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rev. b information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. no license is granted by implication or otherwise under any patent or patent rights of analog devices. a OP37 one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781/329-4700 www.analog.com fax: 781/326-8703 ? analog devices, inc., 2002 low noise, precision, high speed operational amplifier (a vcl > 5) simplified schematic v? v+ q2b r2 * q3 q2a q1a q1b r4 r1 * r3 18 v os adj. r1 and r2 are permanently adjusted at wafer test for minimum offset voltage. * non-inverting input (+) inverting input (?) q6 q21 c2 r23 r24 q23 q24 q22 r5 q11 q12 q27 q28 c1 r9 r12 c3 c4 q26 q20 q19 q46 q45 output features low noise, 80 nv p-p (0.1 hz to 10 hz) 3 nv/ hz @ 1 khz low drift, 0.2 v/ c high speed, 17 v/ s slew rate 63 mhz gain bandwidth low input offset voltage, 10 v excellent cmrr, 126 db (common-voltage @ 11 v) high open-loop gain, 1.8 million replaces 725, op-07, se5534 in gains > 5 available in die form general description the OP37 provides the same high performance as the op27, but the design is optimized for circuits with gains greater than five. this design change increases slew rate to 17 v/ m s and gain-bandwidth product to 63 mhz. the OP37 provides the low offset and drift of the op07 plus higher speed and lower noise. offsets down to 25 m v and a maximum drift of 0.6 m v/ c make the OP37 ideal for preci- sion instrumentation applications. exceptionally low noise (e n = 3.5 nv/ @ 10 hz), a low 1/f noise corner frequency of 2.7 hz, and the high gain of 1.8 million, allow accurate high-gain amplification of low-level signals. the low input bias current of 10 na and offset current of 7 na are achieved by using a bias-current cancellation circuit. o ver the military temperature range this typically holds i b and i os to 20 na and 15 na respectively. pin connections 8-lead hermetic dip (z suffix) epoxy mini-dip (p suffix) 8-lead so (s suffix) 8 7 6 5 1 2 3 4 nc = no connect v os trim ?in +in v os trim v+ out nc v? OP37 the output stage has good load driving capability. a guaranteed swing of 10 v into 600 w and low output distortion make the OP37 an excellent choice for professional audio applications. psrr and cmrr exceed 120 db. these characteristics, coupled with long-term drift of 0.2 m v/month, allow the circuit designer to achieve performance levels previously attained only by discrete designs. low-cost, high-volume production of the OP37 is achieved by using on-chip zener-zap trimming. this reliable and stable offset trimming scheme has proved its effectiveness over many years of production history. the OP37 brings low-noise instrumentation-type performance to such diverse applications as microphone, tapehead, and riaa phono preamplifiers, high-speed signal conditioning for data acquisition systems, and wide-bandwidth instrumentation.
rev. b OP37 ? absolute maximum ratings 4 supply voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 v internal voltage (note 1 ) . . . . . . . . . . . . . . . . . . . . . . . . . 22 v output short-circuit duration . . . . . . . . . . . . . . . . . indefinite differential input voltage (note2) . . . . . . . . . . . . . . . . . 0.7 v differential input current (note 2) . . . . . . . . . . . . . . . . 25 ma storage temperature range . . . . . . . . . . . . . ?5 c to +150 c operating temperature range OP37a . . . . . . . . . . . . . . . . . . . . . . . . . . . . ?5 c to +125 c OP37e (z) . . . . . . . . . . . . . . . . . . . . . . . . . . 25 c to +85 c OP37e, op-37f (p) . . . . . . . . . . . . . . . . . . . . . 0 c to 70 c OP37g (p, s, z) . . . . . . . . . . . . . . . . . . . . . 40 c to +85 c lead temperature range (soldering, 60 sec) . . . . . . . . 300 c junction temperature . . . . . . . . . . . . . . . . . . ?5 c to +150 c package type ja 3 jc unit 8-lead hermetic dip (z) 148 16 c/w 8-lead plastic dip (p) 103 43 c/w 8-lead so (s) 158 43 c/w notes 1 for supply voltages less than 22 v, the absolute maximum input voltage is equal to the supply voltage. 2 the OP37? 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 0.7 v, the input current should be limited to 25 ma. 3 ja is specified for worst case mounting conditions, i.e., ja is specified for device in socket for to, cerdip, p-dip, and lcc packages; ja is specified for device soldered to printed circuit board for so package. 4 absolute maximum ratings apply to both dice and packaged parts, unless otherwise noted. ordering guide t a = 25 co perating v os max cerdip plastic temperature ( v) 8-lead 8-lead range 25 OP37az * mil 25 OP37ez OP37ep ind/com 60 OP37fp * ind/com 100 OP37gp xind 100 OP37gz OP37gs xind * not for new design, obsolete, april 2002. caution esd (electrostatic discharge) sensitive device. electrostatic charges as high as 4000 v readily accumulate on the human body and test equipment and can discharge without detection. although the OP37 features proprietary esd protection circuitry, permanent damage may occur on devices subjected to high-energy electrostatic discharges. therefore, proper esd precautions are recommended to avoid performance degradation or loss of functionality. warning! esd sensitive device
rev. b ? OP37 specifications ( v s = 15 v, t a = 25 c, unless otherwise noted.) OP37a/e OP37f OP37g parameter symbol conditions min typ max min typ max min typ max unit input offset voltage v os note 1 10 25 20 60 30 100 m v long-term stability v os /time notes 2, 3 0.2 1.0 0.3 1.5 0.4 2.0 m v/mo input offset current i os 735 950 12 75 na input bias current i b 10 40 12 55 15 80 na input noise voltage e np-p 1 hz to 10 hz 3, 5 0.08 0.18 0.08 0.18 0.09 0.25 m v p-p input noise voltage density e n f o = 10 hz 3 3.5 5.5 3.5 5.5 3.8 8.0 f o = 30 hz 3 3.1 4.5 3.1 4.5 3.3 5.6 nv/ hz f o = 1000 hz 3 3.0 3.8 3.0 3.8 3.2 4.5 input noise current density i n f o = 10 hz 3, 6 1.7 4.0 1.7 4.0 1.7 f o = 30 hz 3, 6 1.0 2.3 1.0 2.3 1.0 pa/ hz f o = 1000 hz 3, 6 0.4 0.6 0.4 0.6 0.4 0.6 input resistance differential mode r in note 7 1.3 6 0.9 4 5 0.7 4 m w input resistance common mode r incm 3 2.5 2 g w input voltage range ivr 11 12.3 11 12.3 11 12.3 v common mode rejection ratio cmrr v cm = 11 v 114 126 106 123 100 120 db power supply rejection ratio pssr v s = 4 v 1 10 1 10 2 20 m v/ v to 18 v large signal voltage gain a vo r l 2 k w , v o = 10 v 1000 1800 1000 1800 700 1500 v/mv r l 1 k w , vo = 10 v 800 1500 800 1500 400 1500 v/mv r l 600 w , v o = 1 v, v s 4 4 250 700 250 700 200 500 v/mv output voltage swing v o r l 2 k w 12.0 13.8 12.0 13.8 11.5 13.5 v r l 600 w 10 11.5 10 11.5 10 11.5 v slew rate sr r l 2k w 4 11 17 11 17 11 17 v/ m s gain bandwidth product gbw f o = 10 khz 4 45 63 45 63 45 63 mhz f o = 1 mhz 40 40 40 mhz open-loop output resistance r o v o = 0, i o = 0 70 70 70 w power consumption p d v o = 0 90 140 90 140 100 170 mw offset adjustment range r p = 10 k w 4 4 4mv notes 1 input offset voltage measurements are performed by automated test equipment approximately 0.5 seconds after application of powe r. a/e grades guaranteed fully warmed up. 2 long term input offset voltage stability refers to the average trend line of v os 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 2.5 m v?efer to typical performance curve. 3 sample tested. 4 guaranteed by design. 5 see test circuit and frequency response curve for 0.1 hz to 10 hz tester. 6 see test circuit for current noise measurement. 7 guaranteed by input bias current.
rev. b ? OP37?pecifications electrical characteristics OP37a OP37c parameter symbol conditions min typ max min typ max unit input offset voltage v os note 1 10 25 30 100 m v average input offset drift tcv os note 2 tcv osn note 3 0.2 0.6 0.4 1.8 m v/ c input offset current i os 15 50 30 135 na input bias current i b 20 60 35 150 na input voltage range ivr 10.3 11.5 10.2 11.5 v common mode rejection ratio cmrr v cm = 10 v 108 122 94 116 db power supply rejection ratio psrr v s = 4.5 v to 18 v 2 16 4 51 m v/ v large-signal voltage gain a vo r l 2 k w , v o = 10 v 600 1200 300 800 v/mv output voltage swing v o r l 2 k w 11.5 13.5 10.5 13.0 v electrical characteristics OP37e OP37f OP37c parameter symbol conditions min typ max min typ max min typ max unit input offset voltage v os 20 50 40 140 55 220 m v average input offset drift tcv os note 2 tcv osn note 3 0.2 0.6 0.3 1.3 0.4 1.8 m v/ c input offset current i os 10 50 14 85 20 135 na input bias current i b 14 60 18 95 25 150 na input voltage range ivr 10.5 11.8 10.5 11.8 10.5 11.8 v common mode rejection ratio cmrr v cm = 10 v 108 122 100 119 94 116 db power supply rejection ratio psrr v s = 4.5 v to 18 v 2 15 2 16 4 32 m v/ v large-signal voltage gain a vo r l 2 k w , vo = 10 v 750 1500 700 1300 450 1000 v/mv output voltage swing v o r l 2 k w 11.7 13.6 11.4 13.5 11 13.3 v notes 1 input offset voltage measurements are performed by automated test equipment approximately 0.5 seconds after application of powe r. a/e grades guaranteed fully warmed up. 2 the tc vos performance is within the specifications unnulled or when nulled withr p = 8 k w to 20 k w . tc vos is 100% tested for a/e grades, sample tested for f/g grades. 3 guaranteed by design. ( v s = 15 v, ?5 c < t a < +125 c, unless otherwise noted.) (v s = 15 v, ?5 c < t a < +85 c for OP37ez/fz, 0 c < t a < 70 c for OP37ep/fp, and ?0 c < t a < +85 c for OP37gp/gs/gz, unless otherwise noted.)
rev. b OP37 ? wafer test limits OP37nt OP37n OP37gt OP37g OP37gr parameter symbol conditions limit limit limit limit limit unit input offset voltage v os note 1 60 35 200 60 100 m v max input offset current i os 50 35 85 50 75 na max input bias current i b 60 40 95 55 80 na max input voltage range ivr 10.3 11 10.3 11 11 v min common mode rejection ratio cmrr v cm = 11 v 108 114 100 106 100 db min power supply rejection ratio psrr t a = 25 c, v s = 4 v to 18 v 10 10 1 01020 m v/v max t a = 125 c, v s = 4.5 v to 18 v 16 20 m v/v max large-signal voltage gain a vo r l 2 k w , v o = 10 v 600 1000 500 1000 700 v/mv min r l 1 k w , v o = 10 v 800 800 v/mv min output voltage swing v o r l 2 k w 11.5 12 11 12 11.5 v min r l 600 k w 10 10 10 v min power consumption p d v o = 0 140 140 170 mw max notes for 25 c characterlstics of OP37nt and OP37gt devices, see OP37n and OP37g characteristics, respectively. electrical tests are performed at wafer probe to the limits shown. due to variations in assembly methods and normal yield loss, yield after packaging is not guaranteed for standard product dice. consult factory to negotiate specifications based on dice lot qualification through sample lot assem bly and testing. (v s = 15 v, t a = 25 c for OP37n, OP37g, and OP37gr devices; t a = 125 c for OP37nt and OP37gt devices, unless otherwise noted.) binding diagram 1 2 3 4 6 8 7 1427u 1990 1. null 2. (?) input 3. (+) input 4. v? 6. output 7. v+ 8. null
rev. b OP37 ? t ypical electrical characteristics OP37nt OP37n OP37gt OP37g OP37gr parameter symbol conditions typical typical typical typical typical unit average input offset voltage drift tcv os or nulled or tcv osn unnulled r p = 8 k w to 20 k w 0.2 0.2 0.3 0.3 0.4 m v/ c average input offset current drift tci os 80 80 130 130 180 pa/ c average input bias current drift tci b 100 100 160 160 200 pa/ c input noise voltage density e n f o = 10 hz 3.5 3.5 3.5 3.5 3.8 nv/ hz f o = 30 hz 3.1 3.1 3.1 3.1 3.3 nv/ hz f o = 1000 hz 3.0 3.0 3.0 3.0 3.2 nv/ hz input noise current density i n f o = 10 hz 1.7 1.7 1.7 1.7 1.7 pa/ hz f o = 30 hz 1.0 1.0 1.0 1.0 1.0 pa/ hz f o = 1000 hz 0.4 0.4 0.4 0.4 0.4 pa/ hz input noise voltage e n p-p 0.1 hz to 10 hz 0.08 0.08 0.08 0.08 0.09 m v p-p slew rate sr r l 2k w 17 17 17 17 17 v/ m s gain bandwidth product gbw f o = 10 khz 63 63 63 63 63 mhz (v s = 15 v, t a = 25 c, unless otherwise noted.)
rev. b ? OP37 frequency ? hz gain ? db 100 0.01 90 80 70 60 50 0.1 1 10 100 40 30 test time of 10sec must be used to limit low frequency (<0.1hz) gain. tpc 1. noise-tester frequency response (0.1 hz to 10 hz) b andwidth ? hz rms voltage noise ? v 10 100k 1 0.1 0.01 100 1k 10k t a = 25 c v s = 15v tpc 4. input wideband voltage noise vs. bandwidth (0.1 hz to frequency indicated) to ta l supply voltage (v+ ? v?) ? volts vo ltag e n oise ? nv/ hz 5 4 1 010 40 20 30 3 2 t a = 25 c at 10hz at 1khz tpc 7. voltage noise density vs. supply voltage frequency ? hz 10 1 t a = 25 c v s = 15v 9 8 7 6 5 4 3 2 1 10 100 1k vo ltag e n oise ? nv/ hz i/f corner = 2.7hz tpc 2. voltage noise density vs. frequency source resistance ? 100 1 10k 100 1k total n oise ? nv/ hz 10 t a = 25 c v s = 15v r2 r1 r s ? 2r1 at 1khz at 10hz resistor noise only tpc 5. total noise vs. source resistance frequency ? hz current noise ? pa/ hz 10.0 0.1 10 10k 1.0 100 1k i/f corner = 140hz tpc 8. current noise density vs. frequency frequency ? hz 100 1 1 10 100 1k vo ltag e n oise ? nv/ hz 10 low noise a udio op amp instrumentation range to dc a udio range to 20khz i/f corner 741 OP37 i/f corner i/f corner = 2.7hz tpc 3. a comparison of op amp voltage noise spectra temperature ? c vo ltag e n oise ? nv/ hz 5 ?50 ?25 0 25 50 75 100 125 4 3 2 1 at 10hz at 1khz v s = 15v tpc 6. voltage noise density vs. temperature to ta l supply voltage ? volts supply current ? ma 5.0 5 t a = +125 c 4.0 3.0 2.0 1.0 15 25 35 45 t a = +25 c t a = ?55 c tpc 9. supply current vs. supply voltage t ypical performance characteristics
rev. b OP37 ? temperature ? c offset voltage ? v 60 ?75 40 20 0 ?20 ?40 ?60 ?50 ?25 0 25 50 75 100 125 150 175 50 10 ?30 ?70 30 ?10 ?50 trimming with 10k pot does not change tcv os OP37c OP37b OP37a OP37b OP37a OP37a OP37b OP37c tpc 10. offset voltage drift of eight representative units vs. temperature time ? seconds open-loop gain ? db 30 ?20 5 0 02040 60 80 100 25 20 15 10 t a = 25 c t a = 70 c device immersed in 70 c oil bath thermal shock response band v s = +15v tpc 13. offset voltage change due to thermal shock frequency ? hz open-loop voltage gain ? db 140 1 t a = 25 c v s = 15v r l 2k 120 100 80 60 40 20 0 10 10 2 10 3 10 4 10 5 10 6 10 7 10 8 tpc 16. open-loop gain vs. frequency time ? months change in offset voltage ? v 6 0 2 ?2 ?6 4 0 ?2 ?6 1 234567 4 0 ?4 6 2 ?4 tpc 11. long-term offset voltage drift of six representative units temperature ? c input bias current ? na ?50 40 20 0 ?25 0 25 50 75 100 125 150 50 30 10 v s = +15v OP37a OP37b OP37c tpc 14. input bias current vs. temperature temperature ? c slew rate ? v/ s ?50 70 30 10 ?25 0 25 50 75 100 125 80 60 20 v s = 15v slew m 65 25 75 55 15 phase margin ? deg 90 85 80 75 70 65 60 55 50 45 40 gain-bandwidth product ? mhz f = 10khz gbw tpc 17. slew rate, gain bandwidth product, phase margin vs. temperature time after power on ? minutes change in input offset voltage ? v 10 1 01 4 23 5 t a = 25 c v s = 15v 5 OP37c/g OP37f OP37a/e tpc 12. warm up offset voltage drift temperature ? c input offset current ? na ?75 50 0 ?50 ?25 0 25 50 75 100 125 v s = 15v 40 30 20 10 OP37a OP37b OP37c tpc 15. input offset current vs. temperature frequency ? hz 60 100k 1m 10m 100m gain ? db 50 40 30 20 10 0 ?10 t a = 25 c v s = 15v a v = 5 ?80 ?100 ?120 ?140 ?160 ?180 ?200 ?220 phase shift ? degrees phase margin = 71 tpc 18. gain, phase shift vs. frequency
rev. b ? OP37 to ta l supply voltage ? volts open-loop gain ? v/ v 2.5 010 40 20 30 t a = 25 c 50 2.0 1.5 1.0 0.5 0 r l = 2k r l = 1k tpc 19. open-loop voltage gain vs. supply voltage capacitive load ? pf percent overshoot 80 60 0 0500 2000 1000 1500 40 20 v s = 15v v in = 20mv a v = +5 (1k , 250 ) tpc 22. small-signal overshoot vs. capacitive load time from output shorted to ground ? minutes short-circuit current ? ma 60 01 4 23 5 50 40 30 20 10 t a = 25 c v s = 15v i sc (+) i sc (?) tpc 25. short-circuit current vs. time frequency ? hz 28 10 4 10 5 10 6 10 7 peak-to-peak amplitude ? volts 24 20 16 12 8 4 0 t a = 25 c v s = 15v tpc 20. maximum output swing vs. frequency 5v 1s +10v 0v ?0v t a = 25 c v s = 15v a v = +5 (1k , 250 ) tpc 23. large-signal transient response frequency ? hz cmrr ? db 140 1k 120 100 80 60 40 10k 100k 1m 10m v s = 15v t a = 25 c v cm = 10v tpc 26. cmrr vs. frequency load resistance ? maximum output ? volts 18 100 1k 10k 16 14 12 10 8 6 4 2 0 ?2 t a = 25 c v s = 15v positive swing negative swing tpc 21. maximum output voltage vs. load resistance 20mv 200ns + 50mv 0v ?0mv t a = 25 c v s = 15v a v = +5 (1k , 250 ) tpc 24. small-signal transient response supply voltage ? volts common-mode range ? volts 16 0 5 12 8 4 0 ?4 10 15 20 ?8 ?12 ?16 t a = ?55 c t a = +125 c t a = +25 c t a = +25 c t a = ?55 c t a = +125 c tpc 27. common-mode input range vs. supply voltage
rev. b OP37 ?0 op12 OP37 d.u.t. 100k 4.3k 4.7 f 2k 24.3k vo ltag e gain = 50,000 2.2 f 22 f 110k scope 1 r in = 1m 0.1 f 10 100k 0.1 f tpc 28. noise test circuit (0.1 hz to 10 hz) frequency ? hz power supply rejection ratio ? db 140 1 t a = 25 c 120 100 80 60 40 20 0 10 100 1k 10k 100k 1m 10m 100m 160 positive swing negative swing tpc 31. psrr vs. frequency 1 sec/div tpc 29. low-frequency noise load resistance ? 19 100 1k 10k 100k slew rate ? v/ v t a = 25 c v s = 15v a v = 5 v o = 20v p-p 18 17 16 15 tpc 32. slew rate vs. load load resistance ? 2.4 100 1k 10k 100k open-loop voltage gain ? v/ v t a = 25 c v s = 15v 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 tpc 30. open-loop voltage gain vs. load resistance supply voltage ? volts vo ltag e n oise ? v/ s 20 3 15 10 5 0 t a = 25 c a vcl = 5 6 9 12 15 18 21 fa l l rise tpc 33. slew rate vs. supply voltage
rev. b OP37 ?1 applications information OP37 series units may be inserted directly into 725 and op07 sockets with or without removal of external compensation or nulling components. additionally, the OP37 may be fitted to unnulled 741type sockets; however, if conventional 741 nulling circuitry is in use, it should be modified or removed to ensure correct OP37 operation. OP37 offset voltage may be nulled to zero (or other desired setting) using a potentiometer (see figure 1). the OP37 provides stable operation with load capacitances of up to 1000 pf and 10 v swings; larger capacitances should be decoupled with a 50 w resistor inside the feedback loop. closed loop gain must be at least five. for closed loop gain between five to ten, the designer should consider both the op27 and the OP37. for gains above ten, the OP37 has a clear advantage over the unity stable op27. thermoelectric voltages generated by dissimilar metals at the input terminal contacts can degrade the drift performance. best operation will be obtained when both input contacts are main- tained at the same temperature. 10k r p OP37 v+ output v? + ? figure 1. offset nulling circuit offset voltage adjustment the input offset voltage of the OP37 is trimmed at wafer level. however, if further adjustment of v os is necessary, a 10 k w trim potentiometer may be used. tcv os is not degraded (see offset nulling circuit). other potentiometer values from 1 k w to 1 m w can be used with a slight degradation (0.1 m v/ r c to 0.2 m v/ r c) of tcv os . trimming to a value other than zero creates a drift of approximately (v os /300) m v/ r c. for example, the change in tcv os will be 0.33 m v/ r c if v os is adjusted to 100 m v. the offset voltage adjustment range with a 10 k w potentiometer is 4 mv. if smaller adjustment range is required, the nulling sensitivity can be reduced by using a smaller pot in conjunction with fixed resistors. for example, the network shown in figure 2 will have a 280 m v ad- justment range. 1 8 4.7k 4.7k 1k pot v+ figure 2. offset voltage adjustment OP37 ?18v +18v figure 3. burn-in circuit noise measurements to measure the 80 nv peak-to-peak noise specification of the OP37 in the 0.1 hz to 10 hz range, the following precautions must be observed: y the device has to be warmed-up for at least five minutes. as shown in the warm-up drift curve, the offset voltage typically changes 4 m v due to increasing chip temperature after power up. in the ten second measurement interval, these temperature- induced effects can exceed tens of nanovolts. y for similar reasons, the device has to be well-shielded from air currents. shielding minimizes thermocouple effects. y sudden motion in the vicinity of the device can also ?eedthrough?to increase the observed noise. y the test time to measure 0.1 hz to l0 hz noise should not exceed 10 seconds. as shown in the noise-tester frequency response curve, the 0.1 hz corner is defined by only one zero. the test time of ten seconds acts as an additional zero to eliminate noise contributions from the frequency band below 0.1 hz. y a noise-voltage-density test is recommended when measuring noise on a large number of units. a 10 hz noise-voltage-density measurement will correlate well with a 0.1 hz-to-10 hz peak-to-peak noise reading, since both results are determined by the white noise and the location of the 1/f corner frequency. optimizing linearity best linearity will be obtained by designing for the minimum output current required for the application. high gain and excellent linearity can be achieved by operating the op amp with a peak output current of less than 10 ma. instrumentation amplifier a three-op-amp instrumentation amplifier, shown in figure 4, provides high gain and wide bandwidth. the input noise of the circuit below is 4.9 nv/ hz . the gain of the input stage is set at 25 and the gain of the second stage is 40; overall gain is 1000. the amplifier bandwidth of 800 khz is extraordinarily good for a precision instrumentation amplifier. set to a gain of 1000, this yields a gain bandwidth product of 800 mhz. the full-power bandwidth for a 20 v p-p output is 250 khz. potentiometer r7 provides quadrature trimming to optimize the instrumentation amplifier? ac common- mode rejection. r7 100k c1 100pf r1 5k 0.1% r3 390 r2 100 r4 5k 0.1% input (+) input (?) r5 500 0.1% r6 500 0.1% r8 20k 0.1% r9 19.8k r10 500 v out notes: trim r2 for a vcl = 1000 trim r10 for dc cmrr trim r7 for minimum v out at v cm = 20v p-p, 10khz + ? OP37 + ? OP37 + ? OP37 figure 4a. instrumentation amplifier
rev. b OP37 ?2 frequency ? hz 140 10 cmrr ? db 100 1k 10k 100k 1m 120 100 80 60 40 t a = 25 c v s = 15v v cm = 20v p-p ac trim @ 10khz r s = 0 r s = 100 , 1k unbalanced r s = 1k ba lanced r s = 0 figure 4b. cmrr vs. frequency comments on noise the OP37 is a very low-noise monolithic op amp. the outstanding input voltage noise characteristics of the OP37 are achieved mainly by operating the input stage at a high quiescent current. the input bias and offset currents, which would normally increase, are held to reasonable values by the input bias current cancellation circuit. the OP37a/e has i b and i os of only 40 na and 35 na respectively at 25 c. this is particularly important when the input has a high source resistance. in addition, many audio amplifier designers prefer to use direct coupling. the high i b . tcv os of previous designs have made direct coupling difficult, if not impossible, to use. r s ? source resistance ? 10 50 10k total n oise ? nv/ hz 5 500 1k 5k 1 100 50 100 50k r s1 r s2 1 r s unmatched e.g. r s = r s1 = 10k , r s2 = 0 2 r s matched e.g. r s = 10k , r s1 = r s2 = 5k op07 5534 op27/37 register noise only op08/108 1 2 figure 5. noise vs. resistance (including resistor noise @ 1000 hz) voltage noise is inversely proportional to the square-root of bias current, but current noise is proportional to the square-root of bias current. the OP37? noise advantage disappears when high source-resistors are used. figures 5, 6, and 7 compare op-37 observed total noise with the noise performance of other devices in different circuit applications. total noise = [( voltage noise)2 + (current noise rs)2 + (resistor noise_]1/2 figure 5 shows noise versus source resistance at 1000 hz. the same plot applies to wideband noise. to use this plot, just multiply the vertical scale by the square-root of the bandwidth. r s ? source resistance ? 100 50 10k p-p noise ? nv 50 500 1k 5k 10 1k 500 100 50k r s1 r s2 1 r s unmatched e.g. r s = r s1 = 10k , r s2 = 0 2 r s matched e.g. r s = 10k , r s1 = r s2 = 5k op07 5534 op27/37 register noise only op08/108 1 2 figure 6. peak-to-peak noise (0.1 hz to 10 hz) vs. source resistance (includes resistor noise) at r s < 1 k w key the OP37? low voltage noise is maintained. with r s < 1 k w , total noise increases, but is dominated by the resistor noise rather than current or voltage noise. it is only beyond rs of 20 k w that current noise starts to dominate. the argument can be made that current noise is not important for applications with low to-moderate source resistances. the crossover between the OP37 and op07 and op08 noise occurs in the 15 k w to 40 k w region. r s ? source resistance ? 10 50 10k total n oise ? nv/ hz 5 500 1k 5k 1 100 50 100 50k op07 5534 op27/37 register noise only op08/108 r s1 r s2 1 r s unmatched e.g. r s = r s1 = 10k , r s2 = 0 2 r s matched e.g. r s = 10k , r s1 = r s2 = 5k 1 2 figure 7. noise vs. source resistance (includes resistor noise @ 10 hz) figure 6 shows the 0.1 hz to 10 hz peak-to-peak noise. here the picture is less favorable; resistor noise is negligible, current noise becomes important because it is inversely proportional to the square-root of frequency. the crossover with the op07 occurs in the 3 k w to 5 k w range depending on whether bal- anced or unbalanced source resistors are used (at 3 k w the i b . i os error also can be three times the v os spec.). therefore, for low-frequency applications, the op07 is better than the op27/37 when rs > 3 k w . the only exception is when gain error is important. figure 7 illustrates the 10 hz noise. as expected, the results are between the previous two figures. for reference, typical source resistances of some signal sources are listed in table i.
rev. b OP37 ?3 table i. source device impedance comments straln gauge <500 w typically used in low- frequency applications. magnetic <1500 w low i b very important to reduce tapehead set-magnetization problems when direct coupling is used. OP37 i b can be neglected. magnetic <1500 w similar need for low i b in direct phonograph coupled applications. OP37 will not cartridges introduce any self-magnetization problem. linear variable <1500 w used in rugged servo-feedback differential applications. bandwidth of interest transformer is 400 hz to 5 khz. audio applications the following applications information has been abstracted from a pmi article in the 12/20/80 issue of electronic design magazine and updated. ca 150pf a1 op27 ra 47.5k r1 97.6k moving magnet cartridge input r2 7.87k r3 100 c1 0.03 f c2 0.01 f c3 0.47 f r4 75k ++ c4 (2) 220 f lf rolloff out in output r5 100k g = 1khz gain = 0.101 ( ) r1 r3 1 + = 98.677 (39.9db) as shown figure 8. phono pre-amplifier circuit figure 8 is an example of a phono pre-amplifier circuit using the op27 for a1; r1-r2-c1-c2 form a very accurate riaa net- work with standard component values. the popular method to accomplish riaa phono equalization is to employ frequency- dependent feedback around a high-quality gain block. properly chosen, an rc network can provide the three necessary time constants of 3180 m s, 318 m s, and 75 m s. 1 for initial equalization accuracy and stability, precision metal- film resistors and film capacitors of polystyrene or polypropylene are recommended since they have low voltage coefficients, dissipation factors, and dielectric absorption. 4 (high-k ceramic capacitors should be avoided here, though low-k ceramics such as npo types, which have excellent dissipation factors, and somewhat lower dielectric absorption?an be considered for small values or where space is at a premium.) the OP37 brings a 3.2 nv/ hz voltage noise and 0.45 pa/ hz current noise to this circuit. to minimize noise from other sources, r3 is set to a value of 100 w , which generates a voltage noise of 1.3 nv/ hz . the noise increases the 3.2 nv/ hz of the amplifier by only 0.7 db. with a 1 k w source, the circuit noise measures 63 db below a 1 mv reference level, unweighted, in a 20 khz noise bandwidth. gain (g) of the circuit at 1 khz can be calculated by the expression: g r r =+ ? ? ? 0 101 1 1 3 . for the values shown, the gain is just under 100 (or 40 db). lower gains can be accommodated by increasing r3, but gains higher than 40 db will show more equalization errors because of the 8 mhz gain bandwidth of the op27. this circuit is capable of very low distortion over its entire range, generally below 0.01% at levels up to 7 v rms. at 3 v output levels, it will produce less than 0.03% total harmonic distortion at frequencies up to 20 khz. capacitor c3 and resistor r4 form a simple ? db per octave rumble filter, with a corner at 22 hz. as an option, the switch selected shunt capacitor c4, a nonpolarized electrolytic, bypasses the low-frequency rolloff. placing the rumble filter? high-pass action after the preamp has the desirable result of discriminating against the riaa amplified low frequency noise components and pickup-produced low-frequency disturbances. a preamplifier for nab tape playback is similar to an riaa phono preamp, though more gain is typically demanded, along with equalization requiring a heavy low-frequency boost. the circuit in figure 8 can be readily modified for tape use, as shown by figure 9. ca ra r1 33k t ape head 0.47 f 0.01 f r2 5k 100k 15k t1 = 3180 s t2 = 50 s OP37 + ? figure 9. tape-head preamplifier while the tape-equalization requirement has a flat high frequency gain above 3 khz (t 2 = 50 m s), the amplifier need not be stabilized for unity gain. the decompensated OP37 provides a greater bandwidth and slew rate. for many applications, the idealized time constants shown may require trimming of ra and r2 to optimize frequency response for non ideal tape head perfor- mance and other factors. 5 the network values of the configuration yield a 50 db gain at 1 khz, and the dc gain is greater than 70 db. thus, the worst-case out- put offset is just over 500 mv. a single 0.47 m f output capacitor can block this level without affecting the dynamic range. the tape head can be coupled directly to the amplifier input, since the worst-case bias current of 85 na with a 400 mh, 100 m in. head (such as the prb2h7k) will not be troublesome. one potential tape-head problem is presented by amplifier bias- current transients which can magnetize a head. the op27 and
rev. b OP37 ?4 OP37 are free of bias-current transients upon power up or power down. however, it is always advantageous to control the speed of power supply rise and fall, to eliminate transients. in addition, the dc resistance of the head should be carefully controlled, and preferably below 1 k w . for this configuration, the bias-current induced offset voltage can be greater than the 170 pv maximum offset if the head resistance is not sufficiently controlled. a simple, but effective, fixed-gain transformerless microphone preamp (figure 10) amplifies differential signals from low imped- ance microphones by 50 db, and has an input impedance of 2 k w . because of the high working gain of the circuit, an OP37 helps to preserve bandwidth, which will be 110 khz. as the OP37 is a decompensated device (minimum stable gain of 5), a dummy resistor, r p , may be necessary, if the microphone is to be unplugged. otherwise the 100% feedback from the open input may cause the amplifier to oscillate. OP37 + ? r3 316k rp 30k r1 1k r4 316k r2 1k r7 10k r6 100 output r3 r1 r4 r2 = low impedance microphone input (z = 50 to 200 ) c1 5 f figure 10. fixed gain transformerless microphone preamp common-mode input-noise rejection will depend upon the match of the bridge-resistor ratios. either close-tolerance (0.1%) types should be used, or r4 should be trimmed for best cmrr. all resistors should be metal-film types for best stability and low noise. noise performance of this circuit is limited more by the input resistors r1 and r2 than by the op amp, as r1 and r2 each generate a 4 nv/ hz noise, while the op amp generates a 3.2 nv/ hz noise. the rms sum of these predominant noise sources will be about 6 nv/ hz , equivalent to 0.9 m v in a 20 khz noise band- width, or nearly 61 db below a l mv input signal. measurements confirm this predicted performance. for applications demanding appreciably lower noise, a high quality microphone-transformer-coupled preamp (figure 11) incorporates the internally compensated. t1 is a je-115k-e 150 w /15 k w transformer which provides an optimum source resistance for the op27 device. the circuit has an overall gain of 40 db, the product of the transformer? voltage setup and the op amp? voltage gain. gain may be trimmed to other levels, if desired, by adjusting r2 or r1. because of the low offset voltage of the op27, the output offset of this circuit will be very low, 1.7 mv or less, for a 40 db gain. the typical output blocking capacitor can be eliminated in such cases, but is desirable for higher gains to eliminate switching transients. a1 op27 r3 100 r1 121 r2 1100 c2 1800pf output 150 source t1 * t1 ? jensen je ? 115k ? e jensen transformers 10735 burbank blvd. n. hollywood, ca 91601 * figure 11. microphone transformer coupled preamp capacitor c2 and resistor r2 form a 2 m s time constant in this circuit, as recommended for optimum transient response by the transformer manufacturer. with c2 in use, a1 must have unity-gain stability. for situations where the 2 m s time con- stant is not necessary, c2 can be deleted, allowing the faster OP37 to be employed. some comment on noise is appropriate to understand the capability of this circuit. a 150 w resistor and r1 and r2 gain resistors connected to a noiseless amplifier will generate 220 nv of noise in a 20 khz bandwidth, or 73 db below a 1 mv reference level. any practical amplifier can only approach this noise level; it can never exceed it. with the op27 and t1 specified, the additional noise degradation will be close to 3.6 db (or ?9.5 referenced to 1 mv). references 1. lipshitz, s.p, ?n riaa equalization networks,?jaes, vol. 27, june 1979, p. 458-4s1. 2. jung, w.g., ic op amp cookbook, 2nd ed., h.w. sams and company, 1980. 3. jung, w.g., audio /c op amp applications, 2nd ed., h.w. sams and com- pany, 1978. 4. jung, w.g., and marsh, r.m., ?icking capacitors.?audio, february & march, 1980. 5. otala, m., ?eedback-generated phase nonlinearity in audio amplifiers, london aes convention, march 1980, preprint 197b. 6. stout, d.f., and kaufman, m., handbook of operational amplifier circuit design, new york, mcgraw hill, 1976.
rev. b OP37 ?5 outline dimensions 8-lead ceramic dip ?glass hermetic seal [cerdip] (q-8) dimensions shown in inches and (millimeters) 1 4 85 0.310 (7.87) 0.220 (5.59) pin 1 0.005 (0.13) min 0.055 (1.40) max 0.100 (2.54) bsc 15 0 0.320 (8.13) 0.290 (7.37) 0.015 (0.38) 0.008 (0.20) seating plane 0.200 (5.08) max 0.405 (10.29) max 0.150 (3.81) min 0.200 (5.08) 0.125 (3.18) 0.023 (0.58) 0.014 (0.36) 0.070 (1.78) 0.030 (0.76) 0.060 (1.52) 0.015 (0.38) controlling dimensions are in inches; millimeters dimensions (in parentheses) are rounded-off inch equivalents for reference only and are not appropriate for use in design 8-lead plastic dual-in-line package [pdip] (n-8) dimensions shown in inches and (millimeters) seating plane 0.015 (0.38) min 0.180 (4.57) max 0.150 (3.81) 0.130 (3.30) 0.110 (2.79) 0.060 (1.52) 0.050 (1.27) 0.045 (1.14) 8 1 4 5 0.295 (7.49) 0.285 (7.24) 0.275 (6.98) 0.100 (2.54) bsc 0.375 (9.53) 0.365 (9.27) 0.355 (9.02) 0.150 (3.81) 0.135 (3.43) 0.120 (3.05) 0.015 (0.38) 0.010 (0.25) 0.008 (0.20) 0.325 (8.26) 0.310 (7.87) 0.300 (7.62) 0.022 (0.56) 0.018 (0.46) 0.014 (0.36) controlling dimensions are in inches; millimeter dimensions (in parentheses) are rounded-off inch equivalents for reference only and are not appropriate for use in design compliant to jedec standards mo-095aa 8-lead standard small outline package [soic] narrow body (rn-8) dimensions shown in millimeters and (inches) 0.25 (0.0098) 0.19 (0.0075) 1.27 (0.0500) 0.41 (0.0160) 0.50 (0.0196) 0.25 (0.0099) 45 8 0 1.75 (0.0688) 1.35 (0.0532) seating plane 0.25 (0.0098) 0.10 (0.0040) 85 4 1 5.00 (0.1968) 4.80 (0.1890) 4.00 (0.1574) 3.80 (0.1497) 1.27 (0.0500) bsc 6.20 (0.2440) 5.80 (0.2284) 0.51 (0.0201) 0.33 (0.0130) coplanarity 0.10 controlling dimensions are in millimeters; inch dimensions (in parentheses) are rounded-off millimeter equivalents for reference only and are not appropriate for use in design compliant to jedec standards ms-012aa
rev. b ?6 c00319??2/02(b) printed in u.s.a. revision history location page 12/02?ata sheet changed from rev. a to rev. b. edits to binding diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 edits to caption for tpc 31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 edits to applications information section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 added caption to figure 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 added caption to figures 4a and 4b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 added caption to figures 8?1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 updated outline dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2/02?ata sheet changed from rev. 0 to rev. a. edits to features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 edits to ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 edits to pin connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 edits to absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 edits to package type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 edits to electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 edits to applications information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 OP37

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