ?10 ?5 0 500 1000 1500 2000 643120 g07 2500 3000 100c 85c 70c 50c 30c 0c ?20c ?40c t case = frequency (mhz) 0 oip3 (dbm) 42 44 46 600 1000 643120 g08 40 38 36 200 v cc = 5v t a = 25c p out = 2dbm/tone f space = 1mhz z in = z out = 50 400 800 48 50 52 rf power out (dbm/tone) ?10 oip3 (dbm) 42 46 50 54 6 643120 g09 38 34 40 44 48 52 36 32 30 ?6 ?2 2 ?8 8 ?4 0 4 10 50mhz 100mhz 200mhz 240mhz 300mhz 400mhz 500mhz 600mhz 700mhz 800mhz 900mhz 1000mhz ltc 6431-20 643120f for more information www.linear.com/ltc6431-20
7 typical performance characteristics hd2 vs frequency over p out hd3 vs input frequency over p out hd4 vs input frequency over p out total current (i tot ) vs v cc total current (i tot ) vs temperature total current vs rf input power oip3 vs frequency over v cc voltage oip3 vs tone spacing over frequency oip3 vs frequency over case temperature t a = 25c, v cc = 5v, z source = z load = 50 unless otherwise noted. measurements are performed using test circuit a, measuring from 50 sma to 50 without de-embedding (note 4). frequency (mhz) 0 34 oip3 (dbm) 36 40 42 44 400 800 1000 52 643120 g10 38 200 600 46 48 50 t a = 25c p out = 2dbm/tone f space = 1mhz z in = z out = 50 4.5v 4.75v 5v 5.25v 5.5v tone spacing (mhz) 0 oip3 (dbm) 42 46 50 40 643120 g11 38 34 40 44 48 36 32 30 10 20 30 5 45 15 25 35 50 50mhz 100mhz 200mhz 240mhz 300mhz 400mhz 500mhz 600mhz 700mhz 800mhz 900mhz 1000mhz frequency (mhz) 0 20 oip3 (dbm) 25 35 40 45 55 100 500 700 643120 g12 30 50 400 900 1000 200 300 600 800 v cc = 5v p out = 2dbm/tone f space = 1mhz z in = z out = 50 85c 70c 50c 28c 0c ?20c ?40c t case = input frequency (mhz) 0 ?70 hd2 (dbc) ?60 ?40 ?30 ?20 0 100 500 700 643120 g13 ?50 ?10 400 900 1000 200 300 600 800 4dbm 6dbm 8dbm 10dbm rf p out = input frequency (mhz) 0 ?110 ?70 ?80 ?90 ?100 hd3 (dbc) ?60 ?40 ?30 ?20 0 100 500 700 643120 g14 ?50 ?10 400 900 1000 200 300 600 800 4dbm 6dbm 8dbm 10dbm rf p out = input frequency (mhz) 0 ?110 ?70 ?80 ?90 ?100 hd4 (dbc) ?60 ?40 ?30 ?20 0 100 500 700 643120 g15 ?50 ?10 400 900 1000 200 300 600 800 4dbm 6dbm 8dbm 10dbm rf p out = v cc (v) 4 i tot (ma) 80 90 100 4.75 5.25 6 643120 g16 70 60 50 4.25 4.5 5 5.5 5.75 t case = 25c temperature (c) ?50 0 i tot (ma) 20 40 60 80 120 ?25 0 25 50 643120 g17 75 100 100 10 30 50 70 110 90 v cc = 5v rf input power (dbm) ?15 total current (ma) 80 90 100 5 643120 g18 70 60 75 85 95 65 55 50 ?10 ?5 0 10 v sup = 5v t a = 25c freq = 200mhz ltc 6431-20 643120f for more information www.linear.com/ltc6431-20
8 pin functions typical performance characteristics output power vs input power over frequency gain vs output power over frequency p1db vs frequency t a = 25c, v cc = 5v, z source = z load = 50 unless otherwise noted. measurements are performed using test circuit a, measuring from 50 sma to 50 without de-embedding (note 4). input power (dbm) ?10 output power (dbm) 16 18 20 6 643120 g19 14 12 8 ?6 ?2 2 ?8 8 ?4 0 4 10 24 22 50mhz 100mhz 200mhz 300mhz 400mhz 500mhz 600mhz 700mhz 800mhz 900mhz 1000mhz output power (dbm) 10 19 20 22 16 20 643120 g20 18 17 12 14 18 22 24 16 15 21 gain (db) 50mhz 100mhz 200mhz 300mhz 400mhz 500mhz 600mhz 700mhz 800mhz 900mhz 1000mhz frequency (mhz) 0 p1db (dbm) 21 23 25 800 643120 g21 19 17 20 22 24 18 16 15 200 400 600 1000 dnc (pins 1 to 7, 10 to 15, 19 to 21): do not connect. do not connect these pins, allow them to float. failure to float these pins may impair operation of the ltc6431-20. gnd (pins 8, 17, 23, exposed pad pin 25): ground. for best rf performance, all ground pins should be connected to the printed circuit board ground plane. the exposed pad (pin 25) should have multiple via holes to an underlying ground plane for low inductance and good thermal dissipation. v cc (pins 9, 22): positive power supply. either or both v cc pins should be connected to the 5.0 v supply. bypass the v cc pin with 1000 pf and 0.1 f capacitors. the 1000pf capacitor should be physically close to pin 22. t_diode (pin 16): optional diode. the t_diode can be forward biased to ground with 1 ma of current. the measured voltage will be an indicator of chip temperature. out (pin 18): amplifier output pin. a choke inductor is necessary to provide power from the 5 v supply and to provide rf isolation. for best performance select a choke with low loss and high self-resonant frequency ( srf). a dc blocking capacitor is also required. see applications information section for specific recommendations. in (pin 24): signal input pin with internally generated 2.0v dc bias . a dc blocking capacitor is required. see applica- tions information section for specific recommendations. ltc 6431-20 643120f for more information www.linear.com/ltc6431-20
9 block diagram test circuit a 24 18 16 20db gain bias and temperature compensation v cc 9, 22 out in gnd 8, 17, 23, 25 (exposed pad) t_diode 643122 bd port input port output 643120 f01 c7 1000pf l1 560nh dnc dnc dnc dnc dnc dnc out gnd t_diode dnc dnc dnc in gnd v cc dnc dnc dnc dnc gnd v cc dnc dnc dnc c6 0.1f c3 1000pf v cc = 5v c1 60pf optional stability network r1 350 c5 1nf ltc6431-20 + + + + + ltc 6431-20 643120f for more information www.linear.com/ltc6431-20
10 operation applications information the ltc6431-20 is a highly linear, fixed-gain amplifier that is configured to operate single ended. its core signal path consists of a single amplifier stage, minimizing stability issues. the input is a darlington pair for high input imped - ance and high current gain. additional circuit enhancements increase the output impedance and minimize the effects of internal miller capacitance. the ltc6431-20 starts with a classic rf gain block to - pology but adds enhancements to dramatically improve linearity. shunt and series feedback are added to lower the input/output impedance and match them simultaneously to the 50 source and load. meanwhile, an internal bias controller optimizes the internal operating point for peak linearity over environmental changes. this circuit archi - tecture provides low noise, excellent rf power handling capability and wide bandwidth characteristics that are desirable for if signal chain applications. the ltc6431-20 is a highly linear fixed gain amplifier which is designed for ease of use. implementing an rf gain stage is often a multi-step project. typically an rf designer must choose a bias point and design a bias network. next we need to address impedance matching with input and output matching networks and finally add stability networks to ensure stable operation in and out of band. these tasks are handled internally within the ltc6431-20. the ltc6431-20 has an internal self-biasing network which compensates for temperature variation and keeps the device biased for optimal linearity. therefore input and output dc blocking capacitors are required. both the input and output are internally impedance matched to 50 from 20 mhz to 1400 mhz. similarly, an rf choke is required at the output to deliver dc current to the de - vice. the rf choke acts as a high impedance (isolation) to the dc supply which is at rf ground. thus, the internal ltc6431-20 impedance matching is unaffected by the biasing network. the open-collector output topology can deliver much more power than an amplifier whose collector is biased through a resistor or active load. choosing the right rf choke not all choke inductors are created equal. it is always important to select an inductor with low r loss , as this will drop the available voltage to the device. also look for an inductor with high self-resonant frequency ( srf) as this will limit the upper frequency where the choke is useful. above the srf, the parasitic capacitance dominates and the choke impedance will drop . for these reasons, wire wound inductors are preferred, and multilayer ceramic chip inductors should be avoided for an rf choke. since the ltc6431-20 is capable of such wideband operation, a single choke value will probably not result in optimized performance across its full frequency band. table 1 lists target frequency bands and suggested corresponding inductor values: table 1. target frequency bands and suggested inductor values frequency band (mhz) inductor value (nh) model number manufacturer 20 to100 1500nh 0603ls coilcraft www.coilcraft.com 100 to 500 560nh 0603ls 500 to1000 100nh 0603ls 1000 to 2000 51nh 0603ls dc blocking capacitor the role of a dc blocking capacitor is straightforward; block the path of dc current and allow a low series impedance path for the ac signal. lower frequencies require a higher value of dc blocking capacitance. generally , 1000 pf to 10000pf will suffice for operation down to 20 mhz. the ltc6431-20 is relatively insensitive to the choice of block - ing capacitor. rf bypass capacitor rf bypass capacitors act to shunt ac signals to ground with a low impedance path. it is best to place them as close as possible to the dc power supply pins of the de - vice. any extra distance translates into additional series inductance which lowers the self-resonant frequency and ltc 6431-20 643120f for more information www.linear.com/ltc6431-20
11 applications information useful bandwidth of the bypass capacitor. the suggested bypass capacitor network consists of two capacitors: a low value 1000 pf capacitor to handle high frequencies in parallel with a larger 0.1 f capacitor to handle lower frequencies. use ceramic capacitors of an appropriate physical size for each capacitance value (e.g., 0402 for the 1000pf and 0805 for the 0.1 f) to minimize the equivalent series resistance (esr) of the capacitor. low frequency stability most rf gain blocks suffer from low frequency instability. to avoid any stability issues, the ltc6431-20 has an internal feedback network that lowers the gain and matches the input and output impedances at frequencies above 20mhz. this feedback network contains a series capacitor so if at some low frequency the feedback fails, the gain increases and gross impedance mismatches occur indeed a recipe for instability. luckily this situation is easily resolved with a parallel capacitor and resistor network on the input as seen in test circuit a. this network provides resistive loss at low frequencies and is bypassed by the parallel capaci - tor within the desired band of operation. however, if the ltc6431-20 is preceded by a low frequency termination, such as a choke, the stability network is not required. t est circuit the test circuit shown in figure 2 is designed to allow evaluation of the ltc6431-20 with standard single-ended 50 test equipment. the circuit requires a minimum of external components. since the ltc6431-20 is a wideband part, the evaluation test circuit is optimized for wideband operation. obviously, for narrowband applications the circuit can be further optimized. as mentioned earlier, input and output dc blocking capacitors are required as this device is internally biased for optimal operation. a frequency appropriate choke and decoupling capacitors are required to provide dc bias to the rf out node. a 5v supply should also be applied to both of the v cc pins on the device. a suggested parallel 60pf, 350 network has been added to the input to ensure low frequency stabil - ity. the 60 pf capacitance can be increased to improve low frequency (<150 mhz) performance. however, the designer needs to be sure that the impedance presented at low frequency will not create instability please note that a number of dnc pins are connected on the demo board. these connections are not necessary for normal circuit operation. exposed pad and ground plane considerations as with any rf device, minimizing ground inductance is critical. care should be taken with board layout using these exposed pad packages. the maximum allowable number of minimum diameter via holes should be placed underneath the exposed pad and connected to as many ground plane layers as possible. this will provide good rf ground and low thermal impedance. maximizing the copper ground plane will also improve heat spreading and lower inductance. it is a good idea to cover the via holes with a solder mask on the back side of the pcb to prevent solder from wicking away from the critical pcb to exposed pad interface. the ltc6431-20 is a wide bandwidth part but it is not intended for operation down to dc. the lower frequency cutoff (20 mhz) is limited by on-chip matching elements. ltc 6431-20 643120f for more information www.linear.com/ltc6431-20
12 demo board 5 5 4 4 3 3 2 2 1 1 d d c c b b a a ???????????????????????????????????? ????????????????????????????? ???????????????????????????????? ??????????????? ?????????????????????????????????????????????? ????? ???? ???? ??? ??? ??? ??? ???????????????? ??????????? ???? ???????? ??? ??? ??????? ????????? ? ???????? ?? ???????????????? ??????????? ???? ???????? ??? ??? ??????? ????????? ? ???????? ?? ???????????????? ??????????? ???? ???????? ??? ??? ??????? ????????? ? ???????? ?? ???? ????? ?????? ???? ????? ?? ?????? ????????? ???????? ???????? technology ?????????????????? ?????????????????? ???????????????????? ??????????????????? ?????????????????????????????????????? ??????????????? ???????????????????????????????????????????????????? ???????????????????????????????????????????????????? ???????????????????????????????????????????????????? ?????????????????????????????????????????????????? ???????????????????????????????????????????????? ????????????????????????????????????????????????????? ??????????????????????????????????????????? ??????????????????????????????????????????????????? ???????????????????????????????????????????????????? ????????? ?????????????????????????????????????????????? ???????????? ?????????????? ? ???????????????????????? ?? ?????????????????? ??? ??????? ??? ?????????? ?????????????????? ???? ????? ?????? ???? ????? ?? ?????? ????????? ???????? ???????? technology ?????????????????? ?????????????????? ???????????????????? ??????????????????? ?????????????????????????????????????? ??????????????? ???????????????????????????????????????????????????? ???????????????????????????????????????????????????? ???????????????????????????????????????????????????? ?????????????????????????????????????????????????? ???????????????????????????????????????????????? ????????????????????????????????????????????????????? ??????????????????????????????????????????? ??????????????????????????????????????????????????? ???????????????????????????????????????????????????? ????????? ?????????????????????????????????????????????? ???????????? ?????????????? ? ???????????????????????? ?? ?????????????????? ??? ??????? ??? ?????????? ?????????????????? ???? ????? ?????? ???? ????? ?? ?????? ????????? ???????? ???????? technology ?????????????????? ?????????????????? ???????????????????? ??????????????????? ?????????????????????????????????????? ??????????????? ???????????????????????????????????????????????????? ???????????????????????????????????????????????????? ???????????????????????????????????????????????????? ?????????????????????????????????????????????????? ???????????????????????????????????????????????? ????????????????????????????????????????????????????? ??????????????????????????????????????????? ??????????????????????????????????????????????????? ???????????????????????????????????????????????????? ????????? ?????????????????????????????????????????????? ???????????? ?????????????? ? ???????????????????????? ?? ?????????????????? ??? ??????? ??? ?????????? ?????????????????? ?? ??? ?? ??? ??? ??? ?? ?? ?? ?????? ???? ?? ?????? ???? ?? ????? ???? ?? ????? ???? ?? ??? ?? ??? ?? ??? ?? ??? ?? ?? ?? ? ?? ? ??? ??? ?? ?? ?? ?????? ?? ?????? ?? ??????? ?? ??????? ??? ??? ?? ?? ??? ??? ?? ?????????? ?? ?????????? ??? ? ??? ?? ??? ? ?? ?? ??? ? ??? ? ??? ? ??? ?? ??? ?? ??? ?? ??? ?? ??? ?? ??? ?? ??? ?? ??????? ?? ??? ? ??? ? ??? ? ??? ?? ??? ?? ??? ?? ??? ?? ??? ? ??? ?? ??? ?? ??? ??? ?? ?? ?? ?? ?? ?????? ?? ?????? ??? ??? ?? ????? ?? ????? ?? ?? ?? ??? ?? ??? ?? ???? ?? ???? ?? ?????? ???? ?? ?????? ???? ?? ??? ?? ??? ?? ?? ?? ??? ?? ??? ?? ?????? ???? ?? ?????? ???? figure 2. dc2077a demo board schematic figure 3. demo board ltc 6431-20 643120f for more information www.linear.com/ltc6431-20
13 s parameters frequency (mhz) s11 (mag) s 11 (ph) s21 (mag) s21 (ph) s12 (mag) s12 (ph) s22 (mag) s22 (ph) gtu (max) stabilit y (k) 15 C12.34 C134.00 21.65 166.01 C23.63 9.07 C14.61 C124.25 22.07 0.92 60 C14.04 C170.60 21.09 171.15 C23.46 C1.42 C18.21 C175.38 21.33 0.98 105 C14.03 C179.35 21.03 168.79 C23.49 C5.14 C18.66 166.03 21.26 0.98 150 C14.08 175.80 21.01 165.71 C23.53 C8.75 C18.62 154.22 21.24 0.98 195 C14.07 172.39 20.98 162.19 C23.53 C11.98 C18.41 143.47 21.22 0.98 240 C14.15 167.78 20.98 158.68 C23.51 C14.70 C18.30 133.71 21.22 0.98 285 C14.28 163.28 20.94 155.06 C23.57 C17.52 C18.41 123.42 21.17 0.99 330 C14.39 160.26 20.90 151.22 C23.56 C20.65 C18.26 114.75 21.13 0.99 375 C14.29 156.48 20.86 147.90 C23.60 C23.49 C18.15 108.36 21.09 0.99 420 C14.21 153.43 20.83 144.33 C23.66 C26.30 C17.84 100.90 21.07 0.99 465 C14.16 149.55 20.84 140.79 C23.66 C28.96 C17.57 92.84 21.09 0.99 510 C14.23 146.15 20.81 137.22 C23.73 C31.97 C17.39 84.51 21.06 0.99 555 C14.33 141.99 20.83 133.57 C23.74 C34.94 C17.34 77.29 21.07 0.99 600 C14.44 138.03 20.82 129.91 C23.76 C37.66 C17.19 68.45 21.06 0.99 645 C14.54 132.96 20.83 126.20 C23.82 C40.56 C17.18 61.23 21.06 1.00 690 C14.61 129.14 20.82 122.55 C23.82 C43.37 C16.95 51.45 21.06 1.00 735 C14.72 125.47 20.81 118.75 C23.88 C46.23 C16.82 43.84 21.05 1.00 780 C14.82 121.92 20.83 115.24 C23.90 C49.23 C16.71 35.20 21.07 1.00 825 C15.09 117.58 20.82 111.33 C23.92 C51.95 C16.62 26.73 21.05 1.00 870 C15.49 113.60 20.86 107.36 C23.98 C55.23 C16.57 16.50 21.08 1.00 915 C15.70 109.88 20.85 103.72 C23.99 C58.08 C16.46 6.76 21.07 1.01 960 C16.07 106.95 20.87 99.43 C24.11 C61.03 C16.09 C3.10 21.08 1.01 1005 C16.34 104.03 20.83 95.71 C24.09 C64.35 C15.67 C12.60 21.05 1.01 1050 C16.85 102.41 20.87 91.50 C24.18 C67.08 C15.20 C21.77 21.10 1.01 1095 C17.27 100.19 20.86 87.64 C24.20 C70.22 C14.69 C31.60 21.09 1.01 1140 C17.95 98.62 20.82 82.93 C24.28 C73.37 C14.08 C40.57 21.06 1.01 1185 C18.45 97.87 20.83 79.39 C24.34 C76.81 C13.51 C48.89 21.09 1.01 1230 C19.02 98.94 20.77 74.51 C24.42 C79.94 C12.81 C57.15 21.06 1.02 1275 C19.50 101.29 20.79 70.33 C24.49 C83.51 C12.18 C65.26 21.11 1.01 1320 C19.85 104.33 20.60 65.52 C24.57 C86.55 C11.49 C72.53 20.96 1.02 1365 C20.08 106.87 20.62 61.84 C24.67 C90.04 C11.02 C79.96 21.02 1.01 1410 C19.95 109.72 20.45 57.31 C24.78 C93.19 C10.42 C87.02 20.91 1.01 1455 C19.77 113.75 20.46 52.82 C24.90 C96.97 C9.99 C93.77 20.97 1.01 1500 C19.51 117.49 20.24 48.67 C25.03 C100.45 C9.41 C100.97 20.82 1.01 1545 C18.89 119.17 20.18 44.22 C25.18 C103.92 C8.92 C108.10 20.83 1.01 1590 C18.24 119.82 19.98 40.21 C25.35 C107.23 C8.50 C114.08 20.71 1.01 1635 C17.42 119.84 19.95 35.90 C25.53 C111.01 C8.07 C120.18 20.76 1.00 1680 C16.67 117.91 19.72 31.69 C25.69 C113.96 C7.78 C126.41 20.60 1.00 1725 C15.83 117.38 19.66 27.35 C25.93 C118.14 C7.51 C132.99 20.63 1.00 1770 C15.05 116.13 19.36 23.32 C26.10 C121.42 C7.13 C139.50 20.44 1.00 1815 C14.19 114.01 19.28 18.99 C26.43 C124.76 C6.90 C145.49 20.45 1.00 1860 C13.50 111.51 18.90 15.44 C26.53 C128.07 C6.72 C151.16 20.14 1.02 1905 C12.85 109.19 19.01 11.94 C26.93 C131.53 C6.58 C157.57 20.31 1.02 1950 C12.24 106.89 18.52 6.50 C27.03 C135.18 C6.51 C164.06 19.89 1.04 1995 C11.67 104.26 18.70 3.97 C27.55 C137.80 C6.39 C170.92 20.14 1.05 5v, 95ma, z = 50, t a = 25c de-embedded to package pins ltc 6431-20 643120f for more information www.linear.com/ltc6431-20
14 s parameters 5v, 95ma, z = 50, t a = 25c de-embedded to package pins frequency (mhz) s11 (mag) s 11 (ph) s21 (mag) s21 (ph) s12 (mag) s12 (ph) s22 (mag) s22 (ph) gtu (max) stabilit y (k) 2040 C11.14 100.90 17.88 -0.72 C27.55 C142.12 C6.26 C177.67 19.40 1.10 2085 C10.64 97.70 18.36 -5.52 C28.08 C143.56 C6.12 176.54 19.97 1.08 2130 C10.00 94.35 17.25 -6.06 C28.25 C150.27 C6.05 170.42 18.94 1.18 2175 C9.61 91.25 17.78 -14.20 C28.58 C149.92 C6.02 163.95 19.53 1.14 2220 C9.17 88.10 17.05 -12.16 C29.10 C156.51 C5.98 156.51 18.87 1.27 2265 C8.83 84.64 16.93 -20.90 C29.21 C157.46 C5.82 149.75 18.85 1.26 2310 C8.46 81.25 16.78 -18.18 C29.86 C162.26 C5.78 143.79 18.78 1.34 2355 C8.16 77.66 16.61 -27.54 C29.98 C162.93 C5.73 137.46 18.68 1.35 2400 C7.83 74.62 16.50 -25.19 C30.69 C167.63 C5.69 131.27 18.64 1.45 2445 C7.53 71.16 16.06 -34.94 C30.51 C168.53 C5.62 125.41 18.30 1.45 2490 C7.27 68.07 16.20 -31.94 C31.57 C172.15 C5.67 118.93 18.47 1.60 2535 C6.92 64.84 15.35 -40.99 C31.02 C175.82 C5.56 113.08 17.75 1.59 2580 C6.70 61.73 16.03 -39.80 C32.38 C175.70 C5.57 107.60 18.49 1.70 2625 C6.41 58.18 14.68 -45.37 C32.09 176.58 C5.50 101.45 17.24 1.87 2670 C6.27 55.57 15.67 -47.21 C32.97 179.37 C5.63 95.57 18.23 1.85 2715 C6.03 52.10 14.17 -49.38 C32.98 169.92 C5.56 90.99 16.82 2.16 2760 C5.89 49.48 15.57 -53.97 C33.09 175.85 C5.27 85.87 18.39 1.75 2805 C5.67 45.63 13.93 -53.77 C34.22 163.49 C5.21 80.99 16.86 2.40 2850 C5.50 42.67 15.09 -63.32 C33.44 166.56 C5.17 75.72 18.10 1.84 2895 C5.46 39.67 13.89 -58.19 C35.33 159.61 C5.18 70.71 16.91 2.69 2940 C5.30 36.08 14.37 -72.34 C34.24 156.24 C5.09 65.83 17.50 2.14 2985 C5.19 33.25 13.99 -65.16 C35.94 156.17 C5.09 61.31 17.17 2.74 3030 C5.01 30.47 13.73 -77.37 C35.59 148.57 C4.97 56.55 17.04 2.62 3075 C4.92 27.89 13.65 -74.73 C36.56 148.06 C4.90 53.19 17.03 2.92 3120 C4.91 24.65 13.20 -83.66 C36.86 137.09 C4.91 49.53 16.59 3.20 3165 C4.82 22.03 13.19 -82.28 C37.44 140.21 C4.93 45.90 16.61 3.42 3210 C4.75 18.92 12.70 -90.39 C38.12 129.33 C4.92 41.35 16.17 3.90 3255 C4.68 16.03 12.57 -89.72 C38.72 129.83 C4.86 37.27 16.09 4.20 3300 C4.59 13.26 12.24 -97.59 C39.34 121.95 C4.83 33.29 15.82 4.64 3345 C4.55 10.73 11.84 -98.06 C39.73 119.68 C4.77 29.79 15.48 5.05 3390 C4.56 8.20 11.62 -103.89 C40.66 109.67 C4.74 27.13 15.26 5.79 3435 C4.51 5.01 10.89 -101.79 C41.66 111.26 C4.81 24.06 14.53 7.15 3480 C4.45 2.35 11.06 -111.51 C43.12 101.22 C4.88 20.14 14.70 8.34 3525 C4.43 C0.44 10.16 -107.21 C42.93 99.02 C4.93 15.63 13.79 9.10 3570 C4.41 C2.83 9.99 -117.04 C45.97 89.65 C4.84 11.54 13.68 13.14 3615 C4.40 C5.71 9.68 -110.63 C44.49 84.10 C4.90 8.34 13.33 11.53 3660 C4.38 C8.39 8.93 -121.14 C47.04 75.52 C5.05 3.84 12.53 17.24 3705 C4.34 C11.28 9.26 -114.41 C46.78 68.74 C5.08 C0.41 12.86 16.05 3750 C4.29 C13.61 8.25 -123.30 C48.84 61.49 C5.19 C4.64 11.84 23.09 3795 C4.26 C16.54 8.99 -119.02 C48.49 43.03 C5.23 C10.04 12.58 20.33 3840 C4.23 C18.89 7.52 -126.22 C50.09 36.00 C5.24 C14.83 11.12 29.00 3885 C4.21 C21.65 8.40 -125.79 C51.80 18.74 C5.26 C19.77 12.01 31.89 3930 C4.20 C23.89 7.12 -125.77 C50.77 12.06 C5.34 C24.50 10.70 33.05 3975 C4.15 C26.81 7.91 -131.37 C50.96 2.88 C5.43 C30.21 11.49 30.86 4020 C4.11 C29.36 6.95 -128.17 C49.54 C0.70 C5.41 C36.65 10.56 29.01 ltc 6431-20 643120f for more information www.linear.com/ltc6431-20
15 information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. package description please refer to http://www .linear.com/designtools/packaging/ for the most recent package drawings. 4.00 0.10 (4 sides) note: 1. drawing proposed to be made a jedec package outline mo-220 variation (wggd-x)?to be approved 2. drawing not to scale 3. all dimensions are in millimeters 4. dimensions of exposed pad on bottom of package do not include mold flash. mold flash, if present, shall not exceed 0.15mm on any side, if present 5. exposed pad shall be solder plated 6. shaded area is only a reference for pin 1 location on the top and bottom of package pin 1 top mark (note 6) 0.40 0.10 2423 1 2 bottom view?exposed pad 2.45 0.10 (4-sides) 0.75 0.05 r = 0.115 typ 0.25 0.05 0.50 bsc 0.200 ref 0.00 ? 0.05 (uf24) qfn 0105 rev b recommended solder pad pitch and dimensions 0.70 0.05 0.25 0.05 0.50 bsc 2.45 0.05 (4 sides) 3.10 0.05 4.50 0.05 package outline pin 1 notch r = 0.20 typ or 0.35 45 chamfer uf package 24-lead plastic qfn (4mm 4mm) (reference ltc dwg # 05-08-1697 rev b) ltc 6431-20 643120f for more information www.linear.com/ltc6431-20
16 ? linear technology corporation 2014 lt 0314 ? printed in usa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com/ltc6431-20 related parts typical application 643120 ta02 ltc6431-20 r source 50 v cc = 5v c = 1000pf 1000pf 9, 22 8, 17, 23, 25 24 18 5v r f choke, l = 560nh r load 50 0.1f c =1000pf part number description comments fixed gain if amplifiers/adc drivers ltc6431-15 15db gain 50 gain block if amplifier single ended oip3 = 47dbm at 240mhz, 20mhz to 1700mhz bandwidth, 3.3db nf ltc 6430-15 15db gain block if amplifier differential oip3 = 50dbm at 240mhz, 20mhz to 1700mhz bandwidth, 3.3db nf ltc 6417 1.6ghz low noise high linearity differential buffer/adc driver oip 3 = 41dbm at 300mhz, can drive 50 differential output, high speed v oltage clamping protects subsequent circuitry ltc6416 2ghz, 16-bit differential adc buffer C72dbc im2 at 300mhz 2v p-p composite, i s = 42ma, e n = 2.8nv/hz, a v = 0db, 300mhz ltc6410-6 1.4ghz differential if amplifier with configurable input impedance oip 3 = 36dbm at 70mhz, flexible inter face-to-mixer if port ltc6400-8/ltc6400-14/ ltc6400-20/ltc6400-26 1.8ghz low noise, low distortion differential adc drivers C71 dbc im3 at 240mhz 2v p-p composite, i s = 90ma, a v = 8db, 14db, 20db, 26db ltc2420-20 dual 1.8ghz low noise, low distortion differential adc drivers dual version of the ltc6400-20, a v = 20db variable gain if amplifiers/adc drivers ltc6412 800mhz, 31db range analog-controlled vga oip3 = 35dbm at 240mhz, continuously-adjustable gain control baseband differential amplifiers ltc6409 1.1nvhz single supply differential amplifier/adc driver 88db sfdr at 100mhz, ac- or dc-coupled inputs lt 6411 low power differential adc driver/dual selectable gain amplifier C83dbc im3 at 70mhz 2v p-p composite, a v = 1, C1 or 2, 16ma, excellent for single-ended to differential conversion ltc6406 3ghz rail-to-rail input differential amplifier/ adc driver C65dbc im3 at 50mhz 2v p-p composite, rail-to-rail inputs, e n = 1.6nv/hz, 18ma ltc6404-1/ltc6404-2 low noise rail-to-rail output differential amplifier/ adc driver 16-bit snr, sfdr at 10mhz, rail-to-rail outputs, e n = 1.5nv/hz, ltc6404-1 is unity-gain stable, ltc6404-2 is gain-of-2 stable ltc6403-1 low noise rail-to-rail output differential amplifier/ adc driver 16-bit snr, sfdr at 3mhz, rail-to-rail outputs, e n = 2.8nv/hz high speed adcs ltc2208/ltc2209 16-bit, 130msps/160msps adcs 74.0dbfs noise floor, sfdr > 89db at 140mhz, 2.25v p-p input ltc2259-16 16-bit, 80msps 1.8v adc 72.0dbfs noise floor, sfdr > 82db at 140mhz, 2.00v p-p input ltc2160-16/ltc2161-16/ ltc2162-16 16-bit, 25msps/40msps/60msps adc low power 77dbfs noise floor, sfdr > 84db at 140mhz, 2.00v p-p input ltc2155-14/ltc2156-14/ ltc2157-14/ltc2158-14 14-bit, 170msps/210msps/250msps/310msps adc 2-channel 69dbfs noise floor, sfdr > 80db at 140mhz, 1.50v p-p input, >1ghz input bw ltc2216 16-bit, 80msps adc 79dbfs noise floor, sfdr > 91db at 140mhz, 75v p-p input ltc 6431-20 643120f for more information www.linear.com/ltc6431-20

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