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lt1993-2 1 19932fa 800mhz low distortion, low noise differential ampli er/ adc driver (a v = 2v/v) the lt ? 1993-2 is a low distortion, low noise differential ampli? er/adc driver for use in applications from dc to 800mhz. the lt1993-2 has been designed for ease of use, with minimal support circuitry required. exception- ally low input-referred noise and low distortion products (with either single-ended or differential inputs) make the lt1993-2 an excellent solution for driving high speed 12- bit and 14-bit adcs. in addition to the normal un? ltered outputs (+out and Cout), the lt1993-2 has a built-in 175mhz differential low pass ? lter and an additional pair of ? ltered outputs (+outfiltered, Coutfiltered) to reduce external ? ltering components when driving high speed adcs. the output common mode voltage is easily set via the v ocm pin, eliminating either an output transformer or ac-coupling capacitors in many applications. the lt1993-2 is designed to meet the demanding require- ments of communications transceiver applications. it can be used as a differential adc driver, a general-purpose differential gain block, or in any other application requir- ing differential drive. the lt1993-2 can be used in data acquisition systems required to function at frequencies down to dc. the lt1993-2 operates on a 5v supply and consumes 100ma. it comes in a compact 16-lead 3 3 qfn package and operates over a C40c to 85c temperature range. differential adc driver for: imaging communications differential driver/receiver single ended to differential conversion differential to single ended conversion level shifting if sampling receivers saw filter interfacing/buffering 800mhz C3db bandwidth fixed gain of 2v/v (6db) low distortion: 38dbm oip3, C70dbc hd3 (70mhz, 2v p-p ) 51dbm oip3, C94dbc hd3 (10mhz, 2v p-p ) low noise: 12.3db nf, e n = 3.8nv/hz (70mhz) differential inputs and outputs additional filtered outputs adjustable output common mode voltage dc- or ac-coupled operation minimal support circuitry required small 0.75mm tall 16-lead 3 3 qfn package 4-channel wcdma receive channel applicatio s u features descriptio u typical applicatio u , ltc and lt are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. 2.2v 19932 ta01a mini-circuits tcm4-19 1:4 z-ratio ltc2255 125msps 14-bit adc sampling at 92.16msps 70mhz if in 52.3pf 82nh 0.1 f 0.1 f 12.2 ? lt1993-2 ?ina ?inb ?outfiltered ?out +outfiltered +out +inb+ina v ocm enable 12.2 ? ltc2255 adc ain?ain+ frequency (mhz) 0 amplitude (dbfs) 0 ?20?40 ?80 ?60 ?100 ?10?30 ?50 ?90 ?70 ?110?120 19932 ta01b 15 10 52 0 2 5 45 30 35 40 32768 point ffttone center frequencies at 62.5mhz, 67.5mhz, 72.5mhz, 77.5mhz 4-tone wcdma waveform, lt1993-2 driving ltc2255 14-bit adc at 92.16msps downloaded from: http:///
lt1993-2 2 19932fa total supply voltage (v cca /v ccb /v ccc to v eea /v eeb /v eec ) ...................................................5.5v input current (+ina, Cina, +inb, Cinb, v ocm , enable) ................................................10ma output current (continuous) (note 6) +out, Cout (dc) ..........................................100ma (ac) ..........................................100ma +outfiltered, Coutfiltered (dc) .............15ma (ac) .............45ma output short circuit duration (note 2) ............ inde? nite operating temperature range (note 3) ... C40c to 85c speci? ed temperature range (note 4) .... C40c to 85c storage temperature range ................... C65c to 125c junction temperature ........................................... 125c lead temperature range (soldering 10 sec) ........ 300c (note 1) the denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c. v cca = v ccb = v ccc = 5v, v eea = v eeb = v eec = 0v, enable = 0.8v, +ina shorted to +inb (+in), Cina shorted to Cinb (Cin), v ocm = 2.2v, input common mode voltage = 2.2v, no r load unless otherwise noted. symbol parameter conditions min typ max units input/output characteristics (+ina, +inb, Cina, Cinb, +out, Cout, +outfiltered, Coutfiltered) gdiff gain differential (+out, Cout), v in = 0.8v differential 5.8 6.08 6.3 db v swingmin single-ended +out, Cout, +outfiltered, Coutfiltered. v in = 2.2v differential 0.25 0.35 0.5 vv v swingmax single-ended +out, Cout, +outfiltered, Coutfiltered. v in = 2.2v differential 3.63.5 3.75 v v v swingdiff output voltage swing differential (+out, Cout), v in = 2.2v differential 6.5 6 7v p-p v p-p i out output current drive (note 5) 40 45 ma v os input offset voltage C6.5 C10 1 6.5 10 mvmv tcv os input offset voltage drift t min to t max 2.5 v/c i vrmin input voltage range, min single-ended C0.1 v i vrmax input voltage range, max single-ended 5.1 v r indiff differential input resistance 170 200 240 c indiff differential input capacitance 1p f cmrr common mode rejection ratio input common mode C0.1v to 5.1v 45 70 db absolute axi u rati gs w ww u package/order i for atio uu w dc electrical characteristics 16 15 14 13 5 6 7 8 top view ud package 16-lead (3mm 3mm) plastic qfn 9 10 17 11 12 4 3 2 1 v ccc v ocm v cca v eea v eec enablev ccb v eeb +ina+inb ?ina ?inb +out +outfiltered?outfiltered ?out t jmax = 125c, ja = 68c/w, jc = 4.2c/w exposed pad is v ee (pin 17) must be soldered to the pcb order part number ud part marking* LT1993CUD-2 lt1993iud-2 lbjg order options tape and reel: add #tr lead free: add #pbf lead free tape and reel: add #trpbf lead free part marking: http://www.linear.com/leadfree/ consult ltc marketing for parts speci? ed with wider operating temperature ranges. *the temperature grade is identi? ed by a label on the shipping container. downloaded from: http:///
lt1993-2 3 19932fa symbol parameter conditions min typ max units input/output characteristics C3dbbw C3db bandwidth 200mv p-p differential (+out, Cout) 500 800 mhz 0.1dbbw bandwidth for 0.1db flatness 200mv p-p differential (+out, Cout) 50 mhz 0.5dbbw bandwidth for 0.5db flatness 200mv p-p differential (+out, Cout) 100 mhz sr slew rate 3.2v p-p differential (+out, Cout) 1100 v/s t s1% 1% settling time 1% settling for a 1v p-p differential step (+out, Cout) 4n s t on turn-on time 40 ns t off turn-off time 250 ns common mode voltage control (v ocm pin) C3dbbw cm common mode small-signal C3db bandwidth 0.1v p-p at v ocm , measured single-ended at +out and Cout 300 mhz sr cm common mode slew rate 1.3v to 3.4v step at v ocm 500 v/s symbol parameter conditions min typ max units r outdiff output resistance 0.3 c outdiff output capacitance 0.8 pf common mode voltage control (v ocm pin) gcm common mode gain differential (+out, Cout), v ocm = 1.1v to 3.6v differential (+out, Cout), v ocm = 1.3v to 3.4v 0.90.9 11 . 1 1.1 v/vv/v v ocmmin output common mode voltage adjustment range, min measured single-ended at +out and Cout 1.11.3 vv v ocmmax output common mode voltage adjustment range, max measured single-ended at +out and Cout 3.63.4 vv v oscm output common mode offset voltage measured from v ocm to average of +out and Cout C30 4 30 mv i biascm v ocm input bias current 51 5 a r incm v ocm input resistance 0.8 3 m c incm v ocm input capacitance 1p f enable pinv il enable input low voltage 0.8 v v ih enable input high voltage 2v i il enable input low current enable = 0.8v 0.5 a i ih enable input high current enable = 2v 13 a power supplyv s operating range 455 . 5 v i s supply current enable = 0.8v 88 100 112 ma i sdisabled supply current (disabled) enable = 2v 250 500 a psrr power supply rejection ratio 4v to 5.5v 55 90 db the denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c. v cca = v ccb = v ccc = 5v, v eea = v eeb = v eec = 0v, enable = 0.8v, +ina shorted to +inb (+in), Cina shorted to Cinb (Cin), v ocm = 2.2v, input common mode voltage = 2.2v, no r load unless otherwise noted. t a = 25c, v cca = v ccb = v ccc = 5v, v eea = v eeb = v eec = 0v, enable = 0.8v, +ina shorted to +inb (+in), Cina shorted to Cinb (Cin), v ocm = 2.2v, input common mode voltage = 2.2v, no r load unless otherwise noted. dc electrical characteristics ac electrical characteristics downloaded from: http:///
lt1993-2 4 19932fa symbol parameter conditions min typ max units noise/harmonic performance input/output characteristics1khz signal second/third harmonic distortion 2v p-p differential (+outfiltered, Coutfiltered) C100 dbc 2v p-p differential (+out, Cout) C100 dbc 2v p-p differential (+out, Cout), r l = 100 C100 dbc 3.2v p-p differential (+outfiltered, Coutfiltered) C91 dbc 3.2v p-p differential (+out, Cout) C91 dbc 3.2v p-p differential (+out, Cout), r l = 100 C91 dbc third-order imd 2v p-p differential composite (+outfiltered, Coutfiltered), f1 = 0.95khz, f2 = 1.05khz C102 dbc 2v p-p differential composite (+out, Cout), r l = 100 , f1 = 0.95khz, f2 = 1.05khz C102 dbc 3.2v p-p differential composite (+outfiltered, Coutfiltered), f1 = 0.95khz, f2 = 1.05khz C93 dbc oip3 1k output third-order intercept differential (+outfiltered, Coutfiltered), f1 = 0.95khz, f2 = 1.05khz 54 dbm e n1k input referred noise voltage density 3.5 nv/hz 1db compression point r l = 100 22.7 dbm 10mhz signal second/third harmonic distortion 2v p-p differential (+outfiltered, Coutfiltered) C94 dbc 2v p-p differential (+out, Cout) C94 dbc 2v p-p differential (+out, Cout), r l = 100 C86 dbc 3.2v p-p differential (+outfiltered, Coutfiltered) C85 dbc 3.2v p-p differential (+out, Cout) C85 dbc 3.2v p-p differential (+out, Cout), r l = 100 C77 dbc third-order imd 2v p-p differential composite (+outfiltered, Coutfiltered), f1 = 9.5mhz, f2 = 10.5mhz C96 dbc 2v p-p differential composite (+out, Cout), r l = 100 , f1 = 9.5mhz, f2 = 10.5mhz C96 dbc 3.2v p-p differential composite (+outfiltered, Coutfiltered), f1 = 9.5mhz, f2 = 10.5mhz C87 dbc oip3 10m output third-order intercept differential (+outfiltered, Coutfiltered), f1 = 9.5mhz, f2 = 10.5mhz 51 dbm nf noise figure measured using dc800a demo board 11.3 db e n10m input referred noise voltage density 3.5 nv/hz 1db compression point r l = 100 22.6 dbm 50mhz signal second/third harmonic distortion 2v p-p differential (+outfiltered, Coutfiltered) C77 dbc 2v p-p differential (+out, Cout) C77 dbc 2v p-p differential (+out, Cout), r l = 100 C74 dbc 3.2v p-p differential (+outfiltered, Coutfiltered) C68 dbc 3.2v p-p differential (+out, Cout) C65 dbc t a = 25c, v cca = v ccb = v ccc = 5v, v eea = v eeb = v eec = 0v, enable = 0.8v, +ina shorted to +inb (+in), Cina shorted to Cinb (Cin), v ocm = 2.2v, input common mode voltage = 2.2v, no r load unless otherwise noted. ac electrical characteristics downloaded from: http:///
lt1993-2 5 19932fa note 1: absolute maximum ratings are those values beyond which the life of a device may be impaired.note 2: as long as output current and junction temperature are kept below the absolute maximum ratings, no damage to the part will occur. note 3: the lt1993c-2 is guaranteed functional over the operating temperature range of C40c to 85c.note 4: the lt1993c-2 is guaranteed to meet speci? ed performance from 0c to 70c. it is designed, characterized and expected to meet speci? ed performance from C40c and 85c but is not tested or qa sampled at these temperatures. the lt1993i-2 is guaranteed to meet speci? ed performance from C40c to 85c. note 5: this parameter is pulse tested. note 6: this parameter is guaranteed to meet speci? ed performance through design and characterization. it has not been tested. symbol parameter conditions min typ max units 3.2v p-p differential (+out, Cout), r l = 100 C65 dbc third-order imd 2v p-p differential composite (+outfiltered, Coutfiltered), f1 = 49.5mhz, f2 = 50.5mhz C84 dbc 2v p-p differential composite (+out, Cout), r l = 100 , f1 = 49.5mhz, f2 = 50.5mhz C88 dbc 3.2v p-p differential composite (+outfiltered, Coutfiltered), f1 = 49.5mhz, f2 = 50.5mhz C75 dbc oip3 50m output third-order intercept differential (+outfiltered, Coutfiltered), f1 = 49.5mhz, f2 = 50.5mhz 45 dbm nf noise figure measured using dc800a demo board 11.8 db e n50m input referred noise voltage density 3.65 nv/hz 1db compression point r l = 100 19.7 dbm 70mhz signal second/third harmonic distortion 2v p-p differential (+outfiltered, Coutfiltered) C70 dbc 2v p-p differential (+out, Cout) C61 dbc 2v p-p differential (+out, Cout), r l = 100 C61 dbc third-order imd 2v p-p differential composite (+outfiltered, Coutfiltered), f1 = 69.5mhz, f2 = 70.5mhz C70 dbc 2v p-p differential composite (+out, Cout), r l = 100 , f1 = 69.5mhz, f2 = 70.5mhz C72 dbc oip3 70m output third-order intercept differential (+outfiltered, Coutfiltered), f1 = 69.5mhz, f2 = 70.5mhz 38 dbm nf noise figure measured using dc800a demo board 12.3 db e n70m input referred noise voltage density 3.8 nv/hz 1db compression point r l = 100 18.5 dbm 100mhz signal second/third harmonic distortion 2v p-p differential (+outfiltered, Coutfiltered) C56 dbc 2v p-p differential (+out, Cout) C54 dbc 2v p-p differential (+out, Cout), r l = 100 C51 dbc third-order imd 2v p-p differential composite (+outfiltered, Coutfiltered), f1 = 99.5mhz, f2 = 100.5mhz C58 dbc 2v p-p differential composite (+out, Cout), r l = 100 , f1 = 99.5mhz, f2 = 100.5mhz C59 dbc oip3 100m output third-order intercept differential (+outfiltered, Coutfiltered), f1 = 99.5mhz, f2 = 100.5mhz 32 dbm nf noise figure measured using dc800a demo board 12.8 db e n100m input referred noise voltage density 4.1 nv/hz 1db compression point r l = 100 17.8 dbm t a = 25c, v cca = v ccb = v ccc = 5v, v eea = v eeb = v eec = 0v, enable = 0.8v, +ina shorted to +inb (+in), Cina shorted to Cinb (Cin), v ocm = 2.2v, input common mode voltage = 2.2v, no r load unless otherwise noted. ac electrical characteristics downloaded from: http:///
lt1993-2 6 19932fa frequency (mhz) 0 output ip3 (dbm) 6055 50 40 4535 30 25 20 19932 g08 60 40 20 80 100 140 120 2 tones, 2v p-p composite 1mhz tone spacing unfiltered outputs filtered outputs frequency (mhz) 0 output ip3 (dbm) 6055 50 40 4535 30 25 20 19932 g09 60 40 20 80 100 140 120 2 tones, 2v p-p composite 1mhz tone spacing unfiltered outputs filtered outputs frequency (mhz) 0 output ip3 (dbm) 6055 50 40 4535 30 25 20 19932 g07 60 40 20 80 100 140 120 2 tones, 2v p-p composite 1mhz tone spacing unfiltered outputs filtered outputs frequency (mhz) 0 third order imd (dbc) ?10?20 ?30 ?50 ?40?60 ?70 ?80 ?90 ?100?110 19932 g06 60 40 20 80 100 140 120 2 tones, 2v p-p composite 1mhz tone spacing unfiltered outputs filtered outputs frequency (mhz) 0 third order imd (dbc) ?10?20 ?30 ?50 ?40?60 ?70 ?80 ?90 ?100?110 19932 g04 60 40 20 80 100 140 120 unfiltered outputs filtered outputs 2 tones, 2v p-p composite 1mhz tone spacing frequency (mhz) gain (db) 2118 15 12 96 3 0 ?3 1 100 1000 10000 19932 g03 10 v in = 100mv p-p unfiltered outputs 10pf 5pf 2pf 0pf frequency (mhz) gain (db) 12 96 3 0 ?3?6 ?9 ?12 1 100 1000 10000 19932 g01 10 v in = 100mv p-p unfiltered: r load = 400 ? filtered: r load = 350 ? (external) + 50 ? (internal, filtered outputs) unfiltered outputs filtered outputs frequency (mhz) gain (db) 12 96 3 0 ?3?6 ?9 ?12 1 100 1000 10000 19932 g02 10 v in = 100mv p-p unfiltered: r load = 100 ? filtered: r load = 50 ? (external) + 50 ? (internal, filtered outputs) unfiltered outputs filtered outputs frequency (mhz) 0 third order imd (dbc) ?10?20 ?30 ?50 ?40?60 ?70 ?80 ?90 ?100?110 19932 g05 60 40 20 80 100 140 120 2 tones, 2v p-p composite 1mhz tone spacing unfiltered outputs filtered outputs frequency response r load = 400 frequency response r load = 100 frequency response vs c load , r load = 400 third order intermodulation distortion vs frequency differential input, no r load third order intermodulation distortion vs frequency differential input, r load = 400 third order intermodulation distortion vs frequency differential input, r load = 100 output third order intercept vs frequency, differential input, no r load output third order intercept vs frequency, differential input, r load = 400 output third order intercept vs frequency, differential input, r load = 100 typical perfor a ce characteristics uw downloaded from: http:///
lt1993-2 7 19932fa output amplitude (dbm) ?1 distortion (dbc) ?50?55 ?60 ?70 ?65?75 ?80 ?85 ?90 ?95 ?100 19932 g18 5 3 17 9 11 hd3 unfiltered outputs hd2 unfiltered outputs hd2 filtered outputs hd3 filtered outputs output amplitude (dbm) ?1 distortion (dbc) ?50?55 ?60 ?70 ?65?75 ?80 ?85 ?90 ?95 ?100 19932 g16 5 3 17 9 11 hd3 unfiltered outputs hd2 filtered outputs hd2 unfiltered outputs hd3 filtered outputs output amplitude (dbm) ?1 distortion (dbc) ?50?55 ?60 ?70 ?65?75 ?80 ?85 ?90 ?95 ?100 19932 g17 5 3 17 9 11 hd3 unfiltered outputs hd3 filtered outputs hd2 unfiltered outputs hd2 filtered outputs frequency (mhz) 1 distortion (dbc) ?10?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 ?100?110 10 100 1000 19932 g15 unfiltered outputsv out = 2v p-p hd3 hd2 frequency (mhz) 1 distortion (dbc) ?10?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 ?100?110 10 100 1000 19932 g14 unfiltered outputsv out = 2v p-p hd3 hd2 frequency (mhz) 1 distortion (dbc) ?10?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 ?100?110 10 100 1000 19932 g13 unfiltered outputsv out = 2v p-p hd3 hd2 frequency (mhz) 1 distortion (dbc) ?10?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 ?100?110 10 100 1000 19932 g12 filtered outputsv out = 2v p-p hd3 hd2 frequency (mhz) 1 distortion (dbc) ?10?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 ?100?110 10 100 1000 19932 g10 filtered outputsv out = 2v p-p hd3 hd2 frequency (mhz) 1 distortion (dbc) ?10?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 ?100?110 10 100 1000 19932 g11 filtered outputsv out = 2v p-p hd3 hd2 distortion (filtered) vs frequency differential input, no r load distortion (filtered) vs frequency differential input, r load = 400 distortion (filtered) vs frequency differential input, r load = 100 distortion (un? ltered) vs frequency, differential input, no r load distortion (un? ltered) vs frequency, differential input, r load = 400 distortion (un? ltered) vs frequency, differential input, r load = 100 distortion vs output amplitude 70mhz differential input, no r load distortion vs output amplitude 70mhz differential input, r load = 400 distortion vs output amplitude 70mhz differential input, r load = 100 typical perfor a ce characteristics uw downloaded from: http:///
lt1993-2 8 19932fa output amplitude (dbm) ?1 distortion (dbc) ?50?55 ?60 ?70 ?65?75 ?80 ?85 ?90 ?95 ?100 19932 g27 5 3 17 9 11 hd3 unfiltered outputs hd2 unfiltered outputs hd2 filtered outputs hd3 filtered outputs output amplitude (dbm) ?1 distortion (dbc) ?50?55 ?60 ?70 ?65?75 ?80 ?85 ?90 ?95 ?100 19932 g26 5 3 17 9 11 hd3 unfiltered outputs hd2 unfiltered outputs hd3 filtered outputs hd2 filtered outputs output amplitude (dbm) ?1 distortion (dbc) ?50?55 ?60 ?70 ?65?75 ?80 ?85 ?90 ?95 ?100 19932 g25 5 3 17 9 11 hd3 unfiltered outputs hd2 unfiltered outputs hd3 filtered outputs hd2 filtered outputs frequency (mhz) 1 distortion (dbc) ?10?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 ?100?110 10 100 1000 19932 g22 hd3 hd2 unfiltered outputsv out = 2v p-p frequency (mhz) 1 distortion (dbc) ?10?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 ?100?110 10 100 1000 19932 g24 hd3 hd2 unfiltered outputsv out = 2v p-p frequency (mhz) 1 distortion (dbc) ?10?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 ?100?110 10 100 1000 19932 g23 hd3 hd2 unfiltered outputsv out = 2v p-p frequency (mhz) 1 distortion (dbc) ?10?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 ?100?110 10 100 1000 19932 g20 filtered outputsv out = 2v p-p hd3 hd2 frequency (mhz) 1 distortion (dbc) ?10?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 ?100?110 10 100 1000 19932 g19 filtered outputsv out = 2v p-p hd3 hd2 frequency (mhz) 1 distortion (dbc) ?10?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 ?100?110 10 100 1000 19932 g21 filtered outputsv out = 2v p-p hd3 hd2 distortion (filtered) vs frequency single-ended input, no r load distortion (filtered) vs frequency single-ended input, r load = 400 distortion (filtered) vs frequency single-ended input, r load = 100 distortion (un? ltered) vs frequency, single-ended input, no r load distortion (un? ltered) vs frequency, single-ended input, r load = 400 distortion (un? ltered) vs frequency, single-ended input, r load = 100 distortion vs output amplitude 70mhz single-ended input, no r load distortion vs output amplitude 70mhz single-ended input, r load = 400 distortion vs output amplitude 70mhz single-ended input, r load = 100 typical perfor a ce characteristics uw downloaded from: http:///
lt1993-2 9 19932fa frequency (mhz) 1 psrr, cmrr (db) 100 9080 70 60 50 40 30 20 10 0 10 100 1000 19932 g36 cmrr psrr unfiltered outputs frequency (mhz) 10 input reflection coefficient (s11) 0 ?5 ?50 ?45 ?40 ?35 ?30 ?25 ?20 ?15 ?10 100 1000 19932 g34 measured using dc800a demo board frequency (mhz) isolation (db) ?40?50 ?60 ?70 ?80 ?90 ?100?110 1 100 1000 10000 19932 g31 10 unfiltered outputs frequency (mhz) 1 input impedance (magnitude ? , phase ) 300250 200 150 100 50 0 ?50 ?100 10 100 1000 19932 g32 impedance magnitude impedance phase frequency (mhz) 1 0.1 output impedance ( ? ) 1 10 100 10 100 1000 19932 g33 unfiltered outputs frequency (mhz) 10 output reflection coefficient (s22) 0 ?5 ?50 ?45 ?40 ?35 ?30 ?25 ?20 ?15 ?10 100 1000 19932 g35 measured using dc800a demo board frequency (mhz) 10 input referred noise voltage (nv/ hz) 12 64 8 10 20 100 1000 19932 g30 frequency (mhz) 10 noise figure (db) 2520 15 10 50 100 1000 19932 g29 v cc = 5v measured using dc800a demo board frequency (mhz) 1 output 1db compression (dbm) 3025 20 15 10 50 ?5 ?10 10 100 1000 19932 g28 r load = 400 ? r load = 100 ? unfiltered outputs output 1db compression vs frequency noise figure vs frequency input referred noise voltage vs frequency isolation vs frequency differential input impedance vs frequency differential output impedance vs frequency input re? ection coef? cient vs frequency output re? ection coef? cient vs frequency psrr, cmrr vs frequency typical perfor a ce characteristics uw downloaded from: http:///
lt1993-2 10 19932fa output common mode voltage (v) 1.2 distortion (dbc) ?64?66 ?68 ?72 ?70?74 ?76 19932 g40 1.8 1.6 1.4 2.0 2.2 2.6 2.4 filtered outputs, no r load v out = 70mhz 2v p-p hd3 hd2 time (ns) 0 voltage (v) 1 2 500 625 19932 g41 4 2 ?2 125 250 375 0 4 3 0 +out ?out enable r load = 100 ? per output time (ns) 0 output voltage (v) 2.0 2.5 3.0 225 200 250 19932 g39 1.5 1.0 0 50 100 150 175 25 75 125 0.5 4.0 3.5 +out ?out r load = 100 ? per output time (ns) 0 output voltage (v) 2.2 2.4 2.6 45 40 50 19932 g38 2.0 1.8 1.4 10 20 30 35 5 15 25 1.6 3.0 2.8 r load = 100 ? per output time (ns) 0 output voltage (v) 2.20 2.22 2.24 45 40 50 19932 g37 2.18 2.16 2.12 10 20 30 35 5 15 25 2.14 2.28 2.26 r load = 100 ? per output time (ns) 0 voltage (v) 1 2 500 625 19932 g42 4 2 ?2 125 250 375 0 4 3 0 +out ?out enable r load = 100 ? per output small-signal transient response large-signal transient response overdrive recovery time distortion vs output common mode voltage lt1993-2 driving ltc2249 14-bit adc turn-on time turn-off time typical perfor a ce characteristics uw downloaded from: http:///
lt1993-2 11 19932fa frequency (mhz) 0 amplitude (dbfs) 10 20 30 40 19932 g46 ?120 ?110 ?100 ?80 ?60 ?40 ?20?90 ?70 ?50 ?30 ?10 0 51 5 25 35 8192 point fftf in = 30mhz, ?1dbfs filtered outputs frequency (mhz) 0 amplitude (dbfs) 10 20 30 40 19932 g47 ?120 ?110 ?100 ?80 ?60 ?40 ?20?90 ?70 ?50 ?30 ?10 0 51 5 25 35 8192 point fftf in = 50mhz, ?1dbfs filtered outputs frequency (mhz) 0 amplitude (dbfs) 10 20 30 40 19932 g49 ?120 ?110 ?100 ?80 ?60 ?40 ?20?90 ?70 ?50 ?30 ?10 0 51 5 25 35 32768 point ffttone 1 at 69.5mhz, ?7dbfs tone 2 at 70.5mhz, ?7dbfs filtered outputs frequency (mhz) 0 amplitude (dbfs) 10 20 30 40 19932 g48 ?120 ?110 ?100 ?80 ?60 ?40 ?20?90 ?70 ?50 ?30 ?10 0 51 5 25 35 8192 point fftf in = 70mhz, ?1dbfs filtered outputs 0 ?20?40 ?80 ?60 ?100 ?10?30 ?50 ?90 ?70 ?110?120 frequency (mhz) 0 amplitude (dbfs) 19932 g50 15 10 52 0 2 5 45 30 35 40 32768 point ffttone center frequencies at 67.5mhz, 72.5mhz 0 ?20?40 ?80 ?60 ?100 ?10?30 ?50 ?90 ?70 ?110?120 frequency (mhz) 0 amplitude (dbfs) 19932 g51 15 10 52 0 2 5 45 30 35 40 32768 point ffttone center frequencies at 62.5mhz, 67.5mhz, 72.5mhz, 77.5mhz 30mhz 8192 point fft, lt1993-2 driving ltc2249 14-bit adc 50mhz 8192 point fft, lt1993-2 driving ltc2249 14-bit adc 70mhz 8192 point fft, lt1993-2 driving ltc2249 14-bit adc 70mhz 2-tone 32768 point fft, lt1993-2 driving ltc2249 14-bit adc 2-tone wcdma waveform, lt1993-2 driving ltc2255 14-bit adc at 92.16msps 4-tone wcdma waveform, lt1993-2 driving ltc2255 14-bit adc at 92.16msps typical perfor a ce characteristics uw downloaded from: http:///
lt1993-2 12 19932fa v ocm (pin 2): this pin sets the output common mode voltage. without additional biasing, both inputs bias to this voltage as well. this input is high impedance. v cca , v ccb , v ccc (pins 3, 10, 1): positive power supply (normally tied to 5v). all three pins must be tied to the same voltage. bypass each pin with 1000pf and 0.1f capacitors as close to the package as possible. split supplies are possible as long as the voltage between v cc and v ee is 5v. v eea , v eeb , v eec (pins 4, 9, 12): negative power supply (normally tied to ground). all three pins must be tied to the same voltage. split supplies are possible as long as the voltage between v cc and v ee is 5v. if these pins are not tied to ground, bypass each pin with 1000pf and 0.1f capacitors as close to the package as possible. +out, Cout (pins 5, 8): outputs (un? ltered). these pins are high bandwidth, low-impedance outputs. the dc output voltage at these pins is set to the voltage applied at v ocm . +outfiltered, Coutfiltered (pins 6, 7): filtered outputs. these pins add a series 25 resistor from the un? ltered outputs and three 12pf capacitors. each output has 12pf to v ee , plus an additional 12pf between each pin (see the block diagram). this ? lter has a C3db bandwidth of 175mhz. enable (pin 11): this pin is a ttl logic input referenced to the v eec pin. if low, the lt1993-2 is enabled and draws typically 100ma of supply current. if high, the lt1993-2 is disabled and draws typically 250a. +ina, +inb (pins 15, 16): positive inputs. these pins are normally tied together. these inputs may be dc- or ac- coupled. if the inputs are ac-coupled, they will self-bias to the voltage applied to the v ocm pin. Cina, Cinb (pins 14, 13): negative inputs. these pins are normally tied together. these inputs may be dc- or ac- coupled. if the inputs are ac-coupled, they will self-bias to the voltage applied to the v ocm pin. exposed pad (pin 17): tie the pad to v eec (pin 12). if split supplies are used, do not tie the pad to ground. pi fu ctio s uuu downloaded from: http:///
lt1993-2 13 19932fa + ? 14 ? ina 5 +out 19932 bd 3 v cca 10 v ccb 1 v ccc 11 enable 13 ? inb 12pf v cca a v eea v eea 200 ? 200 ? 200 ? 200 ? 25 ? 200 ? 6 +outfiltered ? + 16 +ina 8 ?out 15 +inb v ccb b v eeb v eeb 200 ? 200 ? 25 ? 200 ? 12pf 12pf 7 ?outfiltered 12 v eec 9 v eeb 4 v eea + ? v eec c v ccc 2 v ocm bias block diagra w downloaded from: http:///
lt1993-2 14 19932fa applicatio s i for atio wu u u circuit description the lt1993-2 is a low-noise, low-distortion differential ampli? er/adc driver with: ? dc to 800mhz C3db bandwidth ? fixed gain of 2v/v (6db) independent of r load ? 200 differential input impedance ? low output impedance ? built-in, user adjustable output ? ltering ? requires minimal support circuitry referring to the block diagram, the lt1993-2 uses a closed- loop topology which incorporates 3 internal ampli? ers. two of the ampli? ers (a and b) are identical and drive the differential outputs. the third ampli? er (c) is used to set the output common mode voltage. gain and input impedance are set by the 200 resistors in the internal feedback network. output impedance is low, determined by the inherent output impedance of ampli? ers a and b, and further reduced by internal feedback. the lt1993-2 also includes built-in single-pole output ? ltering. the user has the choice of using the un? ltered outputs, the ? ltered outputs (175mhz C3db lowpass), or modifying the ? ltered outputs to alter frequency response by adding additional components. many lowpass and bandpass ? lters are easily implemented with just one or two additional components. the lt1993-2 has been designed to minimize the need for external support components such as transformers or ac-coupling capacitors. as an adc driver, the lt1993-2 requires no external components except for power-supply bypass capacitors. this allows dc-coupled operation for applications that have frequency ranges including dc. at the outputs, the common mode voltage is set via the v ocm pin, allowing the lt1993-2 to drive adcs directly. no output ac-coupling capacitors or transformers are needed. at the inputs, signals can be differential or single-ended with virtually no difference in performance. furthermore, dc levels at the inputs can be set independently of the output common mode voltage. these input characteristics often eliminate the need for an input transformer and/or ac-coupling capacitors. input impedance and matching networksbecause of the internal feedback network, calculation of the lt1993-2s input impedance is not straightforward from examination of the block diagram. furthermore, the input impedance when driven differentially is different than when driven single-ended. when driven differentially, the lt1993-2s input impedance is 200 (differential); when driven single-ended, the input impedance is 133 . for single-ended 50 applications, an 80.6 shunt matching resistor to ground will result in the proper input termination (figure 1). for differential inputs there are several termination options. if the input source is 50 differential, then input matching can be accomplished by either a 67 shunt resistor across the inputs (figure 3), or a 33 shunt resistor on each of the inputs to ground (figure 2). if additional ac gain is desired, a 1:4 impedance ratio transformer (like the mini-circuits tcm4-19) can also be used to better match impedances and to provide an ad- ditional 6db of gain (figure 4). with a 1:4 impedance ratio transformer, ideal matching impedance at the transformer output is 200 , so no termination resistors are required to match the lt1993-2s 200 input impedance. 19932 f01 if in 0.1 f lt1993-2 ?ina ?inb ?out+out 85 +inb+ina 14 1315 80.6 ? z in = 50 ? single-ended 16 figure 1. input termination for single-ended 50 input impedance figure 2. input termination for differential 50 input impedance 19932 f02 if in ? if in + lt1993-2 ?ina ?inb ?out+out 85 +inb+ina 14 1315 33 ? z in = 50 ? differential 16 33 ? downloaded from: http:///
lt1993-2 15 19932fa applicatio s i for atio wu u u single-ended to differential operation the lt1993-2s performance with single-ended inputs is comparable to its performance with differential inputs. this excellent single-ended performance is largely due to the internal topology of the lt1993-2. referring to the block diagram, if the +ina and +inb pins are driven with a single-ended signal (while Cina and Cinb are tied to ac ground), then the +out and Cout pins are driven differentially without any voltage swing needed from ampli? er c. single-ended to differential conversion using more conventional topologies suffers from performance limitations due to the common mode ampli? er. driving adcs the lt1993-2 has been speci? cally designed to interface directly with high speed analog to digital converters (adcs). in general, these adcs have differential inputs, with an input impedance of 1k or higher. in addition, there is generally some form of lowpass or bandpass ? ltering just prior to the adc to limit input noise at the adc, thereby improving system signal to noise ratio. both the un? ltered and ? ltered outputs of the lt1993-2 can easily drive the high impedance inputs of these differential adcs. if the ? ltered outputs are used, then cutoff frequency and the type of ? lter can be tailored for the speci? c application if needed. wideband applications (using the +out and Cout pins) in applications where the full bandwidth of the lt1993-2 is desired, the un? ltered output pins (+out and Cout) should be used. they have a low output impedance; therefore, gain is unaffected by output load. capacitance in excess of 5pf placed directly on the un? ltered outputs results in additional peaking and reduced performance. when driving an adc directly, a small series resistance is recommended between the lt1993-2s outputs and the adc inputs (figure 5). this resistance helps eliminate any resonances associated with bond wire inductances of either the adc inputs or the lt1993-2s outputs. a value between 10 and 25 gives excellent results. figure 3. alternate input termination for differential 50 input impedance figure 4. input termination for differential 50 input impedance with 6db additional gain 19932 f02 if in ? if in + lt1993-2 ?ina ?inb ?out+out 85 +inb+ina 14 1315 z in = 50 ? differential 16 67 ? 19932 f04 0.1 f lt1993-2 ?ina ?inb ?out+out 85 +inb+ina 14 1315 z in = 50 ? differential 1:4 transformer (mini-circuits tcm4-19) 16 19932 f05 lt1993-2 ?out+out 85 10 ? to 25 ? 10 ? to 25 ? adc figure 5. adding small series r at lt1993-2 output filtered applications (using the +outfiltered and Coutfiltered pins) filtering at the output of the lt1993-2 is often desired to provide either anti-aliasing or improved signal to noise ratio. to simplify this ? ltering, the lt1993-2 includes an additional pair of differential outputs (+outfiltered and Coutfiltered) which incorporate an internal low- pass ? lter network with a C3db bandwidth of 175mhz (figure 6). these pins each have an output impedance of 25 . internal capacitances are 12pf to v ee on each ? ltered output, plus an additional 12pf capacitor con- nected differentially between the two ? ltered outputs. this resistor/capacitor combination creates ? ltered outputs downloaded from: http:///
lt1993-2 16 19932fa applicatio s i for atio wu u u that look like a series 25 resistor with a 36pf capacitor shunting each ? ltered output to ac ground, giving a C3db bandwidth of 175mhz. it will appear at each ? ltered output as a single-ended capacitance of twice the value. to halve the ? lter band- width, for example, two 36pf capacitors could be added (one from each ? ltered output to ground). alternatively one 18pf capacitor could be added between the ? ltered outputs, again halving the ? lter bandwidth. combinations of capacitors could be used as well; a three capacitor solution of 12pf from each ? ltered output to ground plus a 12pf capacitor between the ? ltered outputs would also halve the ? lter bandwidth (figure 8). the ? lter cutoff frequency is easily modi? ed with just a few external components. to increase the cutoff frequency, simply add 2 equal value resistors, one between +out and +outfiltered and the other between Cout and Coutfil- tered (figure 7). these resistors are in parallel with the internal 25 resistor, lowering the overall resistance and increasing ? lter bandwidth. to double the ? lter bandwidth, for example, add two external 25 resistors to lower the series resistance to 12.5 . the 36pf of capacitance remains unchanged, so ? lter bandwidth doubles. figure 6. lt1993-2 internal filter topology C3db bw 175mhz figure 7. lt1993-2 internal filter topology modi? ed for 2x filter bandwidth (2 external resistors) bandpass ? ltering is also easily implemented with just a few external components. an additional 120pf and 39nh, each added differentially between +outfiltered and Coutfiltered creates a bandpass ? lter with a 71mhz center frequency, C3db points of 55mhz and 87mhz, and 1.6db of insertion loss (figure 9). figure 8. lt1993-2 internal filter topology modi? ed for 1/2x filter bandwidth (3 external capacitors) 19932 f06 25 ? v ee v ee 12pf lt1993-2 ?out+out 25 ? 12pf 12pf ?outfiltered+outfiltered 8 7 6 5 filtered output(175mhz) v ee v ee 19932 f07 25 ? 25 ? 12pf lt1993-2 ?out+out 25 ? 25 ? 12pf 12pf ?outfiltered filtered output(350mhz) +outfiltered 8 7 6 5 to decrease ? lter bandwidth, add two external capacitors, one from +outfiltered to ground, and the other from Coutfiltered to ground. a single differential capacitor connected between +outfiltered and Coutfiltered can also be used, but since it is being driven differentially v ee v ee 19932 f08 25 ? 12pf lt1993-2 ?out+out 25 ? 12pf 12pf 12pf 12pf 12pf ?outfiltered+outfiltered 8 7 6 5 filtered output(87.5mhz) figure 9. lt1993-2 output filter topology modi? ed for bandpass filtering (1 external inductor, 1 external capacitor) v ee v ee 19932 f09 25 ? 12pf lt1993-2 ?out+out 25 ? 12pf 12pf 120pf 39nh ?outfiltered+outfiltered 8 7 6 5 filtered output(71mhz bandpass, ?3db @ 55mhz/87mhz) downloaded from: http:///
lt1993-2 17 19932fa applicatio s i for atio wu u u output common mode adjustment the lt1993-2s output common mode voltage is set by the v ocm pin. it is a high-impedance input, capable of setting the output common mode voltage anywhere in a range from 1.1v to 3.6v. bandwidth of the v ocm pin is typically 300mhz, so for applications where the v ocm pin is tied to a dc bias voltage, a 0.1f capacitor at this pin is recom- mended. for best distortion performance, the voltage at the v ocm pin should be between 1.8v and 2.6v. when interfacing with most adcs, there is generally a v ocm output pin that is at about half of the supply voltage of the adc. for 5v adcs such as the ltc17xx family, this v ocm output pin should be connected directly (with the addition of a 0.1f capacitor) to the input v ocm pin of the lt1993-2. for 3v adcs such as the ltc22xx families, the lt1993-2 will function properly using the 1.65v from the adcs v cm reference pin, but improved spurious free dynamic range (sfdr) and distortion performance can be achieved by level-shifting the ltc22xxs v cm reference voltage up to at least 1.8v. this can be accomplished as shown in figure 10 by using a resistor divider between the ltc22xxs v cm output pin and v cc and then bypass- ing the lt1993-2s v ocm pin with a 0.1f capacitor. for a common mode voltage above 1.9v, ac coupling capacitors are recommended between the lt1993-2 and ltc22xx adcs because of the input voltage range constraints of the adc. large output voltage swings the lt1993-2 has been designed to provide the 3.2v p-p output swing needed by the ltc1748 family of 14-bit low-noise adcs. this additional output swing improves system snr by up to 4db. typical performance curves and ac speci? cations have been included for these ap- plications. input bias voltage and bias current the input pins of the lt1993-2 are internally biased to the voltage applied to the v ocm pin. no external biasing resistors are needed, even for ac-coupled operation. the input bias current is determined by the voltage difference between the input common mode voltage and the v ocm pin (which sets the output common mode voltage). at both the positive and negative inputs, any voltage difference is imposed across 200 , generating an input bias current. for example, if the inputs are tied to 2.5v with the v ocm pin at 2.2v, then a total input bias current of 1.5ma will ? ow into the lt1993-2s +ina and +inb pins. furthermore, an additional input bias current totaling 1.5ma will ? ow into the Cina and Cinb inputs. application (demo) boards the dc800a demo board has been created for stand-alone evaluation of the lt1993-2 with either single-ended or differential input and output signals. as shown, it accepts a single-ended input and produces a single-ended output so that the lt1993-2 can be evaluated using standard laboratory test equipment. for more information on this demo board, please refer to the demo board section of this data sheet. there are also additional demo boards available that combine the lt1993-2 with a variety of different linear technology adcs. please contact the factory for more information on these demo boards. 19932 f10 if in lt1993-2 ?ina ?inb v ocm 2 31 67 12 +inb+ina 14 1315 80.6 ? 16 10 ? 10 ? ltc22xx 0.1 f 0.1 f +outfiltered?outfiltered ain + ain ? 4.02k 11k 1.9v 1.5v 3v v cm figure 10. level shifting 3v adc v cm voltage for improved sfdr downloaded from: http:///
lt1993-2 18 19932fa typical applicatio u downloaded from: http:///
lt1993-2 19 19932fa 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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 3.00 0.10 (4 sides) recommended solder pad pitch and dimensions 1.45 0.05 (4 sides) note:1. drawing conforms to jedec package outline mo-220 variation (weed-2) 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 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 1top mark (note 6) 0.40 0.10 bottom view?exposed pad 1.45 0.10 (4-sides) 0.75 0.05 r = 0.115 typ 0.25 0.05 1 pin 1 notch r = 0.20 typor 0.25 45 chamfer 15 16 2 0.50 bsc 0.200 ref 2.10 0.05 3.50 0.05 0.70 0.05 0.00 ? 0.05 (ud16) qfn 0904 0.25 0.05 0.50 bsc package outline ud package 16-lead plastic qfn (3mm 3mm) (reference ltc dwg # 05-08-1691) package descriptio u downloaded from: http:///
lt1993-2 20 19932fa ? linear technology corporation 2005 lt/lt 1005 rev a ? printed in usa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com part number description comments lt1993-4 900mhz differential ampli? er/adc driver a v = 4v/v, nf = 14.5db, oip3 = 40dbm at 70mhz lt1993-10 700mhz differential ampli? er/adc driver a v = 10v/v, nf = 12.7db, oip3 = 40dbm at 70mhz lt5514 ultralow distortion if ampli? er/adc driver digitally controlled gain output ip3 47dbm at 100mhz lt6600-2.5 very low noise differential ampli? er and 2.5mhz lowpass filter 86db s/n with 3v supply, so-8 package lt6600-5 very low noise differential ampli? er and 5mhz lowpass filter 82db s/n with 3v supply, so-8 package lt6600-10 very low noise differential ampli? er and 10mhz lowpass filter 82db s/n with 3v supply, so-8 package lt6600-20 very low noise differential ampli? er and 20mhz lowpass filter 76db s/n with 3v supply, so-8 package typical applicatio u related parts c20, 0.1 f v cc c144.7 f c151 f j6 test in j7test out j3 v ocm 31 2 4 1 5 v cc v cc c10 0.01 f c9 1000pf 19932 ta02 1314 15 16 11 10 9 12 v cc v cc gnd sw1 23 4 1 87 6 5 r8 [1] r10 24.9 ? r6 0 ? r18 0 ? r5 0 ? r7 [1] r9 24.9 ? r12 75 ? r16 0 ? r15 [1] +6db r11 75 ? +6db c180.01 f notes: unless otherwise specified,[1] do not stuff. c4 0.1 f c3 0.1 f c2 0.1 f c1 0.1 f t1 1:4 z-ratio mini- circuits tcm 4-19 mini- circuits tcm 4-19 mini- circuits tcm 4-19 t2 1:4 z-ratio c171000pf c130.01 f c121000pf r22 [1] r21 [1] c70.01 f ?ina ?inb+inb +ina v eec v ccb v eeb v ocm v cca v ccc v eea ?outfiltered ?out +outfiltered +out enable tp1 enable r14 0 ? j4?out j5+out r13 [1] 54 2 2 13 3 r4 [1] r3 [1] r2 0 ? j1 ?in j2 +in r1 1 ? 0db r20 11k r19 14k r17 0 ? v cc v cc tp2 v cc c5 0.1 f c6 0.1 f t4 4:1 5 4 31 2 tp3 gnd lt1993-2 1 21 21 21 21 21 c21 0.1 f 21 1 t3 1:4 54 2 3 c19, 0.1 f 21 21 21 21 21 21 21 21 21 c8[1] l1[1] 21 c11[1] 12 21 1 1 c220.1 f 21 c16[1] 12 21 21 +10.8db 0db mini- circuits tcm 4-19 demo circuit dc800a schematic (ac test circuit) downloaded from: http:///

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