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LTC1992 family 1 1992f differential driver/receiver differential amplification single-ended to differential conversion level shifting trimmed phase response for multichannel systems adjustable gain and fixed gain blocks of 1, 2, 5 and 10 0.3% (max) gain error from ?0 c to 85 c 3.5ppm/ c gain temperature coefficient 5ppm gain long term stability fully differential input and output c load stable up to 10,000pf adjustable output common mode voltage rail-to-rail output swing low supply current: 1ma (max) high output current: 10ma (min) specified on a single 2.7v to 5v supply dc offset voltage <2.5mv (max) available in 8-lead msop package low power, fully differential input/output amplifier/driver family single-supply, single-ended to differential conversion the ltc ? 1992 product family consists of five fully differ- ential, low power amplifiers. the LTC1992 is an uncon- strained fully differential amplifier. the LTC1992-1, LTC1992-2, LTC1992-5 and LTC1992-10 are fixed gain blocks (with gains of 1, 2, 5 and 10 respectively) featuring precision on-chip resistors for accurate and ultrastable gain. all of the LTC1992 parts have a separate internal common mode feedback path for outstanding output phase balancing and reduced second order harmonics. the v ocm pin sets the output common mode level inde- pendent of the input common mode level. this feature makes level shifting of signals easy. the amplifiers differential inputs operate with signals ranging from rail-to-rail with a common mode level from the negative supply up to 1.3v from the positive supply. the differential input dc offset is typically 250 v. the rail- to-rail outputs sink and source 10ma. the LTC1992 is stable for all capacitive loads up to 10,000pf. the LTC1992 can be used in single supply applications with supply voltages as low as 2.7v. it can also be used with dual supplies up to 5v. the LTC1992 is available in an 8-pin msop package. features descriptio u applicatio s u typical applicatio u C C + + 5v 5v LTC1992 3 6 v ocm v mid 0v 2.5v 0v v in 0.01 f 1992 ta01a 4 5 2 7 8 1 10k 10k 10k 10k 5v 0v 5v C5v 2.5v input signal from a 5v system output signal from a single-supply system v in (5v/div) +out Cout (2v/div) 5v 0v C5v 5v 0v 1992 ta01b , ltc and lt are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners.
LTC1992 family 2 1992f total supply voltage (+v s to Cv s ) .......................... 12v maximum voltage on any pin .......... (Cv s C 0.3v) v pin (+v s + 0.3v) output short-circuit duration (note 3) ............ indefinite operating temperature range (note 5) LTC1992cms8/LTC1992-xcms8/ LTC1992ims8/LTC1992-xims8 ..........C40 c to 85 c LTC1992hms8/LTC1992-xhms8 .....C40 c to 125 c LTC1992cms8 LTC1992ims8 LTC1992hms8 (note 1) ltyu ltzc ltagr absolute axi u rati gs w ww u specified temperature range (note 6) LTC1992cms8/LTC1992-xcms8/ LTC1992ims8/LTC1992-xims8 ..........C40 c to 85 c LTC1992hms8/LTC1992-xhms8 .....C40 c to 125 c storage temperature range ................ C 65 c to 150 c lead temperature (soldering, 10 sec).................. 300 c package/order i for atio uu w order part number LTC1992-1cms8 LTC1992-1ims8 LTC1992-1hms8 LTC1992-2cms8 LTC1992-2ims8 LTC1992-2hms8 LTC1992-5cms8 LTC1992-5ims8 LTC1992-5hms8 LTC1992-10cms8 LTC1992-10ims8 LTC1992-10hms8 ms8 part marking ltacj ltacm ltafz ltyv ltzd ltaga ltack ltacn ltajh ltacl ltacp ltajj 1 2 3 4 Cin v ocm +v s +out 8 7 6 5 +in v mid Cv s Cout top view ms8 package 8-lead plastic msop + + C C t jmax = 150 c, ja = 250 c/w order part number ms8 part marking consult ltc marketing for parts specified with wider operating temperature ranges. t jmax = 150 c, ja = 250 c/w 1 2 3 4 Cin v ocm +v s +out 8 7 6 5 +in v mid Cv s Cout top view ms8 package 8-lead plastic msop + + C C
LTC1992 family 3 1992f the denotes specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. +v s = 5v, v s = 0v, v incm = v outcm = v ocm = 2.5v, unless otherwise noted. v ocm is the voltage on the v ocm pin. v outcm is defined as (+v out + ? out )/2. v incm is defined as (+v in + ? in )/2. v indiff is defined as (+v in ?? in ). v outdiff is defined as (+v out ?? out ). specifications applicable to all parts in the LTC1992 family. electrical characteristics all c and i grade all h grade symbol parameter conditions min typ max min typ max units v s supply voltage range 2.7 11 2.7 11 v i s supply current v s = 2.7v to 5v 0.65 1.0 0.65 1.0 ma 0.75 1.2 0.8 1.5 ma v s = 5v 0.7 1.2 0.7 1.2 ma 0.8 1.5 0.9 1.8 ma v osdiff differential offset voltage v s = 2.7v 0.25 2.5 0.25 4mv (input referred) (note 7) v s = 5v 0.25 2.5 0.25 4mv v s = 5v 0.25 2.5 0.25 4mv ? v osdiff / ? t differential offset voltage drift v s = 2.7v 10 10 v/ c (input referred) (note 7) v s = 5v 10 10 v/ c v s = 5v 10 10 v/ c psrr power supply rejection ratio v s = 2.7v to 5v 75 80 72 80 db (input referred) (note 7) g cm common mode gain(v outcm /v ocm ) 11 common mode gain error 0.1 0.3 0.1 0.35 % output balance ( ? v outcm /( ? v outdiff )v outdiff = C2v to +2v C85 C60 C85 C60 db v oscm common mode offset voltage v s = 2.7v 0.5 12 0.5 15 mv (v outcm C v ocm )v s = 5v 1 15 1 17 mv v s = 5v 2 18 2 20 mv ? v oscm / ? t common mode offset voltage drift v s = 2.7v 10 10 v/ c v s = 5v 10 10 v/ c v s = 5v 10 10 v/ c v outcmr output signal common mode range (Cv s )+0.5v (+v s )C1.3v (Cv s )+0.5v (+v s )C1.3v v (voltage range for the v ocm pin) r invocm input resistance, v ocm pin 500 500 m ? i bvocm input bias current, v ocm pin v s = 2.7v to 5v 2 2pa v mid voltage at the v mid pin 2.44 2.50 2.56 2.43 2.50 2.57 v v out output voltage, high v s = 2.7v, load = 10k 2.60 2.69 2.60 2.69 v (note 2) v s = 2.7v, load = 5ma 2.50 2.61 2.50 2.61 v v s = 2.7v,load = 10ma 2.29 2.52 2.29 2.52 v output voltage, low v s = 2.7v, load = 10k 0.02 0.10 0.02 0.10 v (note 2) v s = 2.7v, load = 5ma 0.10 0.25 0.10 0.25 v v s = 2.7v, load = 10ma 0.20 0.35 0.20 0.41 v output voltage, high v s = 5v, load = 10k 4.90 4.99 4.90 4.99 v (note 2) v s = 5v, load = 5ma 4.85 4.90 4.80 4.90 v v s = 5v, load = 10ma 4.75 4.81 4.70 4.81 v output voltage, low v s = 5v, load = 10k 0.02 0.10 0.02 0.10 v (note 2) v s = 5v, load = 5ma 0.10 0.25 0.10 0.30 v v s = 5v, load = 10ma 0.20 0.35 0.20 0.42 v output voltage, high v s = 5v, load = 10k 4.90 4.99 4.85 4.99 v (note 2) v s = 5v, load = 5ma 4.85 4.89 4.80 4.89 v v s = 5v, load = 10ma 4.65 4.80 4.60 4.80 v output voltage, low v s = 5v, load = 10k C 4.99 C4.90 C4.98 C4.85 v (note 2) v s = 5v, load = 5ma C 4.90 C4.75 C4.90 C4.75 v v s = 5v, load = 10ma C 4.80 C4.65 C4.80 C4.55 v
LTC1992 family 4 1992f the denotes specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. +v s = 5v, v s = 0v, v incm = v outcm = v ocm = 2.5v, unless otherwise noted. v ocm is the voltage on the v ocm pin. v outcm is defined as (+v out + ? out )/2. v incm is defined as (+v in + ? in )/2. v indiff is defined as (+v in ?? in ). v outdiff is defined as (+v out ?? out ). specifications applicable to all parts in the LTC1992 family. electrical characteristics all c and i grade all h grade symbol parameter conditions min typ max min typ max units i sc output short-circuit current v s = 2.7v, v out = 1.35v 20 30 20 30 ma sourcing (notes 2,3) v s = 5v, v out = 2.5v 20 30 20 30 ma v s = 5v, v out = 0v 20 30 20 30 ma output short-circuit current sinking v s = 2.7v, v out =1.35v 13 30 13 30 ma (notes 2,3) v s = 5v, v out = 2.5v 13 30 13 30 ma v s = 5v, v out = 0v 13 30 13 30 ma a vol large-signal voltage gain 80 80 db the denotes specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. +v s = 5v, v s = 0v, v incm = v outcm = v ocm = 2.5v, unless otherwise noted. v ocm is the voltage on the v ocm pin. v outcm is defined as (+v out + ? out )/2. v incm is defined as (+v in + ? in )/2. v indiff is defined as (+v in ?? in ). v outdiff is defined as (+v out ?? out ). specifications applicable to the LTC1992 only. LTC1992cms8 LTC1992ism8 LTC1992hms8 symbol parameter conditions min typ max min typ max units i b input bias current v s = 2.7v to 5v 2 250 2 400 pa i os input offset current v s = 2.7v to 5v 0.1 100 0.1 150 pa r in input resistance 500 500 m ? c in input capacitance 33pf e n input referred noise voltage density f = 1khz 35 35 nv/ hz i n input noise current density f = 1khz 1 1 fa/ hz v incmr input signal common mode range v cmrr common mode rejection ratio v incm = C0.1v to 3.7v 69 90 69 90 db (input referred) sr slew rate (note 4) 0.5 1.5 0.5 1.5 v/ s gbw gain-bandwidth product t a = 25 c 3.0 3.2 3.5 3.0 3.2 3.5 mhz (f test = 100khz) LTC1992cms8 2.5 3.0 4.0 mhz LTC1992ims8/ 1.9 4.0 1.9 4.0 mhz LTC1992hms8 (Cv s )C 0.1v (+v s )C 1.3v (Cv s )C 0.1v (+v s )C 1.3v
LTC1992 family 5 1992f LTC1992-1cms8 LTC1992-1ims8 LTC1992-1hms8 symbol parameter conditions min typ max min typ max units g diff differential gain 1 1 v/v differential gain error 0.1 0.3 0.1 0.35 % differential gain nonlinearity 50 50 ppm differential gain temperature coefficient 3.5 3.5 ppm/ c e n input referred noise voltage density (note 7) f = 1khz 45 45 nv/ hz r in input resistance, single-ended +in, Cin pins 22.5 30 37.5 22 30 38 k ? v incmr input signal common mode range v s = 5v C 0.1v to 4.9v C 0.1v to 4.9v v cmrr common mode rejection ratio v incm = C0.1v to 3.7v 55 60 55 60 db (amplifier input referred) (note 7) sr slew rate (note 4) 0.5 1.5 0.5 1.5 v/ s gbw gain-bandwidth product f test = 180khz 3 3 mhz electrical characteristics the denotes specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. +v s = 5v, ? s = 0v, v incm = v outcm = v ocm = 2.5v, unless otherwise noted. v ocm is the voltage on the v ocm pin. v outcm is defined as (+v out + ? out )/2. v incm is defined as (+v in + ? in )/2. v indiff is defined as (+v in ?? in ). v outdiff is defined as (+v out ?? out ). typical values are at t a = 25 c. specifications apply to the LTC1992-1 only. LTC1992-2cms8 LTC1992-2ims8 LTC1992-2hms8 symbol parameter conditions min typ max min typ max units g diff differential gain 2 2 v/v differential gain error 0.1 0.3 0.1 0.35 % differential gain nonlinearity 50 50 ppm differential gain temperature coefficient 3.5 3.5 ppm/ c e n input referred noise voltage density (note 7) f = 1khz 45 45 nv/ hz r in input resistance, single-ended +in, Cin pins 22.5 30 37.5 22 30 38 k ? v incmr input signal common mode range v s = 5v C 0.1v to 4.9v C 0.1v to 4.9v v cmrr common mode rejection ratio v incm = C0.1v to 3.7v 55 60 55 60 db (amplifier input referred) (note 7) sr slew rate (note 4) 0.7 2 0.7 2 v/ s gbw gain-bandwidth product f test = 180khz 4 4 mhz the denotes specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. +v s = 5v, ? s = 0v, v incm = v outcm = v ocm = 2.5v, unless otherwise noted. v ocm is the voltage on the v ocm pin. v outcm is defined as (+v out + ? out )/2. v incm is defined as (+v in + ? in )/2. v indiff is defined as (+v in ?? in ). v outdiff is defined as (+v out ?? out ). typical values are at t a = 25 c. specifications apply to the LTC1992-2 only.
LTC1992 family 6 1992f LTC1992-5cms8 LTC1992-5ims8 LTC1992-5hms8 symbol parameter conditions min typ max min typ max units g diff differential gain 5 5 v/v differential gain error 0.1 0.3 0.1 0.35 % differential gain nonlinearity 50 50 ppm differential gain temperature coefficient 3.5 3.5 ppm/ c e n input referred noise voltage density (note 7) f = 1khz 45 45 nv/ hz r in input resistance, single-ended +in, Cin pins 22.5 30 37.5 22 30 38 k ? v incmr input signal common mode range v s = 5v C 0.1v to 3.9v C 0.1v to 3.9v v cmrr common mode rejection ratio v incm = C0.1v to 3.7v 55 60 55 60 db (amplifier input referred) (note 7) sr slew rate (note 4) 0.7 2 0.7 2 v/ s gbw gain-bandwidth product f test = 180khz 4 4 mhz electrical characteristics the denotes specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. +v s = 5v, ? s = 0v, v incm = v outcm = v ocm = 2.5v, unless otherwise noted. v ocm is the voltage on the v ocm pin. v outcm is defined as (+v out + ? out )/2. v incm is defined as (+v in + ? in )/2. v indiff is defined as (+v in ?? in ). v outdiff is defined as (+v out ?? out ). typical values are at t a = 25 c. specifications apply to the LTC1992-5 only. LTC1992-10cms8 LTC1992-10ims8 LTC1992-10hms8 symbol parameter conditions min typ max min typ max units g diff differential gain 10 10 v/v differential gain error 0.1 0.3 0.1 0.35 % differential gain nonlinearity 50 50 ppm differential gain temperature coefficient 3.5 3.5 ppm/ c e n input referred noise voltage density (note 7) f = 1khz 45 45 nv/ hz r in input resistance, single-ended +in, Cin pins 11.3 15 18.8 11 15 19 k ? v incmr input signal common mode range v s = 5v C 0.1v to 3.8v C 0.1v to 3.8v v cmrr common mode rejection ratio v incm = C0.1v to 3.7v 55 60 55 60 db (amplifier input referred) (note 7) sr slew rate (note 4) 0.7 2 0.7 2 v/ s gbw gain-bandwidth product f test = 180khz 4 4 mhz the denotes specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. +v s = 5v, ? s = 0v, v incm = v outcm = v ocm = 2.5v, unless otherwise noted. v ocm is the voltage on the v ocm pin. v outcm is defined as (+v out + ? out )/2. v incm is defined as (+v in + ? in )/2. v indiff is defined as (+v in ?? in ). v outdiff is defined as (+v out ?? out ). typical values are at t a = 25 c. specifications apply to the LTC1992-10 only. note 1: absolute maximum ratings are those values beyond which the life of a device may be impaired. note 2: output load is connected to the midpoint of the +v s and Cv s potentials. measurement is taken single-ended, one output loaded at a time. note 3: a heat sink may be required to keep the junction temperature below the absolute maximum when the output is shorted indefinitely. note 4: differential output slew rate. slew rate is measured single ended and doubled to get the listed numbers. note 5: the LTC1992c/LTC1992-xc/LTC1992i/LTC1992-xi are guaranteed functional over an operating temperature of C40 c to 85 c. the LTC1992h/LTC1992-xh are guaranteed functional over the extended operating temperature of C 40 c to 125 c. note 6: the LTC1992c/LTC1992-xc are guaranteed to meet the specified performance limits over the 0 c to 70 c temperature range and are designed, characterized and expected to meet the specified performance limits over the C40 c to 85 c temperature range but are not tested or qa sampled at these temperatures. the LTC1992i/LTC1992-xi are guaranteed to meet the specified performance limits over the C40 c to 85 c temperature range. the LTC1992h/LTC1992-xh are guaranteed to meet the specified performance limits over the C40 c to 125 c temperature range. note 7: differential offset voltage, differential offset voltage drift, cmrr, noise voltage density and psrr are referred to the internal amplifiers input to allow for direct comparison of gain blocks with discrete amplifiers.
LTC1992 family 7 1992f applicable to all parts in the LTC1992 family. differential input offset voltage vs temperature (note 7) total supply voltage (v) 0 supply current (ma) 0.6 0.8 1.0 8 1992 g01 0.4 0.2 0.5 0.7 0.9 0.3 0.1 0 2 1 4 3 67 9 5 10 125 c 85 c 25 c C40 c temperature ( c) C40 0.6 0.4 0.2 0 C0.2 C0.4 C0.6 C0.8 1992 g02 25 85 125 differential v os (mv) v incm = 0v v ocm = 0v v s = 1.35v v s = 2.5v v s = 5v temperature ( c) C40 C5 common mode v os (mv) C4 C2 C1 0 85 4 1992 g03 C3 25 125 1 2 3 v incm = 0v v ocm = 0v v s = 5v v s = 1.35v v s = 2.5v supply current vs supply voltage common mode offset voltage vs temperature common mode offset voltage vs v ocm voltage v ocm voltage (v) 0 C20 v ocm v os (mv) C15 C5 0 5 0.6 1.2 1.5 2.7 1992 g04 C10 0.3 0.9 1.8 2.1 2.4 125 c 85 c 25 c C40 c +v s = 2.7v Cv s = 0v v incm = 1.35v common mode offset voltage vs v ocm voltage v ocm voltage (v) 0 v ocm v os (mv) C5 0 5 4 1992 g05 C10 C15 C20 0.5 1 1.5 2 2.5 3 3.5 4.5 5 +v s = 5v Cv s = 0v v incm = 2.5v 125 c 85 c 25 c C40 c common mode offset voltage vs v ocm voltage v ocm voltage (v) C5 v ocm v os (mv) C5 0 5 3 1992 g06 C10 C15 C20 C4 C3 C2 C1 0 12 4 5 +v s = 5v Cv s = C5v v incm = 0v 125 c 85 c 25 c C40 c output voltage swing vs output load, v s = 2.7v load current (ma) C20 +swing (v) Cswing (v) 2.50 2.60 20 1992 g07 2.40 2.30 C10 0 10 C15 C5 5 15 2.70 2.45 2.55 2.35 2.65 0.4 0.6 0.2 0 0.8 0.3 0.5 0.1 0.7 C40 c C40 c 125 c 125 c 25 c 85 c 85 c 25 c output voltage swing vs output load, v s = 5v load current (ma) C20 20 4.50 +swing (v) Cswing (v) 4.55 4.65 4.70 4.75 5.00 4.85 C10 0 1992 g08 4.60 4.90 4.95 4.80 0 0.1 0.3 0.4 0.5 1.0 0.7 0.2 0.8 0.9 0.6 10 15 C15 C5 5 C40 c C40 c 125 c 125 c 85 c 85 c 25 c 25 c typical perfor a ce characteristics uw
LTC1992 family 8 1992f applicable to all parts in the LTC1992 family. v ocm input bias current vs v ocm voltage input common mode overdrive recovery (expanded view) 50 s/div 1v/div 1992 g13 both inputs (inputs tied together) outputs +v s = 2.5v Cv s = C2.5v v ocm = 0v LTC1992-10 shown for reference typical perfor a ce characteristics uw output voltage swing vs output load, v s = 5v load current (ma) C20 4.4 +swing (v) Cswing (v) 4.5 4.6 4.7 4.8 C10 0 10 20 C15 C5 5 15 1992 g09 4.9 5.0 C5.0 C4.8 C4.6 C4.4 C4.2 C4.0 C3.8 C40 c C40 c 125 c 125 c 85 c 25 c 85 c 25 c differential input offset voltage vs time (normalized to t = 0) input common mode overdrive recovery (detailed view) 1 s/div 1v/div 1992 g14 both inputs (inputs tied together) outputs +v s = 2.5v Cv s = C2.5v v ocm = 0v LTC1992-10 shown for reference output overdrive recovery (expanded view) 50 s/div 1v/div 1992 g15 +v s = 2.5v, Cv s = C2.5v, v ocm = 0v outputs inputs LTC1992-2 shown for reference output overdrive recovery (detailed view) 5 s/div 1v/div 1992 g16 inputs outputs +v s = 2.5v Cv s = C2.5v v ocm = 0v LTC1992-2 shown for reference differential gain vs time (normalized to t = 0) time (hours) 100 80 60 40 20 0 C20 C40 C60 C80 C100 delta v os ( v) 1992 g11 0 400 800 1200 1600 2000 temp = 35 c time (hours) 10 8 6 4 2 0 C2 C4 C6 C8 C10 delta gain (ppm) 1992 g12 0 400 800 1200 1600 2000 temp = 35 c v ocm voltage (v) 0 0.5 1 v ocm input bias current (a) 1.5 2 2.5 3 3.5 4 4.5 5 1992 g10 100e-15 10e-9 1e-9 100e-12 10e-12 1e-12 +v s = 5v Cv s = 0v v incm = 2.5v 125 c 85 c 25 c C40 c
LTC1992 family 9 1992f applicable to the LTC1992 only. differential input differential gain vs frequency, v s = 2.5v single-ended input differential gain vs frequency, v s = 2.5v frequency (khz) 10 C24 gain (db) C18 C12 C6 0 100 1000 10000 1992 g17 C30 C36 C42 C66 C60 C54 C48 6 12 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf r in = r fb = 10k frequency (khz) 10 C24 gain (db) C18 C12 C6 0 100 1000 10000 1992 g18 C30 C36 C42 C66 C60 C54 C48 6 12 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf r in = r fb = 10k differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage common mode rejection ratio vs frequency (note 7) power supply rejection ratio vs frequency (note 7) output balance vs frequency frequency (hz) 40 cmrr (db) 80 120 20 60 100 100 10k 100k 1m 1992 g23 0 1k ? v ampcm ? v ampdiff frequency (hz) 10 40 psrr (db) 50 60 70 80 100 1k 10k 100k 1m 1992 g24 30 20 10 0 90 100 Cv s +v s ? v s ? v ampdiff frequency (hz) 110 C40 output balance (db) C60 C80 100 1k 10k 100k 1m 1992 g25 C20 0 C100 ? v outcm ? v outdiff typical perfor a ce characteristics uw common mode voltage (v) 0 4.0 1922 g21 1.0 0.5 1.5 2.5 3.5 4.5 2.0 3.0 5.0 125 c C40 c 85 c 25 c differential v os (mv) 2.0 1.5 1.0 0.5 0 C 0.5 C1.0 C1.5 C2.0 +v s = 5v Cv s = 0v v ocm = 2.5v common mode voltage (v) 0 differential v os (mv) 1922 g20 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 2.0 1.5 1.0 0.5 0 C0.5 C1.0 C1.5 C2.0 125 c C40 c 25 c 85 c +v s = 2.7v Cv s = 0v v ocm = 1.35v common mode voltage (v) C5 3 1922 g22 C3 C4 C2 0 2 4 C1 1 5 125 c C40 c 85 c differential v os (mv) 2.0 1.5 1.0 0.5 0 C0.5 C1.0 C1.5 C2.0 25 c +v s = 5v Cv s = C5v v ocm = 0v differential phase response vs frequency frequency (khz) 10 phase (deg) 0 C20 C40 C60 C80 C100 C120 C140 C160 C180 100 1000 1992 g37 c load = 10pf 50pf 100pf 500pf 1000pf 5000pf 10000pf r in = r fb = 10k
LTC1992 family 10 1992f applicable to the LTC1992 only. differential input large-signal step response single-ended input large-signal step response differential input small-signal step response 2 s/div v outdiff (1v/div) 1992 g26 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 1.5v Cv in = 1.5v c load = 0pf gain = 1 0v 20 s/div 1992 g27 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 1.5v Cv in = 1.5v gain = 1 c load = 10000pf c load = 1000pf v outdiff (1v/div) 0v differential input large-signal step response 2 s/div v outdiff (1v/div) 1992 g28 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 4v Cv in = 2v c load = 0pf gain = 1 2.5v single-ended input large-signal step response 20 s/div v outdiff (1v/div) 1992 g29 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 4v Cv in = 2v gain = 1 c load = 10000pf c load = 1000pf 2.5v 1 s/div v outdiff (50mv/div) 1992 g30 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 50mv Cv in = 50mv c load = 0pf gain = 1 0v differential input small-signal step response 10 s/div v outdiff (50mv/div) 1992 g31 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 50mv Cv in = 50mv gain = 1 c load = 10000pf c load = 1000pf 0v typical perfor a ce characteristics uw
LTC1992 family 11 1992f applicable to the LTC1992 only. single-ended input small-signal step response 1 s/div v outdiff (50mv/div) 1992 g32 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 200mv Cv in = 100mv c load = 0pf gain = 1 2.5v single-ended input small-signal step response 10 s/div v outdiff (50mv/div) 1992 g33 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 200mv Cv in = 100mv gain = 1 c load = 10000pf c load = 1000pf 2.5v thd + noise vs frequency frequency (hz) 100 C100 thd + noise (db) C60 C50 C40 1k 10k 50k 1992 g34 C70 C80 C90 500khz measurement bandwidth +v s = 5v Cv s = C5v v ocm = 0v v out = 1v p-pdiff v out = 2v p-pdiff v out = 10v p-pdiff v out = 5v p-pdiff thd + noise vs amplitude input signal amplitude (v p-pdiff ) 0.1 C100 thd + noise (db) C90 C80 C70 C60 C40 11020 1992 g35 C50 500khz measurement bandwidth +v s = 5v Cv s = C5v v ocm = 0v 50khz 20khz 10khz 5khz 2khz 1khz typical perfor a ce characteristics uw differential noise voltage density vs frequency frequency (hz) input referred noise (nv hz) 1000 100 10 100 1000 10000 1922 g36 10 v ocm gain vs frequency, v s = 2.5v frequency (khz) 10 C15 gain (db) C5 5 100 1000 10000 1992 g19 C25 C20 C10 0 C30 C35 c load = 10pf to 10000pf
LTC1992 family 12 1992f applicable to the LTC1992-1 only. differential input differential gain vs frequency, v s = 2.5v single-ended input differential gain vs frequency, v s = 2.5v v ocm gain vs frequency frequency (khz) 10 C24 gain (db) C18 C12 C6 0 100 1000 10000 1992 g38 C30 C36 C42 C66 C60 C54 C48 6 12 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf frequency (khz) 10 C24 gain (db) C18 C12 C6 0 100 1000 10000 1992 g39 C30 C36 C42 C66 C60 C54 C48 6 12 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf differential gain error vs temperature differential phase response vs frequency differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage typical perfor a ce characteristics uw frequency (khz) 10 phase (deg) 0 C20 C40 C60 C80 C100 C120 C140 C160 C180 100 1000 1992 g40 c load = 10pf 50pf 100pf 500pf 1000pf 5000pf 10000pf temperature ( c) C50 gain error (%) 0.025 0.020 0.015 0.010 0.005 0 C 0.005 C 0.010 C 0.015 C 0.020 C 0.025 0 50 75 1992 g41 C25 25 100 125 frequency (khz) 10 C15 gain (db) C5 5 100 1000 10000 1992 g42 C25 C20 C10 0 C30 C35 c load = 10pf to 10000pf common mode voltage (v) 0 differential v os (mv) 1922 g43 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 5 4 3 2 1 0 C1 C2 C3 C4 C5 125 c C40 c 85 c 25 c +v s = 2.7v Cv s = 0v v ocm = 1.35v common mode voltage (v) 0 1922 g44 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 125 c C40 c 85 c 25 c differential v os (mv) 5 4 3 2 1 0 C1 C2 C3 C4 C5 +v s = 5v Cv s = 0v v ocm = 2.5v common mode voltage (v) C5 1922 g45 C4 C3 C2 C1 0 1 2 3 4 5 125 c C40 c 85 c 25 c differential v os (mv) 5 4 3 2 1 0 C1 C2 C3 C4 C5 +v s = 5v Cv s = C5v v ocm = 0v
LTC1992 family 13 1992f applicable to the LTC1992-1 only. differential input large-signal step response 2 s/div v outdiff (1v/div) 1992 g46 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 1.5v Cv in = 1.5v c load = 0pf 0v differential input large-signal step response 20 s/div v outdiff (1v/div) 1992 g47 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 1.5v Cv in = 1.5v c load = 10000pf c load = 1000pf 0v common mode rejection ratio vs frequency frequency (hz) 30 cmrr (db) 90 100 20 10 80 50 70 60 40 100 10k 100k 1m 1992 g48 0 1k ? v ampcm ? v ampdiff single-ended input large-signal step response power supply rejection ratio vs frequency 2 s/div v outdiff (1v/div) 1992 g49 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 4v Cv in = 2v c load = 0pf 2.5v single-ended input large-signal step response 20 s/div v outdiff (1v/div) 1992 g50 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 4v Cv in = 2v c load = 10000pf c load = 1000pf 2.5v frequency (hz) 10 40 psrr (db) 50 60 70 80 100 1k 10k 100k 1m 1992 g51 30 20 10 0 90 100 Cv s +v s ? v s ? v ampdiff differential input small-signal step response output balance vs frequency differential input small-signal step response 1 s/div v outdiff (50mv/div) 1992 g52 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 50mv Cv in = 50mv c load = 0pf 0v 10 s/div v outdiff (50mv/div) 1992 g53 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 50mv Cv in = 50mv c load = 10000pf c load = 1000pf 0v frequency (hz) 110 C40 output balance (db) C60 C80 100 1k 10k 100k 1m 1992 g54 C20 0 C100 ? v outcm ? v outdiff typical perfor a ce characteristics uw
LTC1992 family 14 1992f applicable to the LTC1992-1 only. single-ended input small-signal step response differential noise voltage density vs frequency thd + noise vs frequency thd + noise vs amplitude 1 s/div v outdiff (50mv/div) 1992 g55 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 200mv Cv in = 100mv c load = 0pf 2.5v single-ended input small-signal step response 10 s/div v outdiff (50mv/div) 1992 g56 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 200mv Cv in = 100mv c load = 10000pf c load = 1000pf 2.5v frequency (hz) 100 C100 thd + noise (db) C60 C50 C40 1k 10k 50k 1992 g58 C70 C80 C90 500khz measurement bandwidth +v s = 5v Cv s = C5v v ocm = 0v v out = 1v p-pdiff v out = 2v p-pdiff v out = 10v p-pdiff v out = 5v p-pdiff input signal amplitude (v p-pdiff ) 0.1 C100 thd + noise (db) C90 C80 C70 C60 C40 11020 1992 g59 C50 500khz measurement bandwidth +v s = 5v Cv s = C5v v ocm = 0v 50khz 20khz 10khz 5khz 2khz 1khz typical perfor a ce characteristics uw frequency (hz) 100 1000 10000 1922 g57 10 input referred noise (nv hz) 1000 100 10
LTC1992 family 15 1992f applicable to the LTC1992-2 only. differential input differential gain vs frequency, v s = 2.5v single-ended input differential gain vs frequency, v s = 2.5v v ocm gain vs frequency, v s = 2.5v differential gain error vs temperature differential phase response vs frequency differential input offset voltage vs input common mode voltage (note 7) differential input offset voltage vs input common mode voltage (note 7) differential input offset voltage vs input common mode voltage (note 7) frequency (khz) 10 C24 gain (db) C18 C12 C6 0 100 1000 10000 1992 g60 C30 C36 C42 C66 C60 C54 C48 6 18 12 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf frequency (khz) 10 C24 gain (db) C18 C12 C6 0 100 1000 10000 1992 g61 C30 C36 C42 C66 C60 C54 C48 6 18 12 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf typical perfor a ce characteristics uw common mode voltage (v) 0 differential v os (mv) 0 0.5 1.0 2.4 1992 g65 C0.5 C1.0 C2.0 0.6 1.2 1.8 0.3 2.7 0.9 1.5 2.1 C1.5 1.5 2.0 +v s = 2.7v Cv s = 0v v ocm = 1.35v C40 c 25 c 125 c 85 c common mode voltage (v) 0 differential v os (mv) 2.0 1.5 1.0 0.5 0 C0.5 C1.0 C1.5 C2.0 4.0 1992 g66 1.0 2.0 3.0 5.0 3.5 0.5 1.5 2.5 4.5 C40 c 125 c 25 c 85 c +v s = 5v Cv s = 0v v ocm = 2.5v common mode voltage (v) C5 differential v os (mv) 2.0 1.5 1.0 0.5 0 C0.5 C1.0 C1.5 C2.0 3 1992 g67 C3 C1 1 5 2 C4 C2 0 4 C40 c 125 c 25 c +v s = 5v Cv s = C5v v ocm = 0v 85 c frequency (khz) 10 C10 gain (db) C5 0 5 100 1000 10000 1992 g64 C15 C20 C25 C30 c load = 10pf to 10000pf frequency (khz) 10 phase (deg) 0 C20 C40 C60 C80 C 100 C 120 C 140 C 160 C 180 100 1000 1992 g62 c load = 10pf 50pf 100pf 500pf 1000pf 5000pf 10000pf temperature ( c) C50 gain error (%) 0.05 0.04 0.03 0.02 0.01 0 C 0.01 C 0.02 C 0.03 C 0.04 C 0.05 0 50 75 1992 g63 C25 25 100 125
LTC1992 family 16 1992f applicable to the LTC1992-2 only. differential input large-signal step response differential input large-signal step response common mode rejection ratio vs frequency (note 7) single-ended input large-signal step response power supply rejection ratio vs frequency (note 7) single-ended input large-signal step response differential input small-signal step response output balance vs frequency differential input small-signal step response 2 s/div 1992 g68 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 750mv Cv in = 750mv c load = 0pf v outdiff (1v/div) 0v typical perfor a ce characteristics uw 20 s/div 1992 g69 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 750mv Cv in = 750mv c load = 10000pf c load = 1000pf v outdiff (1v/div) 0v frequency (hz) 30 cmrr (db) 90 100 20 10 80 50 70 60 40 100 10k 100k 1m 1992 g70 0 1k ? v ampcm ? v ampdiff 2 s/div 1992 g71 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 2v Cv in = 1v c load = 0pf v outdiff (1v/div) 2.5v 20 s/div v outdiff (1v/div) 1992 g72 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 2v Cv in = 1v c load = 10000pf c load = 1000pf 2.5v frequency (hz) 10 40 psrr (db) 50 60 70 80 100 1k 10k 100k 1m 1992 g73 30 20 10 0 90 100 Cv s +v s ? v s ? v ampdiff 2 s/div v outdiff (50mv/div) 1992 g74 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 25mv Cv in = 25mv c load = 0pf 0v 20 s/div v outdiff (50mv/div) 1992 g75 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 25mv Cv in = 25mv c load = 10000pf c load = 1000pf 0v frequency (hz) 110 C40 output balance (db) C60 C80 100 1k 10k 100k 1m 1992 g76 C20 0 C 100 ? v outcm ? v outdiff
LTC1992 family 17 1992f applicable to the LTC1992-2 only. single-ended input small-signal step response differential noise voltage density vs frequency thd + noise vs frequency thd + noise vs amplitude single-ended input small-signal step response 2 s/div v outdiff (50mv/div) 1992 g77 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 100mv Cv in = 50mv c load = 0pf 2.5v typical perfor a ce characteristics uw 20 s/div v outdiff (50mv/div) 1992 g78 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 100mv Cv in = 50mv c load = 10000pf c load = 1000pf 2.5v frequency (hz) 100 C100 thd + noise (db) C60 C50 C40 1k 10k 50k 1992 g80 C70 C80 C90 v out = 1v p-pdiff v out = 2v p-pdiff v out = 10v p-pdiff v out = 5v p-pdiff input signal amplitude (v p-pdiff ) 0.1 C100 thd + noise (db) C90 C80 C70 C60 C40 110 1992 g81 C50 500khz measurement bandwidth +v s = 5v Cv s = C5v v ocm = 0v 50khz 20khz 10khz 5khz 2khz 1khz frequency (hz) 100 1000 10000 1922 g79 10 input referred noise (nv hz) 1000 100 10
LTC1992 family 18 1992f applicable to the LTC1992-5 only. differential input differential gain vs frequency, v s = 2.5v single-ended input differential gain vs frequency, v s = 2.5v v ocm gain vs frequency differential gain error vs temperature differential phase response vs frequency differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage typical perfor a ce characteristics uw frequency (khz) 10 C24 gain (db) C18 C12 C6 0 100 1000 10000 1992 g82 C30 C36 C42 C60 C54 C48 6 24 12 30 18 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf frequency (khz) 10 C24 gain (db) C18 C12 C6 0 100 1000 10000 1992 g83 C30 C36 C42 C60 C54 C48 6 24 12 30 18 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf frequency (khz) 10 phase (deg) 0 C20 C40 C60 C80 C100 C120 C140 C160 C180 100 1000 1992 g84 10pf 50pf 100pf 500pf 1000pf 5000pf 10000pf c load = temperature ( c) C50 gain error (%) 0.050 0.025 0 C 0.025 C 0.050 C 0.075 C 0.100 C 0.125 C01.50 0 50 75 1992 g85 C25 25 100 125 frequency (khz) 10 C10 gain (db) C5 0 5 100 1000 10000 1992 g86 C15 C20 C25 C30 c load = 10pf to 10000pf common mode voltage (v) 0 differential v os (mv) 1922 g87 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 2.0 1.5 1.0 0.5 0 C0.5 C1.0 C1.5 C2.0 125 c C40 c 85 c 25 c +v s = 2.7v Cv s = 0v v ocm = 1.35v common mode voltage (v) 0 1922 g88 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 125 c C40 c 85 c 25 c differential v os (mv) 2.0 1.5 1.0 0.5 0 C0.5 C1.0 C1.5 C2.0 +v s = 5v Cv s = 0v v ocm = 2.5v common mode voltage (v) C5 1922 g89 C4 C3 C2 C1 0 1 2 3 4 5 125 c C40 c 25 c 85 c differential v os (mv) 2.0 1.5 1.0 0.5 0 C0.5 C1.0 C1.5 C2.0 +v s = 5v Cv s = C5v v ocm = 0v
LTC1992 family 19 1992f applicable to the LTC1992-5 only. differential input large-signal step response differential input large-signal step response common mode rejection ratio vs frequency (note 7) single-ended input large-signal step response power supply rejection ratio vs frequency (note 7) single-ended input large-signal step response differential input small-signal step response output balance vs frequency differential input small-signal step response 2 s/div v outdiff (1v/div) 1992 g90 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 300mv Cv in = 300mv c load = 0pf 0v 20 s/div 1992 g91 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 300mv Cv in = 300mv c load = 10000pf c load = 1000pf v outdiff (1v/div) 0v frequency (hz) 30 cmrr (db) 90 100 20 10 80 50 70 60 40 100 10k 100k 1m 1992 g92 0 1k ? v ampcm ? v ampdiff 2 s/div v outdiff (1v/div) 1992 g93 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 800mv Cv in = 400mv c load = 0pf 2.5v 20 s/div 1992 g94 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 800mv Cv in = 400mv c load = 10000pf c load = 1000pf v outdiff (1v/div) 2.5v frequency (hz) 10 40 psrr (db) 50 60 70 80 100 10k 100k 1k 1m 1992 g95 30 20 10 0 90 100 +v s Cv s ? v s ? v ampdiff 5 s/div v outdiff (50mv/div) 1992 g96 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 10mv Cv in = 10mv c load = 0pf 0v 50 s/div v outdiff (50mv/div) 1992 g97 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 10mv Cv in = 10mv c load = 10000pf c load = 1000pf 0v frequency (hz) 110 C40 output balance (db) C60 C80 100 1k 10k 100k 1m 1992 g98 C20 0 C 100 ? v outcm ? v outdiff typical perfor a ce characteristics uw
LTC1992 family 20 1992f applicable to the LTC1992-5 only. single-ended input small-signal step response differential noise voltage density vs frequency thd + noise vs frequency thd + noise vs amplitude single-ended input small-signal step response 5 s/div v outdiff (50mv/div) 1992 g99 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 40mv Cv in = 20mv c load = 0pf 2.5v 50 s/div 1992 g100 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 40mv Cv in = 20mv c load = 10000pf c load = 1000pf v outdiff (50mv/div) 2.5v frequency (hz) 100 C100 thd + noise (db) C60 C50 C40 1k 10k 50k 1992 g102 C70 C80 C90 v out = 1v p-pdiff v out = 2v p-pdiff v out = 10v p-pdiff v out = 5v p-pdiff 500khz measurement bandwidth +v s = 5v Cv s = C5v v ocm = 0v input signal amplitude (v p-pdiff ) 0.1 C100 thd + noise (db) C90 C80 C70 C60 C40 15 1992 g103 C50 500khz measurement bandwidth +v s = 5v Cv s = C5v v ocm = 0v 50khz 20khz 10khz 5khz 2khz 1khz typical perfor a ce characteristics uw frequency (hz) 100 1000 10000 1922 g101 10 input referred noise (nv hz) 1000 100 10
LTC1992 family 21 1992f applicable to the LTC1992-10 only. differential input differential gain vs frequency, v s = 2.5v single-ended input differential gain vs frequency, v s = 2.5v v ocm gain vs frequency differential gain error vs temperature differential phase response vs frequency differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage frequency (khz) 10 C30 gain (db) C20 C10 0 10 100 1000 10000 1992 g104 C40 C50 C60 20 30 40 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf frequency (khz) 10 C30 gain (db) C20 C10 0 10 100 1000 10000 1992 g105 C40 C50 C60 20 30 40 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf frequency (khz) 10 C10 gain (db) C5 0 5 100 1000 10000 1992 g108 C15 C20 C25 C30 c load = 10pf to 10000pf typical perfor a ce characteristics uw frequency (khz) 10 phase (deg) 0 C20 C40 C60 C80 C100 C120 C140 C160 C180 100 1000 1992 g106 10pf 50pf 100pf 500pf 1000pf 5000pf 10000pf c load = temperature ( c) C50 gain error (%) 0.050 0.025 0 C 0.025 C 0.050 C 0.075 C 0.100 C 0.125 C 0.150 C 0.175 C 0.200 0 50 75 1992 g107 C25 25 100 125 common mode voltage (v) 0 1922 g109 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 125 c C40 c 85 c 25 c differential v os (mv) 2.0 1.5 1.0 0.5 0 C0.5 C1.0 C1.5 C2.0 +v s = 2.7v Cv s = 0v v ocm = 1.35v common mode voltage (v) 0 1922 g110 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 125 c C40 c 85 c 25 c differential v os (mv) 2.0 1.5 1.0 0.5 0 C0.5 C1.0 C1.5 C2.0 +v s = 5v Cv s = 0v v ocm = 2.5v common mode voltage (v) C5 1922 g111 C4 C3 C2 C1 0 1 2 3 4 5 125 c C40 c 85 c 25 c differential v os (mv) 2.0 1.5 1.0 0.5 0 C0.5 C1.0 C1.5 C2.0 +v s = 5v Cv s = C5v v ocm = 0v
LTC1992 family 22 1992f applicable to the LTC1992-10 only. differential input large-signal step response differential input large-signal step response common mode rejection ratio vs frequency (note 7) single-ended input large-signal step response power supply rejection ratio vs frequency (note 7) single-ended input large-signal step response differential input small-signal step response output balance vs frequency differential input small-signal step response 2 s/div 1992 g112 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 150mv Cv in = 150mv c load = 0pf v outdiff (1v/div) 0v 20 s/div v outdiff (1v/div) 1992 g113 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 150mv Cv in = 150mv c load = 10000pf c load = 1000pf 0v frequency (hz) 30 cmrr (db) 90 100 20 10 80 50 70 60 40 100 10k 100k 1m 1992 g114 0 1k ? v ampcm ? v ampdiff 2 s/div 1992 g115 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 400mv Cv in = 200mv c load = 0pf v outdiff (1v/div) 2.5v 20 s/div v outdiff (1v/div) 1992 g116 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 400mv Cv in = 200mv c load = 10000pf c load = 1000pf 2.5v frequency (hz) 10 40 psrr (db) 50 60 70 80 100 10k 100k 1k 1m 1992 g117 30 20 10 0 90 100 +v s Cv s ? v s ? v ampdiff 10 s/div 1992 g118 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 5mv Cv in = 5mv c load = 0pf v outdiff (50mv/div) 0v 100 s/div v outdiff (50mv/div) 1992 g119 +v s = 2.5v Cv s = C2.5v v ocm = 0v +v in = 5mv Cv in = 5mv c load = 10000pf c load = 1000pf 0v frequency (hz) 110 C60 output balance (db) 100 1k 10k 100k 1m 1992 g120 C40 C20 0 C80 C 100 C 120 ? v outcm ? v outdiff typical perfor a ce characteristics uw
LTC1992 family 23 1992f applicable to the LTC1992-10 only. single-ended input small-signal step response differential noise voltage density vs frequency thd + noise vs frequency thd + noise vs amplitude single-ended input small-signal step response 10 s/div 1992 g121 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 20mv Cv in = 10mv c load = 0pf v outdiff (50mv/div) 2.5v 100 s/div v outdiff (50mv/div) 1992 g122 +v s = 5v Cv s = 0v v ocm = 2.5v +v in = 0v to 20mv Cv in = 10mv c load = 10000pf c load = 1000pf 2.5v frequency (hz) 100 C100 thd + noise (db) C60 C50 C40 1k 10k 50k 1992 g124 C70 C80 C90 v out = 1v p-pdiff v out = 2v p-pdiff v out = 5v p-pdiff 500khz measurement bandwidth +v s = 5v Cv s = C5v v ocm = 0v input signal amplitude (v p-pdiff ) 0.1 C100 thd + noise (db) C90 C80 C70 C60 C40 12 1992 g125 C50 50khz 20khz 10khz 5khz 2khz 1khz typical perfor a ce characteristics uw frequency (hz) 100 1000 10000 1922 g123 10 input referred noise (nv hz) 1000 100 10
LTC1992 family 24 1992f ?n, +in (pins 1, 8): inverting and noninverting inputs of the amplifier. for the LTC1992 part, these pins are con- nected directly to the amplifiers p-channel mosfet input devices. the fixed gain LTC1992-x parts have precision, on-chip gain setting resistors. the input resistors are nominally 30k for the LTC1992-1, LTC1992-2 and LTC1992-5 parts. the input resistors are nominally 15k for the LTC1992-10 part. v ocm (pin 2): output common mode voltage set pin. the voltage on this pin sets the output signals common mode voltage level. the output common mode level is set independent of the input common mode level. this is a high impedance input and must be connected to a known and controlled voltage. it must never be left floating. +v s , v s (pins 3, 6): the +v s and Cv s power supply pins should be bypassed with 0.1 f capacitors to an adequate analog ground or ground plane. the bypass capacitors should be located as closely as possible to the supply pins. +out, out (pins 4, 5): the positive and negative outputs of the amplifier. these rail-to-rail outputs are designed to drive capacitive loads as high as 10,000pf. v mid (pin 7): mid-supply reference. this pin is connected to an on-chip resistive voltage divider to provide a mid- supply reference. this provides a convenient way to set the output common mode level at half-supply. if used for this purpose, pin 2 will be shorted to pin 7, pin 7 should be bypassed with a 0.1 f capacitor to ground. if this reference voltage is not used, leave the pin floating. uu u pi fu ctio s block diagra s w + C 1 7 2 6 3 8 5 4 + C 200k 200k +v s Cv s v + v C 30k 30k a1 + + + C a2 +out 1992 bd Cin v mid v ocm +in Cout +v s Cv s +v s Cv s (1992)
LTC1992 family 25 1992f block diagra s w (1992-x) C C + + +v s +v s Cin v mid +in Cv s +v s Cv s Cv s +out Cout v ocm 200k 200k r in r fb r in r fb 4 5 2 6 1 3 7 8 1992-x bd part LTC1992-1 LTC1992-2 LTC1992-5 LTC1992-10 r in 30k 30k 30k 15k r fb 30k 60k 150k 150k applicatio s i for atio wu uu theory of operation the LTC1992 family consists of five fully differential, low power amplifiers. the LTC1992 is an unconstrained fully differential amplifier. the LTC1992-1, LTC1992-2, LTC1992-5 and LTC1992-10 are fixed gain blocks (with gains of 1, 2, 5 and 10 respectively) featuring precision on- chip resistors for accurate and ultra stable gain. in many ways, a fully differential amplifier functions much like the familiar, ubiquitous op amp. however, there are several key areas where the two differ. referring to fig- ure 1, an op amp has a differential input, a high open-loop gain and utilizes negative feedback (through resistors) to set the closed-loop gain and thus control the amplifiers gain with great precision. a fully differential amplifier has all of these features plus an additional input and a comple- mentary output. the complementary output reacts to the input signal in the same manner as the other output, but in the opposite direction. two outputs changing in an equal but opposite manner require a common reference point (i.e., opposite relative to what?). the additional input, the v ocm pin, sets this reference point. the voltage on the v ocm input directly sets the output signals com- mon mode voltage and allows the output signals common mode voltage to be set completely independent of the input signals common mode voltage. uncoupling the input and output common mode voltages makes signal level shifting easy. for a better understanding of the operation of a fully differ- ential amplifier, refer to figure 2. here, the LTC1992 func- tional block diagram adds external resistors to realize a basic gain block. note that the LTC1992 functional block diagram is not an exact replica of the LTC1992 circuitry. however, the block diagram is correct and is a very good tool for understanding the operation of fully differential amplifier circuits. basic op amp fundamentals together with this block diagram provide all of the tools needed for understanding fully differential amplifier circuit applications. the LTC1992 block diagram has two op amps, two summing blocks (pay close attention the signs ) and four resistors. two resistors, r mid1 and r mid2 , connect di- rectly to the v mid pin and simply provide a convenient midsupply reference. its use is optional and it is not involved in the operation of the LTC1992s amplifier. the LTC1992 functions through the use of two servo networks
LTC1992 family 26 1992f applicatio s i for atio wu uu C C + + C C + + 1992 f01 r in r in r fb r fb fully differential amplifier with negative feedback fully differential amplifier Cv in +v in v ocm v ocm v ocm Cv out +v out C + r in r fb op amp with negative feedback v in v out r fb r in gain = C r fb r in gain = C +out ? differential input ? high open-loop gain ? differential output ?v ocm input sets output common mode level Cout Cin +in v ocm C + op amp out LTC1992 a o LTC1992 a o LTC1992 LTC1992 ? differential input ? high open-loop gain ? single-ended output Cin +in + C 7 2 6 3 + C r mid1 200k r mid2 200k inp inm v + v C r cmp 30k r cmm 30k a1 s p LTC1992 s m + + + C a2 +out 1992 f02 Cin +v in Cv in r in r fb r in v mid v ocm +in Cout Cv out +v out +v s Cv s 5 4 r fb 1 8 figure 1. comparison of an op amp and a fully differential amplifier figure 2. LTC1992 functional block diagram with external gain setting resistors
LTC1992 family 27 1992f each employing negative feedback and using an op amps differential input to create the servos summing junction. one servo controls the signal gain path. the differential input of op amp a1 creates the summing junction of this servo. any voltage present at the input of a1 is amplified (by the op amps large open-loop gain), sent to the summing blocks and then onto the outputs. taking note of the signs on the summing blocks, op amp a1s output moves +out and Cout in opposite directions. applying a voltage step at the inm node increases the +out voltage while the Cout volt- age decreases. the r fb resistors connect the outputs to the appropriate inputs establishing negative feedback and clos- ing the servos loop. any servo loop always attempts to drive its error voltage to zero. in this servo, the error voltage is the voltage between the inm and inp nodes, thus a1 will force the voltages on the inp and inm nodes to be equal (within the parts dc offset, open loop gain and bandwidth limits). the virtual short between the two inputs is con- ceptually the same as that for op amps and is critical to un- derstanding fully differential amplifier applications. the other servo controls the output common mode level. the differential input of op amp a2 creates the summing junction of this servo. similar to the signal gain servo above, any voltage present at the input of a2 is amplified, sent to the summing blocks and then onto the outputs. however, in this case, both outputs move in the same direction. the resistors r cmp and r cmm connect the +out and Cout outputs to a2s inverting input establishing negative feedback and closing the servos loop. the mid- point of resistors r cmp and r cmm derives the outputs common mode level (i.e., its average). this measure of the outputs common mode level connects to a2s inverting input while a2s noninverting input connects directly to the v ocm pin. a2 forces the voltages on its inverting and noninverting inputs to be equal. in other words, it forces the output common mode voltage to be equal to the voltage on the v ocm input pin. for any fully differential amplifier application to function properly both the signal gain servo and the common mode level servo must be satisfied. when analyzing an applica- tions circuit, the inp node voltage must equal the inm node voltage and the output common mode voltage must equal the v ocm voltage. if either of these servos is taken out of the specified areas of operation (e.g., inputs taken beyond the common mode range specifications, outputs hitting the supply rails or input signals varying faster than the part can track), the circuit will not function properly. fully differential amplifier signal conventions fully differential amplifiers have a multitude of signals and signal ranges to consider. to maintain proper operation with conventional op amps, the op amps inputs and its output must not hit the supply rails and the input signals common mode level must also be within the parts speci- fied limits. these considerations also apply to fully differ- ential amplifiers, but here there is an additional output to consider and common mode level shifting complicates matters. figure 3 provides a list of the many signals and specifications as well as the naming convention. the phrase common mode appears in many places and often leads to confusion. the fully differential amplifiers ability to uncouple input and output common mode levels yields great design flexibility, but also complicates matters some. for simplicity, the equations in figure 3 also assume an ideal amplifier and perfect resistor matching. for a de- tailed analysis, consult the fully differential amplifier appli- cations circuit analysis section.. basic applications circuits most fully differential amplifier applications circuits em- ploy symmetrical feedback networks and are familiar territory for op amp users. symmetrical feedback net- works require that the Cv in /+v out network is a mirror image duplicate of the +v in /Cv out network. each of these half circuits is basically just a standard inverting gain op amp circuit. figure 4 shows three basic inverting gain op amp circuits and their corresponding fully differential amplifier cousins. the vast majority of fully differential amplifier circuits derive from old tried and true inverting op amp circuits. to create a fully differential amplifier circuit from an inverting op amp circuit, first simply transfer the op amps v in /v out network to the fully differ- ential amplifiers Cv in /+v out nodes. then, take a mirror image duplicate of the network and apply it to the fully differential amplifiers +v in /Cv out nodes. op amp users can comfortably transfer any inverting op amp circuit to a fully differential amplifier in this manner. applicatio s i for atio wu uu
LTC1992 family 28 1992f C C + + 1992 f03 r in r in r fb v ocm v ocm r fb b b Cb Cb Cv in Ca Ca v incm v outcm v indiff 4av p-pdiff a a +v in 2av p-p 2av p-p = v indiff = +v in C Cv in 2bv p-p 2bv p-p differential input voltage = v incm = input common mode voltage +v out = ? ? + v ocm ; v oscm = 0v +v in C Cv in +v in + Cv in 2 = v outdiff = +v out C Cv out differential output voltage Cv out +v out LTC1992 v outdiff 4bv p-pdiff 1 2 r fb r in = v outcm = output common mode voltage +v out + Cv out 2 () Cv out = ? ? + v ocm ; v oscm = 0v Cv in C +v in 1 2 r fb r in v outdiff = v indiff ? r fb r in r n (0.13nv/ hz) v ampcm = v inp + v inm 2 cmrr = ; +v in = Cv in ? v ampcm ? v ampdiff output balance = ? v outcm ? v outdiff e nout = where: e nout = output referred noise voltage density e nin = input referred noise voltage density (resistive noise is already included in the specifications for the fixed gain LTC1992-x parts) + 1 r fb r in v outcm = v ocm v ampdiff = v inp C v inm v oscm = v outcm C v ocm () () v osdiffout = v osdiffin ? + 1 r fb r in () inm inp r in ? r fb r in + r fb () ? e nin 2 + r n 2 applicatio s i for atio wu uu figure 3. fully differential amplifier signal conventions (ideal amplifier and perfect resistor matching is assumed) single-ended to differential conversion one of the most important applications of fully differen- tial amplifiers is single-ended signaling to differential signaling conversion. many systems have a single-ended signal that must connect to an adc with a differential input. the adc could be run in a single-ended manner, but performance usually degrades. fortunately, all of basic applications circuits shown in figure 4, as well as all of the fixed gain LTC1992-x parts, are equally suitable for both differential and single-ended input signals. for single-ended input signals, connect one of the inputs to a reference voltage (e.g., ground or midsupply) and connect the other to the signal path. there are no tradeoffs here as the parts performance is the same with single- ended or differential input signals. which input is used for the signal path only affects the polarity of the differ- ential output signal. signal level shifting another important application of fully differential amplifier is signal level shifting. single-ended to differential conver- sion accompanied by a signal level shift is very common- place when driving adcs. as noted in the theory of operation section, fully differential amplifiers have a com- mon mode level servo that determines the output common mode level independent of the input common mode level. to set the output common mode level, simply apply the desired voltage to the v ocm input pin. the voltage range on the v ocm pin is from (Cv s + 0.5v) to (+v s C 1.3v).
LTC1992 family 29 1992f C C + + r in r in r fb r fb gain block Cv in +v in v ocm Cv out +v out C + r in v in r fb v out r fb r in gain = LTC1992 C C + + r in r in r fb r fb ac coupled gain block Cv in +v in v ocm Cv out +v out C + r in c in c in c in v in r fb v out LTC1992 C C + + r in r in r fb r fb single pole lowpass filter Cv in +v in r fb r in p s + p ; p = v ocm Cv out +v out C + r in v in r fb c v out h (s) = h o ? where h o = LTC1992 c c 1 r fb ? c C C + + r1 r3 r3 r4 r4 r1 r2 r2 3-pole lowpass filter Cv in +v in r2 r1 ; p =; o = v ocm Cv out 1992 f04 +v out C + r1 r3 r4 r2 c1 c2 v out where h o = LTC1992 c3 c1 c1 1 r4c3 1 r2r3c1c2 c2 2 c3 2 p s + p h (s) = h o () o 2 s 2 + s + o q o 2 () v in r fb r in ; p = h o = 1 r in ? c in s s + p h (s) = h o ? c2 c1 r1 ? r2r3 r1 r2 + r1 r2 + r2 r3 ? q = applicatio s i for atio wu uu figure 4. basic fully differential amplifier application circuits (note: single-ended to differential conversion is easily accomplished by connecting one of the input nodes, +v in or ? in , to a dc reference level (e.g., ground))
LTC1992 family 30 1992f applicatio s i for atio wu uu the v ocm input pin has a very high input impedance and is easily driven by even the weakest of sources. many adcs provide a voltage reference output that defines either its common mode level or its full-scale level. apply the adcs reference potential either directly to the v ocm pin or through a resistive voltage divider depending on the reference voltages definition. when controlling the v ocm pin by a high impedance source, connect a bypass capaci- tor (1000pf to 0.1 f) from the v ocm pin to ground to lower the high frequency impedance and limit external noise coupling. other applications will want the output biased at a midpoint of the power supplies for maximum output voltage swing. for these applications, the LTC1992 pro- vides a midsupply potential at the v mid pin. the v mid pin connects to a simple resistive voltage divider with two 200k resistors connected between the supply pins. to use this feature, connect the v mid pin to the v ocm pin and bypass this node with a capacitor. one undesired effect of utilizing the level shifting function is an increase in the differential output offset voltage due to gain setting resistor mismatch. the offset is approxi- mately the amount of level shift (v outcm C v incm ) multi- plied by the amount of resistor mismatch. for example, a 2v level shift with 0.1% resistors will give around 2mv of output offset (2 ? 0.1% = 2mv). the exact amount of offset is dependent on the applications gain and the resistor mismatch. for a detail description, consult the fully differ- ential amplifier applications circuit analysis section. cmrr and output balance one common misconception of fully differential amplifiers is that the common mode level servo guarantees an infinite common mode rejection ratio (cmrr). this is not true. the common mode level servo does, however, force the two outputs to be truly complementary (i.e., exactly opposite or 180 degrees out of phase). output balance is a measure of how complementary the two outputs are. at low frequencies, cmrr is primarily determined by the matching of the gain setting resistors. like any op amp, the LTC1992 does not have infinite cmrr, however resis- tor mismatching of only 0.018%, halves the circuits cmrr. standard 1% tolerance resistors yield a cmrr of about 40db. for most applications, resistor matching dominates low frequency cmrr performance. the speci- fications for the fixed gain LTC1992-x parts include the on-chip resistor matching effects. also, note that an input common mode signal appears as a differential output signal reduced by the cmrr. as with op amps, at higher frequencies the cmrr degrades. refer to the typical performance plots for the details of the cmrr perfor- mance over frequency. at low frequencies, the output balance specification is determined by the matching of the on-chip r cmm and r cmp resistors. at higher frequencies, the output balance degrades. refer to the typical performance plots for the details of the output balance performance over frequency. input impedance the input impedance for a fully differential amplifier appli- cation circuit is similar to that of a standard op amp inverting amplifier. one major difference is that the input impedance is different for differential input signals and single-ended signals. referring to figure 3, for differential input signals the input impedance is expressed by the following expression: r indiff = 2 ? r in for single-ended signals, the input impedance is ex- pressed by the following expression: r r r rr ins in fb in fb -e = + () 1 2 C ? the input impedance for single-ended signals is slightly higher than the r in value since some of the input signal is fed back and appears as the amplifiers input common mode level. this small amount of positive feedback in- creases the input impedance. driving capacitive loads the LTC1992 family of parts is stable for all capacitive loads up to at least 10,000pf. while stability is guaranteed, the parts performance is not unaffected by capacitive loading. large capacitive loads increase output step re- sponse ringing and settling time, decrease the bandwidth
LTC1992 family 31 1992f applicatio s i for atio wu uu and increase the frequency response peaking. refer to the typical performance plots for small-signal step response, large-signal step response and gain over frequency to appraise the effects of capacitive loading. while the con- sequences are minor in most instances, consider these effects when designing application circuits with large capacitive loads. input signal amplitude considerations for application circuits to operate correctly, the amplifier must be in its linear operating range. to be in the linear operating range, the input signals common mode voltage must be within the parts specified limits and the rail-to- rail outputs must stay within the supply voltage rails. additionally, the fixed gain LTC1992-x parts have input protection diodes that limit the input signal to be within the supply voltage rails. the unconstrained LTC1992 uses external resistors allowing the source signals to go be- yond the supply voltage rails. when taken outside of the linear operating range, the circuit does not perform as expected, however nothing extreme occurs. outputs driven into the supply voltage rails are simply clipped. there is no phase reversal or oscillation. once the outputs return to the linear operating range, there is a small recovery time, then normal opera- tion proceeds. when the input common mode voltage is below the specified lower limit, on-chip protection diodes conduct and clamp the signal. once the signal returns to the specified operating range, normal operation proceeds. if the input common mode voltage goes slightly above the specified upper limit (by no more than about 500mv), the amplifiers open-loop gain reduces and dc offset and closed-loop gain errors increase. return the input back to the specified range and normal performance commences. if taken well above the upper limit, the amplifiers input stage is cut off. the gain servo is now open loop; however, the common mode servo is still functional. output balance is maintained and the outputs go to opposite supply rails. however, which output goes to which supply rail is random. once the input returns to the specified input common mode range, there is a small recovery time then normal operation proceeds. the LTC1992s input signal common mode range (v incmr ) is from (Cv s C 0.1v) to (+v s C 1.3v). this specification applies to the voltage at the amplifier? input, the inp and inm nodes of figure 2. the specifications for the fixed gain LTC1992-x parts reflect a higher maximum limit as this specification is for the entire gain block and references the signal at the input resistors. differential input signals and single-ended signals require a slightly different set of formulae. differential signals separate very nicely into common mode and differential components while single ended signals do not. refer to figure 5 for the formulae for calculating the available signal range. additionally, table 1 lists some common configurations and their appropriate signal levels. the LTC1992s outputs allow rail-to-rail signal swings. the output voltage on either output is a function of the input signals amplitude, the gain configured and the output signals common mode level set by the v ocm pin. for maximum signal swing, the v ocm pin is set at the midpoint of the supply voltages. for other applications, such as an adc driver, the required level must fall within the v ocm range of (Cv s + 0.5v) to (+v s C 1.3v). for single- ended input signals, it is not always obvious which output will clip first thus both outputs are calculated and the minimum value determines the signal limit. refer to figure 5 for the formulae and table 1 for examples. to ensure proper linear operation both the input common mode level and the output signal level must be within the specified limits. these same criteria are also present with standard op amps. however, with a fully differential ampli- fier, it is a bit more complex and old familiar op amp intuition often leads to the wrong result. this is especially true for single-ended to differential conversion with level shifting. the required calculations are a bit tedious, but are necessary to guarantee proper linear operation.
LTC1992 family 32 1992f applicatio s i for atio wu uu C C + + r in inm node inp node r in r fb v ocm v ocm a. calculate v incm minimum and maximum given r in , r fb and v ocm v incm(max) = (+v s C 1.3v) + (+v s C 1.3v C v ocm ) v incm(min) = (Cv s C 0.1v) + (Cv s C 0.1v C v ocm ) b. with a known v incm , r in , r fb and v ocm , calculate common mode voltage at inp and inm nodes (v incm(amp) ) and check that it is within the specified limits. v incm(amp) = = v incm + v ocm r fb b b Cb Cb Cv in Ca Ca v incm v outcm v indiff 4av p-pdiff a a +v in 2av p-p 2av p-p 2bv p-p 2bv p-p Cv out +v out LTC1992 v outdiff 4bv p-pdiff 1 g 1 g 4 g 4 g v inp + v inm 2 g g + 1 1 g + 1 differential input signals C C + + 1992 f05 r in inm node inp node r in r fb v ocm v ocm r fb b b Cb Cb v inref Ca v outcm v ref a v insig 2av p-p 2bv p-p 2bv p-p Cv out +v out LTC1992 v outdiff 4bv p-pdiff single end input signals input common mode limits output signal clipping limit input common mode limits (note: for the fixed gain LTC1992-x parts, v inref and v insig cannot exceed the supplies) output signal clipping limit or or v indiff(max) (v p-pdiff ) = the lesser value of (+v s C v ocm ) or (v ocm C Cv s ) v inref 2 1 g v insig(max) = 2 v insig(max) = the lesser value of v inref + (+v s C v ocm ) or v inref + (v ocm C Cv s ) +v s C 1.3v C +v s C 1.3v C v ocm + (( )) v inref 2 1 g v insig(min) = 2 Cv s C 0.1v C Cv s C 0.1v C v ocm + (( )) 1 g 2 g 2 g v insig(min) = the greater value of v inref + (Cv s C v ocm ) or v inref + (v ocm C +v s ) 2 g 2 g v insigp-p = 2 (+v s C Cv s ) C 1.2v (+v s C Cv s ) C 1.2v + (( )) r fb r in g = r fb r in g = figure 5. input signal limitations
LTC1992 family 33 1992f applicatio s i for atio wu uu table 1. input signal limitations for some common applications differential input signal, v ocm at midsupply . (v incm must be within the min and max table values and v indiff must be less than the table value) +v s ? s gain v ocm v incm(max) v incm(min) v indiff(max) v outdiff(max) (v) (v) (v/v) (v) (v) (v) (v p-pdiff )(v p-pdiff ) 2.7 0 1 1.35 1.450 C1.550 5.40 5.40 2.7 0 2 1.35 1.425 C0.825 2.70 5.40 2.7 0 5 1.35 1.410 C0.390 1.08 5.40 2.7 0 10 1.35 1.405 C0.245 0.54 5.40 5 0 1 2.5 4.900 C2.700 10.00 10.00 5 0 2 2.5 4.300 C1.400 5.00 10.00 5 0 5 2.5 3.940 C0.620 2.00 10.00 5 0 10 2.5 3.820 C0.360 1.00 10.00 5 C5 1 0 7.400 C10.200 20.00 20.00 5 C5 2 0 5.550 C7.650 10.00 20.00 5 C5 5 0 4.440 C6.120 4.00 20.00 5 C5 10 0 4.070 C5.610 2.00 20.00 differential input signal, v ocm at typical adc levels . (v incm must be within the min and max table values and v indiff must be less than the table value) +v s ? s gain v ocm v incm(max) v incm(min) v indiff(max) v outdiff(max) (v) (v) (v/v) (v) (v) (v) (v p-pdiff )(v p-pdiff ) 2.7 0 1 1 1.800 C1.200 4.00 4.00 2.7 0 2 1 1.600 C0.650 2.00 4.00 2.7 0 5 1 1.480 C0.320 0.80 4.00 2.7 0 10 1 1.440 C0.210 0.40 4.00 5 0 1 2 5.400 C2.200 8.00 8.00 5 0 2 2 4.550 C1.150 4.00 8.00 5 0 5 2 4.040 C0.520 1.60 8.00 5 0 10 2 3.870 C0.310 0.80 8.00 5 C5 1 2 5.400 C12.200 12.00 12.00 5 C5 2 2 4.550 C8.650 6.00 12.00 5 C5 5 2 4.040 C6.520 2.40 12.00 5 C5 10 2 3.870 C5.810 1.20 12.00
LTC1992 family 34 1992f applicatio s i for atio wu uu table 1. input signal limitations for some common applications +v s ? s gain v ocm v inref v insig(max) v insig(min) v insigp-p(max) v outdiff(max) (v) (v) (v/v) (v) (v) (v) (v) (v p-p around v inref )(v p-pdiff ) 2.7 0 1 1.35 1.35 1.550 C1.350 0.40 0.40 2.7 0 2 1.35 1.35 1.500 0.000 0.30 0.60 2.7 0 5 1.35 1.35 1.470 0.810 0.24 1.20 2.7 0 10 1.35 1.35 1.460 1.080 0.22 2.20 5 0 1 2.5 2.5 7.300 C2.500 9.60 9.60 5 0 2 2.5 2.5 5.000 0.000 5.00 10.00 5 0 5 2.5 2.5 3.500 1.500 2.00 10.00 5 0 10 2.5 2.5 3.000 2.000 1.00 10.00 5 C5 1 0 0 10.000 C10.000 20.00 20.00 5 C5 2 0 0 5.000 C5.000 10.00 20.00 5 C5 5 0 0 2.000 C2.000 4.00 20.00 5 C5 10 0 0 1.000 C1.000 2.00 20.00 midsupply referenced single-ended input signal, v ocm at midsupply . (the v insig min and max values listed account for both the input common mode limits and the output clipping) +v s ? s gain v ocm v inref v insig(max) v insig(min) v insigp-p(max) v outdiff(max) (v) (v) (v/v) (v) (v) (v) (v) (v p-p around v inref )(v p-pdiff ) 2.7 0 1 1 1.35 2.250 C0.650 1.80 1.80 2.7 0 2 1 1.35 1.850 0.350 1.00 2.00 2.7 0 5 1 1.35 1.610 0.950 0.52 2.60 2.7 0 10 1 1.35 1.530 1.150 0.36 3.60 5 0 1 2 2.5 6.500 C1.500 8.00 8.00 5 0 2 2 2.5 4.500 0.500 4.00 8.00 5 0 5 2 2.5 3.300 1.700 1.60 8.00 5 0 10 2 2.5 2.900 2.100 0.80 8.00 5 C5 1 2 0 6.000 C6.000 12.00 12.00 5 C5 2 2 0 3.000 C3.000 6.00 12.00 5 C5 5 2 0 1.200 C1.200 2.40 12.00 5 C5 10 2 0 0.600 C0.600 1.20 12.00 midsupply referenced single-ended input signal, v ocm at typical adc levels . (the v insig min and max values listed account for both the input common mode limits and the output clipping)
LTC1992 family 35 1992f applicatio s i for atio wu uu table 1. input signal limitations for some common applications +v s ? s gain v ocm v inref v insig(max) v insig(min) v insigp-p(max) v outdiff(max) (v) (v) (v/v) (v) (v) (v) (v) (v p-p around v inref )(v p-pdiff ) 2.7 0 1 1.35 0 2.700 C2.700 5.40 5.40 2.7 0 2 1.35 0 1.350 C1.350 2.70 5.40 2.7 0 5 1.35 0 0.540 C0.540 1.08 5.40 2.7 0 10 1.35 0 0.270 C0.270 0.54 5.40 5 0 1 2.5 0 5.000 C5.000 10.00 10.00 5 0 2 2.5 0 2.500 C2.500 5.00 10.00 5 0 5 2.5 0 1.000 C1.000 2.00 10.00 5 0 10 2.5 0 0.500 C0.500 1.00 10.00 single supply ground referenced single-ended input signal, v ocm at midsupply . (the v insig min and max values listed account for both the input common mode limits and the output clipping) +v s ? s gain v ocm v inref v insig(max) v insig(min) v insigp-p(max) v outdiff(max) (v) (v) (v/v) (v) (v) (v) (v) (v p-p around v inref )(v p-pdiff ) 2.7 0 1 1 0 2.000 C2.000 4.00 4.00 2.7 0 2 1 0 1.000 C1.000 2.00 4.00 2.7 0 5 1 0 0.400 C0.400 0.80 4.00 2.7 0 10 1 0 0.200 C0.200 0.40 4.00 5 0 1 2 0 4.000 C4.000 8.00 8.00 5 0 2 2 0 2.000 C2.000 4.00 8.00 5 0 5 2 0 0.800 C0.800 1.60 8.00 5 0 10 2 0 0.400 C0.400 0.80 8.00 single supply ground referenced single-ended input signal, v ocm at typical adc reference levels . (the v insig min and max values listed account for both the input common mode limits and the output clipping) fully differential amplifier applications circuit analysis all of the previous applications circuit discussions have assumed perfectly matched symmetrical feedback net- works. to consider the effects of mismatched or asym- metrical feedback networks, the equations get a bit messier. figure 6 lists the basic gain equation for the differential output voltage in terms of +v in , Cv in , v osdiff , v outcm and the feedback factors 1 and 2. the feedback factors are simply the portion of the output that is fed back to the input summing junction by the r fb -r in resistive voltage divider. 1 and 2 have the range of zero to one. the v outcm term also includes its offset voltage, v oscm , and its gain mis- match term, k cm . the k cm term is determined by the matching of the on-chip r cmp and r cmm resistors in the common mode level servo (see figure 2). while mathematically correct, the basic signal equation does not immediately yield any intuitive feel for fully differential amplifier application operation. however, by nulling out specific terms, some basic observations and sensitivities come forth. setting 1 equal to 2, v osdiff to zero and v outcm to v ocm gives the old gain equation from figure 3. the ground referenced, single-ended input sig- nal equation yields the interesting result that the driven side feedback factor ( 1) has a very different sensitivity than the grounded side ( 2). the cmrr is twice the feedback factor difference divided by the feedback factor sum. the differential output offset voltage has two terms. the first term is determined by the input offset term, v osdiff , and the applications gain. note that this term equates to the formula in figure 3 when 1 equals 2. the amount of signal level shifting and the feedback factor mismatch determines the second term. this term
LTC1992 family 36 1992f applicatio s i for atio wu uu quantifies the undesired effect of signal level shifting discussed earlier in the signal level shifting section. asymmetrical feedback application circuits the basic signal equation in figure 6 also gives insight to another piece of intuition. the feedback factors may be deliberately set to different values. one interesting class of these application circuits sets one or both of the feedback factors to the extreme values of either zero or one. figure 7 shows three such circuits. at first these application circuits may look to be unstable or open loop. it is the common mode feedback loop that enables these circuits to function. while they are useful circuits, they have some shortcomings that must be considered. first, do to the severe feedback factor asym- metry, the v ocm level influences the differential output voltage with about the same strength as the input signal. with this much gain in the v ocm path, differential output offset and noise increase. the large v ocm to v outdiff gain also necessitates that these circuits are largely limited to C C + + r in2 r in1 2[+v in ? (1 C 1) C (Cv in ) ? (1 C 2)] + 2v osdiff + 2v outcm ( 1 C 2) 1 + 2 r fb1 v ocm v ocm v outdiff = where: ? for ground referenced, single-ended input signal, let +v in = v insig and Cv in = 0v r fb2 Cv in v indiff +v in C Cv in +v in Cv out +v out LTC1992 v outdiff +v out C Cv out 2 ? v insig ? (1 C 1) + 2v osdiff + 2v outcm ( 1 C 2) 1 + 2 v outdiff = ? common mode rejection: set +v in = Cv in = v incm , v osdiff = 0v, v outcm = 0v ? v incm ? v outdiff cmrr = = 2 ; output referred 1 + 2 2 C 1 2 C 1 1 + 2 ? output dc offset voltage: set +v in = Cv in = v incm v osdiffout = v osdiff + (v outcm C v incm ) 2 2 1 + 2 r in1 r in1 + r fb1 1 = ; 2 = ; v osdiff = amplifier input referred offset voltage v outcm = k cm ? v ocm + v oscm 0.999 < k cm < 1.001 r in2 r in2 + r fb2 figure 6. basic equations for mismatched or asymmetrical feedback applications circuits dual, split supply voltage applications with a ground referenced input signal and a grounded v ocm pin. the top application circuit in figure 7 yields a high input impedance, precision gain of 2 block without any external resistors. the on-chip common mode feedback servo resistors determine the gain precision (better than 0.1 percent). by using the Cv out output alone, this circuit is also useful to get a precision, single-ended output, high input impedance inverter. to intuitively understand this circuit, consider it as a standard op amp voltage follower (delivered through the signal gain servo) with a comple- mentary output (delivered through the common mode level servo). as usual, the amplifiers input common mode range must not be exceeded. as with a standard op amp voltage follower, the common mode signal seen at the amplifiers input is the input signal itself. this condi- tion limits the input signal swing, as well as the output signal swing, to be the input signal common mode range specification. the middle circuit is largely the same as the first except that the noninverting amplifier path has gain. note that
LTC1992 family 37 1992f applicatio s i for atio wu uu once the v ocm voltage is set to zero, the gain formula is the same as a standard noninverting op amp circuit multiplied by two to account for the complementary output. taking r fb to zero (i.e., taking to one) gives the same formula as the top circuit. as in the top circuit, this circuit is also useful as a single-ended output, high input impedance inverting gain block (this time with gain). the input common mode considerations are similar to the top circuits, but are not nearly as constrained since there is now gain in the noninverting amplifier path. this circuit, with v ocm at ground, also permits a rail-to-rail output swing in most applications. C C + + +v out v outdiff = 2(+v in C v ocm ) setting v ocm = 0v v outdiff = 2v in Cv out v in v ocm v ocm LTC1992 C C + + +v out r fb r in v outdiff = 2 setting v ocm = 0v v outdiff = 2v in Cv out v in v ocm r in r fb () +v in ; = = 2v in 1 + C v ocm 1 () 1 () r in r in + r fb r fb r in C C + + +v out v outdiff = 2 setting v ocm = 0v v outdiff = 2v in Cv out 1992 f07 v in v ocm () +v in ; = = 2v in + v ocm 1 C () 1 C () r in r in + r fb r fb r in v ocm LTC1992 v ocm LTC1992 figure 7. asymmetrical feedback application circuits (most suitable in applications with dual, split supplies (e.g., 5v), ground referenced single-ended input signals and v ocm connected to ground) the bottom circuit is another circuit that utilizes a standard op amp configuration with a complementary output. in this case, the standard op amp circuit has an inverting configuration. with v ocm at zero volts, the gain formula is the same as a standard inverting op amp circuit multiplied by two to account for the complementary output. this circuit does not have any common mode level constraints as the inverting input voltage sets the input common mode level. this circuit also delivers rail-to-rail output voltage swing without any concerns.
LTC1992 family 38 1992f typical applicatio s u C C + + LTC1992 3 6 v ocm v mid 0.1 f 100pf 7 6 5 13.3k 40k 4 5 2 7 8 1 10k 10k 5v 13.3k 40k 5v 10k 10k 100 ? 100 ? 0.1 f +in v ref v cc 2 18 3 4 1992 ta02a Cin 1 f sck sdo conv ltc1864 serial data link gnd 0v v in 2.5v C2.5v interfacing a bipolar, ground referenced, single-ended signal to a unipolar single supply, differential input adc (v in = 0v gives a digital mid-scale code) C C + + LTC1992-2 3 6 v ocm v mid 0.1 f 100pf 7 6 5 4 5 2 7 8 1 100 ? 5v 100 ? 0.1 f +in v ref v cc 2 18 3 4 1992 ta03a Cin 1 f sck sdo conv ltc1864 serial data link gnd v in 2.5v 0v compact, unipolar serial data conversion C C + + v1 = v b + v c C v a v2 = v b + v a C v c v a 1 4 0.1 f 3 +v s Cv s 6 5 2 8 v c v b v ocm LTC1992-2 0.1 f 1992 ta04 zero components, single-ended adder/subtracter
LTC1992 family 39 1992f typical applicatio s u u package descriptio ms8 package 8-lead plastic msop (reference ltc dwg # 05-08-1660) msop (ms8) 0603 0.53 0.152 (.021 .006) seating plane note: 1. dimensions in millimeter/(inch) 2. drawing not to scale 3. dimension does not include mold flash, protrusions or gate burrs. mold flash, protrusions or gate burrs shall not exceed 0.152mm (.006") per side 0.18 (.007) 0.254 (.010) 1.10 (.043) max 0.22 C 0.38 (.009 C .015) typ 0.127 0.076 (.005 .003) 0.86 (.034) ref 0.65 (.0256) bsc 0 C 6 typ detail a detail a gauge plane 12 3 4 4.90 0.152 (.193 .006) 8 7 6 5 3.00 0.102 (.118 .004) (note 3) 3.00 0.102 (.118 .004) (note 4) 0.52 (.0205) ref 5.23 (.206) min 3.20 C 3.45 (.126 C .136) 0.889 0.127 (.035 .005) recommended solder pad layout 0.42 0.038 (.0165 .0015) typ 0.65 (.0256) bsc 4. dimension does not include interlead flash or protrusions. interlead flash or protrusions shall not exceed 0.152mm (.006") per side 5. lead coplanarity (bottom of leads after forming) shall be 0.102mm (.004") max 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 represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. single-ended to differential conversion driving an adc 2.2 f 10 f 10 f 10 ? 47 f 4 6 refcomp 4.375v control logic and timing b15 to b0 16-bit sampling adc C + 10 f 5v or 3v p control lines d15 to d0 output buffers 16-bit parallel bus 11 to 26 1992 ta06a ognd ov dd 28 29 1 2 a in + a in C shdn cs convst rd busy 33 32 31 30 27 ltc1603 3 36 35 10 9 5v 5v av dd av dd 7.5k dv dd dgnd v ref 8 agnd agnd 7 agnd 5 agnd 34 C5v v ss 10 f 2.5v ref 10 f 1.75x + + + + + + C C + + 5v C5v LTC1992-1 3 6 v ocm v mid v in 100pf 4 5 2 7 8 1 100 ? 100 ? 0.1 f 0.1 f snr =85.3db thd = C72.1db sinad = C72db f in = 10.0099khz f sample = 333khz 0 C10 C20 C30 C40 C50 C60 C70 C80 C90 C100 C110 C120 C130 C140 frequency (khz) 0 amplitude (db) 80 70 1992 ta06b 20 10 40 30 60 50 100 90 fft of the output data
LTC1992 family 40 1992f linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com ? linear technology corporation 2005 lt/tp 0105 1k ? printed in usa related parts part number description comments lt1167 precision instrumentation amplifier single resistor sets the gain lt1990 high voltage, gain selectable difference amplifier 250v common mode, micropower, selectable gain = 1, 10 lt1991 precision gain selectable difference amplifier micropower, pin selectable gain = C13 to 14 lt1995 high speed gain selectable difference amplifier 30mhz, 1000v/ s, pin selectable gain = C7 to 8 lt6600-x differential in/out amplifier lowpass filter very low noise, standard differential amplifier pinout typical applicatio u bnc v inp C C + + 1 4 7 8 11 4 12 17 13 14 16 0.1 f v + 1/2 ltc1043 3 5v C5v 6 5 2 8 v ocm 7 bnc v inp v ocm v mid LTC1992 0.1 f 0.1 f clk v C 0.1 f 1992 ta05a 0.1 f clk 0.1 f C C + + 1 4 3 6 5 2 8 v ocm 7 v mid LTC1992 bnc v outm bnc v outp 60khz low pass filter sampler 2khz lowpass filter 9.53k 9.53k 9.53k 37.4k 60.4k 37.4k 60.4k 9.53k 8.87k 8.87k 75k 75k 120pf 120pf 390pf 390pf 330pf 180pf 0.1 f 10k balanced frequency converter (suitable for frequencies up to 50khz) 0v 0v 0v 0v 200 s/div v inp = 24khz (1v/div) v outp = 1khz (0.5v/div) v outm = 1khz (0.5v/div) clk = 25khz (logic square wave) (5v/div) 1992 ta05b

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