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lt 1028/ lt 1128 1 1028fd for more information www.linear.com/lt1028 typical application features description ultralow noise precision high speed op amps the lt ? 1028 (gain of C1 stable)/lt1128(gain of +1 stable) achieve a new standard of excellence in noise performance with 0.85 nv/ hz 1 khz noise , 1.0 nv/ hz 10 hz noise. this ultralow noise is combined with excellent high speed specifications ( gain - bandwidth product is 75 mhz for lt1028 , 20 mhz for lt1128), distortion-free output, and true precision parameters (0.1 v/c drift , 10 v offset voltage , 30 million voltage gain). although the lt1028/ lt1128 input stage operates at nearly 1 ma of collector current to achieve low voltage noise, input bias current is only 25na. the lt1028/lt1128s voltage noise is less than the noise of a 50 resistor. therefore, even in very low source impedance transducer or audio amplifier applications, the lt1028/lt1128s contribution to total system noise will be negligible. l , lt , lt c , lt m , linear technology and the linear logo are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. ultralow noise 1m tia photodiode amplifier applications n voltage noise 1.1 nv/ hz max at 1khz 0.85 nv/ hz typ at 1khz 1.0 nv/ hz typ at 10hz 35 nv p-p typ , 0.1hz to 10hz n voltage and current noise 100% tested n gain-bandwidth product lt1028: 50mhz min lt1128: 13mhz min n slew rate lt1028: 11v/s min lt1128: 5v/s min n offset voltage: 40v max n drift with temperature: 0.8v/c max n voltage gain: 7 million min n available in 8-lead so package n low noise frequency synthesizers n high quality audio n infrared detectors n accelerometer and gyro amplifiers n 350 bridge signal conditioning n magnetic search coil amplifiers n hydrophone amplifiers voltage noise vs frequency frequency (hz) 1 0.1 1 10 10 100 1028 ta02 voltage noise density (nv/ hz ) 0.1 1k 1/f corner = 3.5hz 1/f corner = 14hz typical maximum v s = 15v t a = 25c + C v out = ~0.4v + i pd ? 1m v s C v s C v s + lt1028 0.1f jfetnxp bf862 photodiode sfh213 d s 4.32k 1028 ta01 1m 0.5pf 4.99k v s = 15v downloaded from: http:///
lt 1028/ lt 1128 2 1028fd for more information www.linear.com/lt1028 absolute maximum ratings supply voltage C55 c to 105 c .................................................. 22 v 105 c to 125 c .................................................. 16 v differential input current ( note 9) ....................... 25 ma input voltage .............................. equal to supply voltage output short - circuit duration .......................... indefinite (note 1) top view v + v os trim Cin out over-comp +in v C (case) 8 7 5 3 2 1 4 h package 8-lead to-5 metal can v os trim + C 6 t jmax = 175c, ja = 140c/w, jc = 40c/w obsolete package 1 2 3 4 5 6 7 8 top view Cin+in v C s8 package 8-lead plastic soic v + out + C v os trim v os trim over-comp t jmax = 150c, ja = 140c/w n8 package 8-lead plastic dip 1 2 3 4 5 6 7 8 top view Cin+in v C v+out + C over- comp v os trim v os trim t jmax = 150c, ja = 150c/w top view sw package 16-lead plastic sol 12 3 4 5 6 7 8 1615 14 13 12 11 10 9 ncnc trim Cin+in v C ncnc ncnc trim v + outnc nc over- comp + C t jmax = 150c, ja = 130c/w note: this device is not recommended for new designs j8 package 8-lead ceramic dip t jmax = 175c, ja = 140c/w, jc = 40c/w obsolete package pin configuration operating temperature range lt 1028 / lt 1128 am , m ( obsolete ) ... C55 c to 125 c lt 1028 / lt 1128 ac , c ( note 11) ............ C40 c to 85 c storage temperature range all devices ......................................... C65 c to 150 c lead temperature ( soldering , 10 sec .) .................. 300 c downloaded from: http:///
lt 1028/ lt 1128 3 1028fd for more information www.linear.com/lt1028 order information lead free finish tape and reel part marking* package description specified temperature range lt1028acn8#pbf n/a lt1028acn8 8-lead pdip 0c to 70c lt1028cn8#pbf n/a lt1028cn8 8-lead pdip 0c to 70c lt1128acn8#pbf n/a lt1128acn8 8-lead pdip 0c to 70c lt1128cn8#pbf n/a lt1128cn8 8-lead pdip 0c to 70c lt1028cs8#pbf lt1028cs8#trpbf 1028 8-lead plastic small outline 0c to 70c lt1128cs8#pbf lt1128cs8#trpbf 1128 8-lead plastic small outline 0c to 70c lt1028csw#pbf lt1028csw#trpbf lt1028csw 16-lead plastic soic (wide) 0c to 70c consult lt c marketing for parts specified with wider operating temperature ranges . * the temperature grade is identified by a label on the shipping container . for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ . some packages are available in 500 unit reels through designated sales channels with #trmpbf suffix. electrical characteristics v s = 15v, t a = 25c unless otherwise noted. lt1028am/ac lt1128am/ac lt1028m/c lt1128m/c symbol parameter conditions min typ max min typ max units v os input offset voltage (note 2) 10 40 20 80 v ?v os ?time long term input offset voltage stability (note 3) 0.3 0.3 v/mo i os input offset current v cm = 0v 12 50 18 100 na i b input bias current v cm = 0v 25 90 30 180 na e n input noise voltage 0.1hz to 10hz (note 4) 35 75 35 90 nv p-p input noise voltage density f o = 10hz (note 5) f o = 1000hz, 100% tested 1.00 0.85 1.7 1.1 1.0 0.9 1.9 1.2 nv/ hz nv/ hz i n input noise current density f o = 10hz (notes 4 and 6) f o = 1000hz, 100% tested 4.7 1.0 10.0 1.6 4.7 1.0 12.0 1.8 pa/ hz pa/ hz input resistance common mode differential mode 300 20 300 20 m k input capacitance 5 5 pf input voltage range 11.0 12.2 11.0 12.2 v cmrr common mode rejection ratio v cm = 11v 114 126 110 126 db psrr power supply rejection ratio v s = 4v to 18v 117 133 110 132 db a vol large-signal voltage gain r l 2k, v o = 12v r l 1k, v o = 10v r l 600, v o = 10v 7.0 5.0 3.0 30.0 20.0 15.0 5.0 3.5 2.0 30.0 20.0 15.0 v/v v/v v/v v out maximum output voltage swing r l 2k r l 600 12.3 11.0 13.0 12.2 12.0 10.5 13.0 12.2 v v sr slew rate a vcl = C1 lt1028 a vcl = C1 lt1128 11.0 5.0 15.0 6.0 11.0 4.5 15.0 6.0 v/s v/s gbw gain-bandwidth product f o = 20khz (note 7) lt1028 f o = 200khz (note 7) lt1128 50 13 75 20 50 11 75 20 mhz mhz z o open-loop output impedance v o = 0, i o = 0 80 80 i s supply current 7.4 9.5 7.6 10.5 ma downloaded from: http:///
lt 1028/ lt 1128 4 1028fd for more information www.linear.com/lt1028 electrical characteristics the l denotes the specifications which apply over the operating temperature range 0c t a 70c. v s = 15v, unless otherwise noted. lt1028ac lt1128ac lt1028c lt1128c symbol parameter conditions min typ max min typ max units v os input offset voltage (note 2) l 15 80 30 125 v ?v os ?temp average input offset drift (note 8) l 0.1 0.8 0.2 1.0 v/c i os input offset current v cm = 0v l 15 65 22 130 na i b input bias current v cm = 0v l 30 120 40 240 na input voltage range l 10.5 12.0 10.5 12.0 v cmrr common mode rejection ratio v cm = 10.5v l 110 124 106 124 db psrr power supply rejection ratio v s = 4.5v to 18v l 114 132 107 132 db a vol large-signal voltage gain r l 2k, v o = 10v r l 1k, v o = 10v l 5.0 4.0 25.0 18.0 3.0 2.5 25.0 18.0 v/v v/v v out maximum output voltage swing r l 2k r l 600 (note 10) l 11.5 9.5 12.7 11.0 11.5 9.0 12.7 10.5 v v i s supply current l 8.0 10.5 8.2 11.5 ma the l denotes the specifications which apply over the operating temperature range C55c t a 125c. v s = 15v, unless otherwise noted. lt1028am lt1128am lt1028m lt1128m symbol parameter conditions min typ max min typ max units v os input offset voltage (note 2) l 30 120 45 180 v ?v os ?temp average input offset drift (note 8) l 0.2 0.8 0.25 1.0 v/c i os input offset current v cm = 0v l 25 90 30 180 na i b input bias current v cm = 0v l 40 150 50 300 na input voltage range l 10.3 11.7 10.3 11.7 v cmrr common mode rejection ratio v cm = 10.3v l 106 122 100 120 db psrr power supply rejection ratio v s = 4.5v to 16v l 110 130 104 130 db a vol large-signal voltage gain r l 2k, v o = 10v r l 1k, v o = 10v l 3.0 2.0 14.0 10.0 2.0 1.5 14.0 10.0 v/v v/v v out maximum output voltage swing r l 2k l 10.3 11.6 10.3 11.6 v i s supply current l 8.7 11.5 9.0 13.0 ma downloaded from: http:///
lt 1028/ lt 1128 5 1028fd for more information www.linear.com/lt1028 lt1028ac lt1128ac lt1028c lt1128c symbol parameter conditions min typ max min typ max units v os input offset voltage l 20 95 35 150 v ?v os ?temp average input offset drift (note 8) l 0.2 0.8 0.25 1.0 v/c i os input offset current v cm = 0v l 20 80 28 160 na i b input bias current v cm = 0v l 35 140 45 280 na input voltage range l 10.4 11.8 10.4 11.8 v cmrr common mode rejection ratio v cm = 10.5v l 108 123 102 123 db psrr power supply rejection ratio v s = 4.5v to 18v l 112 131 106 131 db a vol large-signal voltage gain r l 2k, v o = 10v r l 1k, v o = 10v l 4.0 3.0 20.0 14.0 2.5 2.0 20.0 14.0 v/v v/v v out maximum output voltage swing r l 2k l 11.0 12.5 11.0 12.5 v i s supply current l 8.5 11.0 8.7 12.5 ma the l denotes the specifications which apply over the operating temperature range C40c t a 85c. v s = 15v, unless otherwise noted. (note 11) note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2: input offset voltage measurements are performed by automatic test equipment approximately 0.5 sec. after application of power. in addition, at t a = 25c, offset voltage is measured with the chip heated to approximately 55c to account for the chip temperature rise when the device is fully warmed up.note 3: long term input offset voltage stability refers to the average trend line of offset voltage vs time over extended periods after the first 30 days of operation. excluding the initial hour of operation, changes in v os during the first 30 days are typically 2.5v.note 4: this parameter is tested on a sample basis only. note 5: 10hz noise voltage density is sample tested on every lot with the exception of the s8 and s16 packages. devices 100% tested at 10hz are available on request. note 6: current noise is defined and measured with balanced source resistors. the resultant voltage noise (after subtracting the resistor noise on an rms basis) is divided by the sum of the two source resistors to obtain current noise. maximum 10hz current noise can be inferred from 100% testing at 1khz. note 7: gain-bandwidth product is not tested. it is guaranteed by design and by inference from the slew rate measurement.note 8: this parameter is not 100% tested. note 9: the inputs are protected by back-to-back diodes. current-limiting resistors are not used in order to achieve low noise. if differential input voltage exceeds 1.8v, the input current should be limited to 25ma.note 10: this parameter guaranteed by design, fully warmed up at t a = 70c. it includes chip temperature increase due to supply and load currents. note 11: the lt1028/lt1128 are designed, characterized and expected to meet these extended temperature limits, but are not tested at C40c and 85c. guaranteed i-grade parts are available. consult factory. electrical characteristics downloaded from: http:///
lt 1028/ lt 1128 6 1028fd for more information www.linear.com/lt1028 typical performance characteristics 10hz voltage noise distribution total noise vs matched source resistance total noise vs unmatched source resistance current noise spectrum 0.01hz to 1hz voltage noise voltage noise vs temperature 0.1hz to 10hz voltage noise wideband noise, dc to 20khz wideband voltage noise (0.1hz to frequency indicated) 0.6 0 number of units 20 60 80 100 1.0 1.4 1.8 180 1028 g01 40 0.8 1.2 120 140 160 1.6 2.0 2.2 8 70 148 158 57 28 7 4 2 3 2 2 2 1 3 2 1 1 1 v s = 15v t a = 25c 500 unitsmeasured from 4 runs voltage noise density (nv/ hz ) 1028 g02 vertical scale = 0.5v/div horizontal scale = 0.5ms/div bandwidth (hz) 100 rms voltage noise (v) 0.1 1 100k 1m 10m 1028 g03 0.01 10 10k 1k v s = 15v t a = 25c matched source resistance () 1 total noise density (nv/ hz ) 10 100 3 1k 10k 1028 g04 1 0.1 v s = 15v t a = 25c 10 30 100 300 3k at 10hz 2 r s noise only at 1khz ? + r s r s unmatched source resistance () 1 total noise density (nv/ hz ) 10 100 3 1k 10k 1028 g05 1 0.1 v s = 15v t a = 25c 10 30 100 300 3k at 10hz 2 r s noise only at 1khz r s frequency (hz) 10 0.1 current noise density (pa/ hz ) 1 10 100 100 1k 10k 1028 g06 maximum typical 1/f corner = 800hz 1/f corner = 250hz time (sec) 0 8 1028 g07 2 4 6 10 10nv v s = 15v t a = 25c time (sec) 0 80 1028 g08 20 40 60 100 10nv v s = 15v t a = 25c temperature (c) C50 0 rms voltage density (nv/ hz ) 0.8 2.0 0 50 75 1028 g09 o.4 1.6 1.2 C25 25 100 125 v s = 15v at 10hz at 1khz downloaded from: http:///
lt 1028/ lt 1128 7 1028fd for more information www.linear.com/lt1028 typical performance characteristics supply current vs temperature voltage noise vs supply voltage bias current over the common mode range warm-up drift output short-circuit current vs time distribution of input offset voltage input bias and offset currents over temperature long-term stability of five representative units offset voltage drift with temperature of representative units offset voltage (v) C50 units (%) 12 16 20 30 1028 g10 8 4 0 C30 C10 10 50 10 14 18 6 2 20 C40 C20 0 40 v s = 15v t a = 25c 800 units testedfrom four runs temperature (c) C50 C50 offset voltage (v) C40 C20 C10 0 50 20 0 50 75 1028 g11 C30 30 40 10 C25 25 100 125 v s = 15v time (months) 0 offset voltage change (v) 2 6 10 4 1028 g12 C2 C6 C10 1 2 3 5 0 4 8 C4 C8 v s = 15v t a = 25c t = 0 after 1 day pre-warm up time after power on (minutes) 0 0 change in offset voltage (v) 4 8 12 16 20 24 1 2 3 4 1028 g13 5 v s = 15v t a = 25c metal can (h) package dual-in-line packageplastic (n) or cerdip (j) temperature (c) C50 input bias and offset currents (na) 40 50 60 25 75 1028 g14 30 20 C25 0 50 100 125 10 0 v s = 15v v cm = 0v bias current offset current common mode input voltage (v) C15 C80 input bias current (na) C60 C20 0 20 C5 5 15 100 1028 g15 C40 C10 0 40 60 80 10 r cm = 20v 65na a 300m v s = 15v t a = 25c positive input current (undercancelled) device negative input current(overcancelled) device temperature (c) C50 0 supply current (ma) 1 3 4 5 10 7 0 50 75 1028 g17 2 8 9 6 C25 25 100 125 v s = 15v v s = 5v time from output short to ground (minutes) 0 C50 sinking C40 C20 C10 0 50 20 2 1028 g18 C30 30 40 10 1 3 short-circuit current (ma) sourcing v s = 15v C50c 25c 125c C50c 125c 25c supply voltage (v) 0 rms voltage noise density (nv/ hz ) 1.0 1.25 15 1028 g16 0.75 0.5 5 10 20 1.5 t a = 25c at 10hzat 1khz downloaded from: http:///
lt 1028/ lt 1128 8 1028fd for more information www.linear.com/lt1028 typical performance characteristics gain error vs frequencyclosed-loop gain = 1000 lt1128gain phase vs frequency lt1028gain, phase vs frequency voltage gain vs frequency voltage gain vs supply voltage voltage gain vs load resistance maximum undistorted outputvs frequency lt1128capacitance load handling lt1028capacitance load handling frequency (hz) 0.01 C20 voltage gain (db) 160 1028 g19 140120 100 8060 40 20 0 0.1 1 10 100 1k 10k 100k 1m 10m 100m lt1128 lt1028 v s = 15v t a = 25c r l = 2k frequency (hz) 10 voltage gain (db) 20 40 50 70 10k 1m 10m 100m 1028 g20 ?10 100k 6030 0 v s = 15v t a = 25c c l = 10pf gain phase 10 20 40 50 70 ?10 6030 0 phase margin (deg) capacitive load (pf) 10 40 overshoot (%) 50 60 70 80 100 1000 10000 1028 g21 3020 10 0 v s = 15v t a = 25c C + c l 2k 30pf r s a v = C1, r s = 2k a v = C100 r s = 20 a v = C10 r s = 200 frequency (hz) 0.1 0.001 gain error (%) 0.01 0.1 1 1 100 1028 g22 lt1128 lt1028 typical precision op amp gain error = closed-loop gain open-loop gain 10 frequency (hz) 10 voltage gain (db) 20 40 50 70 10k 1m 10m 100m 1028 g23 C10 100k 6030 0 v s = 15v t a = 25c c l = 10pf gain phase 10 20 40 50 70 C10 6030 0 phase margin (deg) capacitive load (pf) 10 40 overshoot (%) 50 60 70 80 100 1000 10000 1028 g24 3020 10 0 v s = 15v t a = 25c v o = 10mv p-p a v = C1, r s = 2k C + c l 2k 30pf r s a v = C10 r s = 200 a v = ?100, r s = 20 supply voltage (v) 5 1 10 100 10 15 1028 g25 voltage gain (v/v) 0 2 0 t a = 25c r l = 2k r l = 600 load resistance (k) 0.1 1 voltage gain (v/v) 10 100 1 10 1028 g26 v s = 15v t a = C55c t a = 25c t a = 125c i lmax = 35ma at C55c = 27ma at 25c= 16ma at 125c frequency (hz) 10k 5 peak-to-peak output voltage (v) 20 25 30 100k 1m 10m 1028 g27 1510 lt1128 lt1028 v s = 15v t a = 25c r l = 2k downloaded from: http:///
lt 1028/ lt 1128 9 1028fd for more information www.linear.com/lt1028 typical performance characteristics lt1128 large-signal transient response lt1028slew rate, gain-bandwidth product over temperature lt1128 slew rate, gain-bandwidth product over temperature lt1028 slew rate, gain-bandwidth product vs over-compensation capacitor lt1128slew rate, gain-bandwidth product vs over-compensation capacitor closed-loop output impedance lt1128 small-signal transient response lt1028 large-signal transient response lt1028 small-signal transient response 1028 g28 1s/div 5v/div 10v C10v a v = C1, r s = r f = 2k, c f = 15pf 1028 g29 0.2s/div 20mv/div 50mv C50mv a v = C1, r s = r f = 2k, c f = 15pf, c l = 80pf temperature (c) C50 slew rate (v/s) 16 17 18 25 75 1028 g30 15 14 C25 0 50 100 125 13 12 v s = 15v 70 80 90 60 50 40 30 gain-bandwidth product (f o = 20khz), (mhz) gbw fall rise 1028 g31 2s/div 0v 10v C10v a v = C1, r s = r f = 2k, c f = 30pf 1028 g32 0.2s/div 0v 50mv C50mv a v = C1, c l = 10pf temperature (c) C50 0 slew rate (v/s) 1 3 4 5 0 50 100 9 1028 g33 2 C25 25 6 7 8 75 125 2010 30 gain-bandwidth product (f o = 200khz), (mhz) fall rise gbw frequency (hz) 10 output impedance () 1 10 100 100k 1028 g34 0.1 0.01 0.001 100 1k 10k 1m i o = 1ma v s = 15v t a = 25c lt1128 lt1028 lt1128 lt1028 a v = 1000 a v = 5 over-compensation capacitor (pf) 1 slew rate (v/s) 10 1 100 1000 10000 0.1 10 100 10 1001 1k gain at 200khz gbw slew rate over-compensation capacitor (pf) 1 10 1 100 1000 10000 1028 g35 0.1 10 100 10 100 1k gbw slew rate 1 over-compensation capacitor (pf) 1 slew rate (v/s) 10 1 100 1000 10000 1028 g36 0.1 10 100 1k 10k gain at 20khz c oc from pin 5 to pin 6 v s = 15v t a = 25c slew gbw 10010 downloaded from: http:///
lt 1028/ lt 1128 10 1028fd for more information www.linear.com/lt1028 typical performance characteristics lt1128 total harmonic distortion vs closed-loop gain common mode limit over temperature lt1028 total harmonic distortion vs frequency and load resistance common mode rejection ratiovs frequency power supply rejection ratiovs frequency high frequency voltage noise vs frequency lt1028 total harmonic distortion vs closed-loop gain lt1128 total harmonic distortion vs frequency and load resistance temperature (c) C50 v C common mode limit (v) referred to power supply 1 3 4 v + C3 0 50 75 1028 g37 2 C2 C1 C4 C25 25 100 125 v s = 5v v s = 5v to 15v v s = 15v frequency (hz) 10 80 100 120 10k 1m 1028 g38 6040 100 1k 100k 10m 20 0 common mode rejection ratio (db) 140 v s = 15v t a = 25c lt1128 lt1028 frequency (hz) 0.1 power supply rejection ratio (db) 80 100 120 10m 1028 g39 60 40 0 10 1k 100k 20 160 140 1m 1 100 10k v s = 15v t a = 25c negative supply positive supply frequency (khz) 1 0.001 total harmonic distortion (%) 0.01 0.1 10 100 1028 g40 a v = 1000 r l = 600 a v = 1000 r l = 2k v o = 20v p-p v s = 15v t a = 25c a v = C1000 r l = 2k a v = 1000 r l = 600 closed loop gain 0.001 total harmonic distortion (%) 0.01 10 1k 10k 100k 1028 g41 0.0001 100 0.1 v o = 20v p-p f = 1khzv s = 15v t a = 25c r l = 10k non-inverting gain invertinggain measuredextrapolated frequency (hz) 10k 0.1 1.0 10 100k 1m 1028 g42 noise voltage density (nv/ hz ) frequency (khz) 1.0 0.001 total harmonic distortion (%) 0.1 1.0 10 100 1028 g43 0.01 a v = 1000 r l = 600 a v = ?1000 r l = 2k v o = 20v p-p v s = 15v t a = 25c a v = 1000 r l = 609 a v = 1000 r l = 2k closed loop gain 0.001 total harmonic distortion (%) 0.01 10 1k 10k 100k 1028 g44 0.0001 100 0.1 v o = 20v p-p f = 1khzv s = 15v t a = 25c r l = 10k non-inverting gain invertinggain measuredextrapolated downloaded from: http:///
lt 1028/ lt 1128 11 1028fd for more information www.linear.com/lt1028 applications information ? noise voltage noise vs current noise the lt1028/lt1128s less than 1 nv/ hz voltage noise is three times better than the lowest voltage noise heretofore available ( on the lt1007/1037). a necessary condition for such low voltage noise is operating the input transistors at nearly 1 ma of collector currents, because voltage noise is inversely proportional to the square root of the collector current. current noise, however, is directly proportional to the square root of the collector current. consequently, the lt1028/lt1128s current noise is significantly higher than on most monolithic op amps. therefore, to realize truly low noise performance it is important to understand the interaction between voltage noise (e n ), current noise (i n ) and resistor noise (r n ). total noise vs source resistance the total input referred noise of an op amp is given by: e t = [e n 2 + r n 2 + (i n r eq ) 2 ] 1/2 where r eq is the total equivalent source resistance at the two inputs, and r n = 4ktr eq = 0.13 req in nv/ hz at 25c as a numerical example, consider the total noise at 1 khz of the gain 1000 amplifier shown in figure 1. the largest term, as in the example above, and the lt1028/ lt1128s voltage noise becomes negligible. as r eq is further increased, current noise becomes important. at 1khz, when r eq is in excess of 20 k, the current noise component is larger than the resistor noise. the total noise versus matched source resistance plot illustrates the above calculations. the plot also shows that current noise is more dominant at low frequencies, such as 10 hz. this is because resistor noise is flat with frequency, while the 1/ f corner of current noise is typically at 250 hz. at 10 hz when r eq > 1 k, the current noise term will exceed the resistor noise. when the source resistance is unmatched, the total noise versus unmatched source resistance plot should be con - sulted. note that total noise is lower at source resistances below 1 k because the resistor noise contribution is less. when r s > 1 k total noise is not improved, however. this is because bias current cancellation is used to reduce input bias current. the cancellation circuitry injects two correlated current noise components into the two inputs. with matched source resistors the injected current noise creates a common-mode voltage noise and gets rejected by the amplifier. with source resistance in one input only, the cancellation noise is added to the amplifiers inherent noise. in summary, the lt1028/lt1128 are the optimum am - plifiers for noise performance, provided that the source resistance is kept low. the following table depicts which op amp manufactured by linear technology should be used to minimize noise, as the source resistance is increased beyond the lt1028/lt1128s level of usefulness. table 1. best op amp for lowest total noise vs source resistance source resis- tance () (note 1) best op amp at low freq (10hz) wideband (1khz) 0 to 400 lt1028/lt1128 lt1028/lt1128 400 to 4k lt1007/1037 lt1028/lt1128 4k to 40k lt1001 lt1007/lt1037 40k to 500k lt1012 lt1001 500k to 5m lt1012 or lt1055 lt1012 >5m lt1055 lt1055 note 1: source resistance is defined as matched or unmatched, e.g., r s = 1k means: 1k at each input, or 1k at one input and zero at the other. r eq = 100 + 100 || 100k 200 r n = 0.13 200 = 1.84nv hz e n = 0.85nv hz i n = 1.0pa/ hz e t = [0.85 2 + 1.84 2 + (1.0 0.2) 2 ] 1/2 = 2.04nv/ hz output noise = 1000 e t = 2.04v/ hz at very low source resistance ( r eq < 40) voltage noise dominates. as r eq is increased resistor noise becomes C + 100 100k 100 lt1028lt1128 1028 f01 figure 1 downloaded from: http:///
lt 1028/ lt 1128 12 1028fd for more information www.linear.com/lt1028 applications information ? noise noise testing C voltage noise the lt1028/lt1128s rms voltage noise density can be accurately measured using the quan tech noise analyzer, model 5173 or an equivalent noise tester. care should be taken, however, to subtract the noise of the source resistor used. prefabricated test cards for the model 5173 set the device under test in a closed-loop gain of 31 with a 60 source resistor and a 1.8 k feedback resistor. the noise of this resistor combination is 0.13 58 = 1.0 nv/ hz . an lt1028/lt1128 with 0.85 nv/ hz noise will read (0.85 2 + 1.0 2 ) 1/2 = 1.31 nv/ hz . for better resolution, the resistors should be replaced with a 10 source and 300 feedback resistor. even a 10 resistor will show an apparent noise which is 8% to 10% too high.the 0.1 hz to 10 hz peak-to-peak noise of the lt1028/ lt1128 is measured in the test circuit shown. the fre - quency response of this noise tester indicates that the 0.1hz corner is defined by only one zero. the test time to measure 0.1 hz to 10 hz noise should not exceed 10 seconds, as this time limit acts as an additional zero to eliminate noise contributions from the frequency band below 0.1hz. measuring the typical 35 nv peak - to - peak noise per - formance of the lt1028/lt1128 requires special test precautions: (a) the device should be warmed up for at least five minutes. as the op amp warms up, its offset voltage changes typically 10 v due to its chip temperature increasing 30 c to 40 c from the moment the power supplies are turned on. in the 10 second measurement interval these temperature-induced effects can easily exceed tens of nanovolts. (b) for similar reasons, the device must be well shielded from air current to eliminate the possibility of ther - moelectric effects in excess of a few nanovolts, which would invalidate the measurements. (c) sudden motion in the vicinity of the device can also feedthrough to increase the observed noise. a noise - voltage density test is recommended when measur - ing noise on a large number of units. a 10 hz noise-voltage density measurement will correlate well with a 0.1 hz to 10hz peak-to-peak noise reading since both results are determined by the white noise and the location of the 1/ f corner frequency. figure 2. 0.1hz to 10hz noise test circuit figure 3. 0.1hz to 10hz peak-to-peak noise tester frequency response C + voltage gain = 50,000* device under test note all capacitor values are for nonpolarized capacitors only 100k 10 C + 2k 4.7f 0.1f 100k 24.3k 22f 2.2f 4.3k 110k scope 1 r in = 1m 0.1f * 1028 f02 lt1001 frequency (hz) 40 gain (db) 60 70 90 100 0.01 1.0 10 100 1028 f03 30 0.1 50 80 downloaded from: http:///
lt 1028/ lt 1128 13 1028fd for more information www.linear.com/lt1028 applications information ? noise noise testing C current noise current noise density ( i n ) is defined by the following for- mula, and can be measured in the circuit shown in figure 4. l n = e no 2 ? 31? 18.4nv/ hz ( ) 2 ?? ? ?? ? 20k ? 31 1/2 if the quan tech model 5173 is used, the noise reading is input-referred, therefore the result should not be divided by 31; the resistor noise should not be multiplied by 31. 100% noise testing the 1 khz voltage and current noise is 100% tested on the lt1028/lt1128 as part of automated testing; the approximate frequency response of the filters is shown. the limits on the automated testing are established by extensive correlation tests on units measured with the quan tech model 5173. 10hz voltage noise density is sample tested on every lot. devices 100% tested at 10 hz are available on request for an additional charge. 10hz current noise is not tested on every lot but it can be inferred from 100% testing at 1 khz. a look at the current noise spectrum plot will substantiate this statement. the only way 10 hz current noise can exceed the guaranteed limits is if its 1/ f corner is higher than 800 hz and/or its white noise is high. if that is the case then the 1 khz test will fail. figure 5. automated tester noise filter C + e no 1.8k 60 lt1028lt1128 10k 10k 1028 f04 frequency (hz) 100 C50 noise filter loss (db) C10 0 10 1k 10k 100k 1028 f05 C20 C40 C30 current noise voltagenoise figure 4 downloaded from: http:///
lt 1028/ lt 1128 14 1028fd for more information www.linear.com/lt1028 figure 7. test circuit for offset voltage and offset voltage drift with temperature C + r f 1028 f08 output 6v/s C + C15v 10k* 200* lt1028lt1128 1028 f07 10k* v o = 100v os * resistors must have low thermoelectric potential v o 6 7 2 4 3 15v applications information generalthe lt1028 / lt1128 series devices may be inserted directly into op-07, op-27, op-37, lt1007 and lt1037 sockets with or without removal of external nulling components. in addition, the lt1028 / lt1128 may be fitted to 5534 sockets with the removal of external compensation components. offset voltage adjustment the input offset voltage of the lt1028/lt1128 and its drift with temperature, are permanently trimmed at wafer test - ing to a low level. however, if further adjustment of v os is necessary, the use of a 1 k nulling potentiometer will not degrade drift with temperature. trimming to a value other than zero creates a drift of ( v os /300)v/c, e.g., if v os is adjusted to 300v, the change in drift will be 1v/c. the adjustment range with a 1 k pot is approximately 1.1mv. unity-gain buffer applications (lt1128 only) when r f 100 and the input is driven with a fast, large- signal pulse (>1 v ), the output waveform will look as shown in the pulsed operation diagram (figure 8). C + 6 1k input lt1028lt1128 1028 f06 7 8 1 2 3 4 output C15v 15v figure 6 figure 8 offset voltage and drift thermocouple effects, caused by temperature gradients across dissimilar metals at the contacts to the input termi - nals, can exceed the inherent drift of the amplifier unless proper care is exercised. air currents should be minimized , package leads should be short, the two input leads should be close together and maintained at the same temperature . the circuit shown in figure 7 to measure offset voltage is also used as the burn-in configuration for the lt1028/ lt1128. during the fast feedthrough-like portion of the output, the input protection diodes effectively short the output to the input and a current, limited only by the output short-circuit protection, will be drawn by the signal generator. with r f 500, the output is capable of handling the current requirements (i l 20ma at 10v) and the amplifier stays in its active mode and a smooth transition will occur. as with all operational amplifiers when r f > 2 k, a pole will be created with rf and the amplifiers input capacitance, creating additional phase shift and reducing the phase margin. a small capacitor (20pf to 50pf) in parallel with r f will eliminate this problem. downloaded from: http:///
lt 1028/ lt 1128 15 1028fd for more information www.linear.com/lt1028 applications information frequency response the lt1028s gain, phase vs frequency plot indicates that the device is stable in closed-loop gains greater than +2 or C1 because phase margin is about 50 at an open - loop gain of 6 db. in the voltage follower configuration phase margin seems inadequate. this is indeed true when the output is shorted to the inverting input and the noninverting input is driven from a 50 source impedance. however, when feedback is through a parallel r-c network ( provided c f < 68 pf), the lt1028 will be stable because of interaction between the input resistance and capacitance and the feedback network. larger source resistance at the non - inverting input has a similar effect. the following voltage follower configurations are stable: another configuration which requires unity-gain stability is shown below. when c f is large enough to effectively short the output to the input at 15 mhz, oscillations can occur. the insertion of r s2 500 will prevent the lt1028 from oscillating. when r s1 500, the additional noise contribution due to the presence of r s2 will be minimal. when r s1 100, r s2 is not necessary, because r s1 represents a heavy load on the output through the c f short . when 100 < r s1 < 500, r s2 should match r s1 . for example, r s1 = r s2 = 300 will be stable. the noise increase due to r s2 is 40%. if c f is only used to cut noise bandwidth, a similar effect can be achieved using the over-compensation terminal. the gain, phase plot also shows that phase margin is about 45 at gain of 10 (20 db). the following configuration has a high (70%) overshoot without the 10 pf capacitor because of additional phase shift caused by the feedback resistor C input capacitance pole. the presence of the 10 pf capacitor cancels this pole and reduces overshoot to 5%. 1028 f09 C + 33pf 2k lt1028 50 C + lt1028 50 500 1028 f10 c1 r1 r s1 r s2 lt1028 C + 1028 f11 10pf 10k 50 1.1k ? + lt1028 figure 9 over-compensation the lt1028/lt1128 are equipped with a frequency over- compensation terminal ( pin 5). a capacitor connected between pin 5 and the output will reduce noise bandwidth. details are shown on the slew rate, gain-bandwidth prod - uct vs over-compensation capacitor plot. an additional benefit is increased capacitive load handling capability. figure 10figure 11 downloaded from: http:///
lt 1028/ lt 1128 16 1028fd for more information www.linear.com/lt1028 low noise voltage regulator 1028 ta04 10f 2k 20v output C + lt1028 121 provides pre-reg and currentlimiting 10f + 28v 2.32k 2k 330 1000pf 1k 28v lt317a out adj in lt1021-10 2n6387 typical applications strain gauge signal conditioner with bridge excitation 1028 ta03 1f referenceoutput C + lt1128 30.1k* 49.9* 15v 330 10kzero trim 5.0v 301k* lt1021-5 0v to 10v output 3 2 7 6 4 350 bridge ?15v 15v 15v lt1028 ? + 3 2 7 6 4 ?15v lt1028 ? + 3 2 7 6 4 ?15v 5kgain trim 330 *rn60c film resistors the lt1028?s noise contribution is negligiblecompared to the bridge noise. downloaded from: http:///
lt 1028/ lt 1128 17 1028fd for more information www.linear.com/lt1028 typical applications paralleling amplifiers to reduce voltage noise 1028 ta05 C + 1.5k a1 lt1028 470 output ? + 7.5 4.7k ? + 1.5k 470 7.5 ? + 1.5k 470 7.5 a2 lt1028 an lt1028 lt1028 output noise n ? 200 2v 5 1. assume voltage noise of lt1028 and 7.5 source resistor = 0.9nv/ hz . 2. gain with n lt1028s in parallel = n ? 200.3. output noise = n ? 200 ? 0.9nv/ hz . 4. input referred noise = = nv/ hz . 5. noise current at input increases n times. 6. if n = 5, gain = 1000, bandwidth = 1mhz, rms noise, dc to 1mhz = = 0.9v. 0.9 n downloaded from: http:///
lt 1028/ lt 1128 18 1028fd for more information www.linear.com/lt1028 tape head amplifier phono preamplifier typical applications 1028 ta06 0.1f 10 ?15v 10k ? + lt1028 output 787 0.33f 100pf 47k mag phono input 4 6 7 15v 23 all resistors metal film 1028 ta07 0.1f 10 ? + lt1028 output 499 tape head input 6 31.6k 23 all resistors metal film downloaded from: http:///
lt 1028/ lt 1128 19 1028fd for more information www.linear.com/lt1028 low noise, wide bandwidth instrumentation amplifier gyro pick-off amplifier typical applications 1028 ta08 10 ? + lt1028 output 820 +input 68pf 10k 50 68pf 820 ? + lt1028 ?input ? + lt1028 300 300 10k gain = 1000, bandwidth = 1mhzinput referred noise = 1.5nv/ hz at 1khz wideband noise Cdc to 1mhz = 3v rms if bw limited to dc to 100khz = 0.55v rms 1028 ta09 100 output to sync demodulator 1k ? + lt1028 sine drive ? gyro typical? northrop corp. gr-f5ah7-5b downloaded from: http:///
lt 1028/ lt 1128 20 1028fd for more information www.linear.com/lt1028 1028 ta10 C + lt1028 c2 0.047 r2 r1 c1 0.047 2k 20 20 2k 10pf 5.6k 15f + 22k 10k ? + lt1055 1v rms output 1.5khz to 15khzwhere r1c1 = r2c2 f = 1 2rc ( ) mount 1n4148sin close proximity trim for lowest distortion 100k 10k 20k 2n4338 560 2.4k 4.7k lt1004-1.2v 15v <0.0018% distortion and noise. measurement limited by resolution of hp339a distortion analyzer 1028 ta11 ? + lt1052 10 0.1 30k 10k 15v 7 6 4 2 3 8 1 ?15v 0.1 0.01 15v 68 ? + lt1028 130 1 7 8 4 ?15v input output 1n758 1n758 100k 2 3 typical applications super low distortion variable sine wave oscillator chopper-stabilized amplifier downloaded from: http:///
lt 1028/ lt 1128 21 1028fd for more information www.linear.com/lt1028 schematic diagram 1.5a 1 null r5130 r6130 r13k r23k 3 8 null q4 c1257pf 900a 900a q6 q5 q9 q8 q7 q2 4.5a 4.5a 1.5a q13 q14 q1 4.5a non- inverting input 0 1.8ma q3 bias 2 inverting input 4 v C r780 q11 q10 q12 300a q15 q21 5 over-comp q23 600a r12 240 c4 35pf q22 r11 100 c3 250pf q19 q18 q16 q17 r11400 r10400 1.1ma 2.3ma 400a v + 7 r10 500 c2 q26 q25 q24 6 output q27 1028 ta12 4.5a 3 1 3 1 q20 r8480 500a c2 = 50pf for lt1028 c2 = 275pf for lt1128 downloaded from: http:///
lt 1028/ lt 1128 22 1028fd for more information www.linear.com/lt1028 package description please refer to http:// www .linear.com/product/lt1028#packaging for the most recent package drawings. obsolete package j8 0801 .014 ? .026 (0.360 ? 0.660) .200 (5.080) max .015 ? .060 (0.381 ? 1.524) .125 3.175 min .100 (2.54) bsc .300 bsc (7.62 bsc) .008 ? .018 (0.203 ? 0.457) 0 ? 15 .005 (0.127) min .405 (10.287) max .220 ? .310 (5.588 ? 7.874) 1 2 3 4 8 7 6 5 .025 (0.635) rad typ .045 ? .068 (1.143 ? 1.650) full lead option .023 ? .045 (0.584 ? 1.143) half lead option corner leads option (4 plcs) .045 ? .065 (1.143 ? 1.651) note: lead dimensions apply to solder dip/plate or tin plate leads j8 package 3-lead cerdip (narrow .300 inch, hermetic) (reference ltc dwg # 05-08-1110) downloaded from: http:///
lt 1028/ lt 1128 23 1028fd for more information www.linear.com/lt1028 package description please refer to http:// www .linear.com/product/lt1028#packaging for the most recent package drawings. n8 rev i 0711 .065 (1.651) typ .045 ? .065 (1.143 ? 1.651) .130 .005 (3.302 0.127) .020 (0.508) min .018 .003 (0.457 0.076) .120 (3.048) min .008 ? .015 (0.203 ? 0.381) .300 ? .325 (7.620 ? 8.255) .325 +.035?.015 +0.889?0.381 8.255 ( ) 1 2 3 4 8 7 6 5 .255 .015* (6.477 0.381) .400* (10.160) max note:1. dimensions are inches millimeters *these dimensions do not include mold flash or protrusions. mold flash or protrusions shall not exceed .010 inch (0.254mm) .100 (2.54) bsc n package 8-lead pdip (narrow .300 inch) (reference ltc dwg # 05-08-1510 rev i) downloaded from: http:///
lt 1028/ lt 1128 24 1028fd for more information www.linear.com/lt1028 package description please refer to http:// www .linear.com/product/lt1028#packaging for the most recent package drawings. .016 ? .050 (0.406 ? 1.270) .010 ? .020 (0.254 ? 0.508) 45 0 ? 8 typ .008 ? .010 (0.203 ? 0.254) so8 rev g 0212 .053 ? .069 (1.346 ? 1.752) .014 ? .019 (0.355 ? 0.483) typ .004 ? .010 (0.101 ? 0.254) .050 (1.270) bsc 1 2 3 4 .150 ? .157 (3.810 ? 3.988) note 3 8 7 6 5 .189 ? .197 (4.801 ? 5.004) note 3 .228 ? .244 (5.791 ? 6.197) .245 min .160 .005 recommended solder pad layout .045 .005 .050 bsc .030 .005 typ inches (millimeters) note:1. dimensions in 2. drawing not to scale 3. these dimensions do not include mold flash or protrusions. mold flash or protrusions shall not exceed .006" (0.15mm) 4. pin 1 can be bevel edge or a dimple s8 package 8-lead plastic small outline (narrow .150 inch) (reference ltc dwg # 05-08-1610 rev g) downloaded from: http:///
lt 1028/ lt 1128 25 1028fd for more information www.linear.com/lt1028 package description please refer to http:// www .linear.com/product/lt1028#packaging for the most recent package drawings. .016 ? .050 (0.406 ? 1.270) .010 ? .020 (0.254 ? 0.508) 45 0 ? 8 typ .008 ? .010 (0.203 ? 0.254) 1 n 2 3 4 5 6 7 8 n/2 .150 ? .157 (3.810 ? 3.988) note 3 16 15 14 13 .386 ? .394 (9.804 ? 10.008) note 3 .228 ? .244 (5.791 ? 6.197) 12 11 10 9 s16 rev g 0212 .053 ? .069 (1.346 ? 1.752) .014 ? .019 (0.355 ? 0.483) typ .004 ? .010 (0.101 ? 0.254) .050 (1.270) bsc .245 min n 1 2 3 n/2 .160 .005 recommended solder pad layout .045 .005 .050 bsc .030 .005 typ inches (millimeters) note:1. dimensions in 2. drawing not to scale3. these dimensions do not include mold flash or protrusions. mold flash or protrusions shall not exceed .006" (0.15mm) 4. pin 1 can be bevel edge or a dimple s package 16-lead plastic small outline (narrow .150 inch) (reference ltc dwg # 05-08-1610 rev g) downloaded from: http:///
lt 1028/ lt 1128 26 1028fd for more information www.linear.com/lt1028 package description obsolete package please refer to http:// www .linear.com/product/lt1028#packaging for the most recent package drawings. .050 (1.270) max .016 ? .021** (0.406 ? 0.533) .010 ? .045* (0.254 ? 1.143) seating plane .040 (1.016) max .165 ? .185 (4.191 ? 4.699) gaugeplane reference plane .500 ? .750 (12.700 ? 19.050) .305 ? .335 (7.747 ? 8.509) .335 ? .370 (8.509 ? 9.398) dia .230 (5.842) typ .027 ? .045 (0.686 ? 1.143) .028 ? .034 (0.711 ? 0.864) .110 ? .160 (2.794 ? 4.064) insulating standoff 45 h8 (to-5) 0.230 pcd 0204 lead diameter is uncontrolled between the reference plane and the seating plane for solder dip lead finish, lead diameter is .016 ? .024 (0.406 ? 0.610) * ** pin 1 h package 8-lead to-5 metal can (.230 inch pcd) (reference ltc dwg # 05-08-1321) downloaded from: http:///
lt 1028/ lt 1128 27 1028fd for more information www.linear.com/lt1028 information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. revision history rev date description page number b 10/12 replaced the typical application. 1 c 10/14 corrected diagram to show n8 package is not obsolete. changed t jmax to 150c for s8 and sw packages. corrected right-hand electrical characteristics column to reflect non-a-grade specs.corrected lm301a and lt1012 input polarity. 22 3 28 d 10/15 corrected component values in low noise voltage regulator circuit. 16 (revision history begins at rev b) downloaded from: http:///
lt 1028/ lt 1128 28 1028fd for more information www.linear.com/lt1028 ? linear technology corporation 1992 lt 1015 rev d ? printed in usa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com/lt1028 related parts typical application part number description comments lt1806/lt1807 325mhz, 3.5nv / hz single and dual op amps slew rate = 140v/s, low distortion at 5mhz: C80dbc low noise infrared detector 1028 ta13 10 1m 1k 10k 5v ? + lt1028 7 6 4 2 3 8 ?5v 1000f dc out 5v 39 33 + 267 10 + + optical chopper wheel ir radiation photo- electric pick-off infra red associates, inc.hgcdte ir detector 13 at 77k 1/4 ltc1043 30pf 100f 100f 13 14 16 10k* 10k* synchronousdemodulator + ? lt1012 7 4 2 3 ?5v 6 5v 1 8 12 + ? lm301a 7 4 2 3 ?5v 6 5v 1 8 downloaded from: http:///

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