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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
Low Noise, Precision, High Speed Operational Amplifier (A VCL > 5) OP37
The output stage has good load driving capability. A guaranteed swing of 10 V into 600 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 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.
PIN CONNECTIONS 8-Lead Hermetic DIP (Z Suffix) Epoxy Mini-DIP (P Suffix) 8-Lead SO (S Suffix)
VOS TRIM 1 -IN 2 +IN 3 V- 4
8 7 6 5
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/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 V and drift of 0.6 V/C maximum make the OP37 ideal for precision instrumentation applications. Exceptionally low noise (en= 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. Over the military temperature range this typically holds IB and IOS to 20 nA and 15 nA respectively.
OP37
VOS TRIM V+ OUT NC
NC = NO CONNECT
SIMPLIFIED SCHEMATIC
V+ R3 Q6 R1* 1 8 R4 R2* C2 Q22 Q21 R23 Q23 R24 Q24 R9 Q20 Q1A NON-INVERTING INPUT (+) Q3 INVERTING INPUT (-) *R1 AND R2 ARE PERMANENTLY ADJUSTED AT WAFER TEST FOR MINIMUM OFFSET VOLTAGE. V- Q11 Q12 Q27 Q28 Q26 Q45 Q1B Q2B Q2A R5 C3 R12 C4 Q19 OUTPUT C1 Q46
VOS ADJ.
REV. A
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. 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 (c) Analog Devices, Inc., 2002
OP37
ABSOLUTE MAXIMUM RATINGS 4 ORDERING GUIDE
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 . . . . . . . . . . . . . -65C to +150C Operating Temperature Range OP37A . . . . . . . . . . . . . . . . . . . . . . . . . . . -55C to +1 25C OP37E (Z) . . . . . . . . . . . . . . . . . . . . . . . . . . -25C to +85C OP37E, OP-37F (P) . . . . . . . . . . . . . . . . . . . . . 0C to 70C OP37G (P, S, Z) . . . . . . . . . . . . . . . . . . . . . -40C to +85C Lead Temperature Range (Soldering, 60 sec) . . . . . . . . 300C Junction Temperature . . . . . . . . . . . . . . . . . . -45C to +150C Package Type
3 JA JC
TA = 25C VOS MAX (V) 25 25 60 100 100
CerDIP 8-Lead OP37AZ* OP37EZ
Plastic 8-Lead OP37EP OP37FP* OP37GP OP37GS
Operating Temperature Range MIL IND/COM IND/COM XIND XIND
OP37GZ
*Not for new design, obsolete, April 2002.
Unit C/W C/W C/W
8-Lead Hermetic DIP (Z) 148 8-Lead Plastic DIP (P) 103 8-Lead SO (S) 158
16 43 43
NOTES 1 For supply voltages less than 22 V, the absolute maximum input voltage is equal to the supply voltage. 2 The OP37's 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.
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
-2-
REV. A
OP37
SPECIFICATIONS ( V =
S
15 V, TA = 25 C, unless otherwise noted.)
Min OP37A/E Typ Max 10 0.2 7 10 25 1.0 35 40 0.18 5.5 4.5 3.8 4.0 2.3 0.6 0.9 Min OP37F Typ Max 20 0.3 9 12 0.08 3.5 3.1 3.0 1.7 1.0 0.4 45 2.5 11 106 10 12.3 123 1 10 11 100 60 1.5 50 55 0.18 5.5 4.5 3.8 4.0 2.3 0.6 0.7 Min OP37G Typ Max 30 0.4 12 15 0.09 3.8 3.3 3.2 1.7 1.0 0.4 4 2 12.3 120 2 20 100 2.0 75 80 0.25 8.0 5.6 4.5 Unit V V/Mo nA nA V p-p nV/ Hz
Parameter Input Offset Voltage Long-Term Stability Input Offset Current Input Bias Current Input Noise Voltage Input Noise Voltage Density Input Noise CurrentDensity Input Resistance Differential Mode Input Resistance Common Mode Input Voltage Range Common Mode Rejection Ratio Power Supply Rejection Ratio Large Signal Voltage Gain
Symbol VOS VOS/Time IOS IB enp-p en
Conditions Note 1 Notes 2, 3
1 Hz to 10 Hz3, 5 fO = 10 Hz3 fO = 30 Hz3 fO = 1000 Hz3 fO = 10 Hz3, 6 fO = 30 Hz3, 6 fO = 1000 Hz3, 6 Note 7 1.3
0.08 3.5 3.1 3.0 1.7 1.0 0.4 6 3 11 12.3 126 1
iN
pA/ Hz 0.6 M G V dB V/ V
RIN RINCM IVR CMRR PSSR AVO
VCM = 11 V VS = 4 V to 18 V RL 2 k, VO = 10 V RL 1 k, Vo = 10 V RL 600 , VO = 1 V, V S 44 RL 2 k RL 600 RL 2k 4 fO = 10 kHz4 fO = 1 MHz VO = 0, IO = 0 VO = 0 RP = 10 k
114
1000 800 250
1800 1500 700
1000 800 250
1800 1500 700
700 400 200
1500 1500 500
V/m V V/m V V/m V V V V/s MHz MHz 170 mW mV
Output Voltage Swing
VO
Slew Rate SR Gain Bandwidth Product GBW Open-Loop Output Resistance RO Power Consumption Pd Offset Adjustment Range
12.0 13.8 10 11.5 11 17 45 63 40 70 90 4 140
12.0 13.8 10 11.5 11 17 45 63 40 70 90 4 140
11.5 13.5 10 11.5 11 17 45 63 40 70 100 4
NOTES 1 Input offset voltage measurements are performed by automated test equipment approximately 0.5 seconds after application of power. 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 V--refer 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. A
-3-
OP37-SPECIFICATIONS
Electrical Characteristics ( V =
S
15 V, -55 C < TA < +125 C, unless otherwise noted.)
Min OP37A Typ 10 25 Max Min 30 OP37C Typ 100 Max V 1.8 nA 150 nA V dB V/ V V/m V V V/C Unit
Parameter Input Offset Voltage Average Input Offset Drift Input Offset Current Input Bias Current Input Voltage Range Common Mode Rejection Ratio Power Supply Rejection Ratio Large-Signal Voltage Gain Output Voltage Swing
Symbol VOS TCVOS TCVOSN IOS IB IVR CMRR PSRR
Conditions Note 1 Note 2 Note 3
0.2 15 50 20 10.3 11.5 122
0.6 30 60
0.4 135 35 10.2 11.5 94 116
VCM = 10 V VS = 4.5 V to 18 V RL 2 k, VO = 10 V RL 2 k
108
2 16
4
51
AVO VO
600 11.5
1200 13.5
300 10.5
800 13.0
Electrical Characteristics < +85 C for OP37GP/GS/GZ, unless otherwise noted.)
Parameter Input Offset Voltage Average Input Offset Drift Input Offset Current Input Bias Current Input Voltage Range Common Mode Rejection Ratio Power Supply Rejection Ratio Large-Signal Voltage Gain Output Voltage Swing Symbol VOS TCVOS TCVOSN IOS IB IVR CMRR PSRR VCM = 10 V VS = 4.5 V to 18 V RL 2 k, VO = 10 V RL 2 k 750 Note 2 Note 3 Conditions Min OP37E Typ 20 Max 50 Min
(VS =
15 V, -25 C < TA < +85 C for OP37EZ/FZ, 0 C < TA < 70 C for OP37EP/FP, and -40 C < TA
OP37F Typ Max 40 140 OP37C Typ Max 55 220
Min
Unit V V/C nA nA V dB V/ V V/mV V
0.2 10 14 10.5 11.8 108 122
0.6 50 60
0.3 14 18 10.5 11.8 100 119
1.3 85 95
0.4 20 25 10.5 11.8 94 116
1.8 135 150
2
15
2
16
4
32
AVO VO
1500
700
1300
450 11
1000 13.3
11.7 13.6
11.4 13.5
NOTES 1 Input offset voltage measurements are performed by automated test equipment approximately 0.5 seconds after application of power. A/E grades guaranteed fully warmed up. 2 The TC VOS performance is within the specifications unnulled or when nulled withRP = 8 k to 20 k. TC VOS is 100% tested for A/E grades, sample tested for F/G grades. 3 Guaranteed by design.
-4-
REV. A
OP37
1. 2. 3. 4. 6. 7. 8. NULL (-) INPUT (+) INPUT V- OUTPUT V+ NULL
Wafer Test Limits
Parameter Input Offset Voltage Input Offset Current Input Bias Current Input Voltage Range Common Mode Rejection Ratio Power Supply Rejection Ratio Symbol VOS IOS IB IVR CMRR
(VS = 15 V, TA = 25 C for OP37N, OP37G, and OP37GR devices; TA = 125 C for OP37NT and OP37GT devices, unless otherwise noted.)
Conditions Note 1 OP37NT Limit 60 50 60 10.3 VCM = 11 V 108 OP37N Limit 35 35 40 11 114 OP37GT Limit 200 85 95 10.3 100 OP37G Limit 60 50 55 11 106 OP37GR Limit 100 75 80 11 100 Unit V MAX nA MAX nA MAX V MIN dB MIN
PSRR
TA = 25C, VS = 4 V to 18 V 10 TA = 125C, VS = 4.5 V to 18 V 16 RL 2 k, VO = 10 V RL 1 k, VO = 10 V RL 2 k RL 600 k VO = 0 600
10
10
10
20
V/V MAX V/V MAX
20
Large-Signal Voltage Gain
AVO
1000 800
500
1000 800
700
V/mV MIN V/mV MIN
Output Voltage Swing Power Consumption
VO Pd
11.5
12 10 140
11
12 10 140
11.5 10 170
V MIN V MIN mW MAX
NOTES For 25C 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 assembly and testing.
REV. A
-5-
OP37 Typical Electrical Characteristics (V =
S
15 V, TA = 25 C, unless otherwise noted.)
OP37N Typical OP37GT Typical OP37G Typical OP37GR Typical Unit
Parameter Average Input Offset Voltage Drift
Symbol
Conditions
OP37NT Typical
TCVOS or Nulled or Unnulled TCVOSN RP = 8 k to 20 k TCIOS TCIB en fO = 10 Hz fO = 30 Hz fO = 1000 Hz fO = 10 Hz fO = 30 Hz fO = 1000 Hz 0.1 Hz to 10 Hz RL 2k fO = 10 kHz
0.2 80 100 3.5 3.1 3.0 1.7 1.0 0.4 0.08 17 63
0.2 80 100 3.5 3.1 3.0 1.7 1.0 0.4 0.08 17 63
0.3 130 160 3.5 3.1 3.0 1.7 1.0 0.4 0.08 17 63
0.3 130 160 3.5 3.1 3.0 1.7 1.0 0.4 0.08 17 63
0.4 180 200 3.8 3.3 3.2 1.7 1.0 0.4 0.09 17 63
V/C pA/C pA/C nV/Hz nV/Hz nV/Hz pA/ Hz pA/ Hz pA/ Hz V p-p V/s MHz
Average Input Offset Current Drift Average Input Bias Current Drift Input Noise Voltage Density
Input Noise Current Density in Input Noise Voltage
en p-p
Slew Rate SR Gain Bandwidth Product GBW
-6-
REV. A
Typical Performance Characteristics- OP37
100 90 80
GAIN - dB
VOLTAGE NOISE - nV/ Hz
5 4 3 I/F CORNER = 2.7Hz
70 60 50 40 30 0.01 TEST TIME OF 10sec MUST BE USED TO LIMIT LOW FREQUENCY (<0.1Hz) GAIN.
VOLTAGE NOISE - nV/ Hz
10 9 8 7 6
100
TA = 25 C VS = 15V
741
2
I/F CORNER 10 I/F CORNER = LOW NOISE 2.7Hz AUDIO OP AMP OP37 I/F CORNER INSTRUMENTATION AUDIO RANGE RANGE TO DC TO 20kHz
1
0.1 1 10 FREQUENCY - Hz 100
1
1 10 100 FREQUENCY - Hz 1k
1
10 100 FREQUENCY - Hz
1k
TPC 1. Noise-Tester Frequency Response (0.1 Hz to 10 Hz)
TPC 2. Voltage Noise Density vs. Frequency
TPC 3. A Comparison of Op Amp Voltage Noise Spectra
10 TA = 25 C VS = 15V
100 TA = 25 C VS = 15V R1 R2
5 VS = 15V
V
VOLTAGE NOISE - nV/ Hz
TOTAL NOISE - nV/ Hz
RMS VOLTAGE NOISE -
RS - 2R1
4 AT 10Hz
1
10
3 AT 1kHz
0.1
AT 10Hz AT 1kHz RESISTOR NOISE ONLY
2
0.01 100
1k 10k BANDWIDTH - Hz
100k
1 100
1k SOURCE RESISTANCE -
10k
1 -50
-25
0 25 50 75 TEMPERATURE - C
100
125
TPC 4. Input Wideband Voltage Noise vs. Bandwidth (0.1 Hz to Frequency Indicated)
TPC 5. Total Noise vs. Source Resistance
TPC 6. Voltage Noise Density vs. Temperature
5
TA = 25 C
10.0
5.0
CURRENT NOISE - pA/ Hz
VOLTAGE NOISE - nV/ Hz
4 AT 10Hz AT 1kHz 3
SUPPLY CURRENT - mA
4.0 TA = +125 C 3.0 TA = -55 C 2.0 TA = +25 C
1.0
2
I/F CORNER = 140Hz 1 0.1 10
0
10
20
30
40
1.0
100 1k FREQUENCY - Hz 10k
5
TOTAL SUPPLY VOLTAGE (V+ - V-) - Volts
15 25 35 TOTAL SUPPLY VOLTAGE - Volts
45
TPC 7. Voltage Noise Density vs. Supply Voltage
TPC 8. Current Noise Density vs. Frequency
TPC 9. Supply Current vs. Supply Voltage
REV. A
-7-
OP37
CHANGE IN INPUT OFFSET VOLTAGE - V
40
OFFSET VOLTAGE - V
OP37B OP37A OP37B OP37A OP37A OP37B
CHANGE IN OFFSET VOLTAGE - V
60 50 30 20 10 0 -10 -20 -30 -40
OP37C
6 4 2 0 -2 -4 -6 6 4 2 0 -2 -4 -6 0 1 2 3 4 5 6 7 TIME - MONTHS
TA = 25 C VS = 15V 10 OP37C/G OP37F 5 OP37A/E
TRIMMING WITH -50 10k POT DOES NOT CHANGE -60 TCV OS OP37C -70 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE - C
1
0
1
2
3
4
5
TIME AFTER POWER ON - MINUTES
TPC 10. Offset Voltage Drift of Eight Representative Units vs. Temperature
TPC 11. Long-Term Offset Voltage Drift of Six Representative Units
TPC 12. Warm Up Offset Voltage Drift
30 VS = +15V
INPUT BIAS CURRENT - nA
50 VS = +15V
INPUT OFFSET CURRENT - nA
50 VS = 40 15V
25
OPEN-LOOP GAIN - dB
20
TA = 25 C
TA = 70 C THERMAL SHOCK RESPONSE BAND
40
30 OP37C 20
30
15
20 OP37C 10 OP37B OP37A 0 -75 -50 -25 0 25 50 75 TEMPERATURE - C 100 125
10 DEVICE IMMERSED IN 70 C OIL BATH
5
10
OP37B OP37A
0 -20
0
20
40
60
80
100
0 -50 -25 0 25 50 75 100 125 150 TEMPERATURE - C
TIME - Seconds
TPC 13. Offset Voltage Change Due to Thermal Shock
140 TA = 25 C VS = 15V RL 2k
TPC 14. Input Bias Current vs. Temperature
TPC 15. Input Offset Current vs. Temperature
60 -80 TA = 25 C VS = 15V -100 -120 PHASE MARGIN = 71 AV = 5 10 0 -10 100k -180 -200 -220 100M -140 -160
PHASE MARGIN - DEG
80 75 70 65 60 55 30 25 20 15 10 -50 -25 0 25 50 75 100 SLEW GBW VS = M 15V
90
GAIN-BANDWIDTH PRODUCT - MHz F = 10kHz
OPEN-LOOP VOLTAGE GAIN - dB
120 100 80 60 40 20 0
85 80 75 70 65 60 55 50 45 40 125
50 40
30 20
1
10
102
103 104 105 106 FREQUENCY - Hz
107
108
SLEW RATE - V/ s
TEMPERATURE - C
1M 10M FREQUENCY - Hz
TPC 16. Open-Loop Gain vs. Frequency
TPC 17. Slew Rate, Gain Bandwidth Product, Phase Margin vs. Temperature
TPC 18. Gain, Phase Shift vs. Frequency
-8-
REV. A
PHASE SHIFT - Degrees
GAIN - dB
OP37
2.5 TA = 25 C
PEAK-TO-PEAK AMPLITUDE - Volts
28 24 20 16 12 8 4 0 104 TA = 25 C VS = 15V MAXIMUM OUTPUT - Volts
18 16 14 12 10 8 6 4 2 0 105 106 FREQUENCY - Hz 107 -2 100 TA = 25 C VS = 15V 1k LOAD RESISTANCE - 10k NEGATIVE SWING POSITIVE SWING
OPEN-LOOP GAIN - V/ V
2.0 RL = 2k 1.5 RL = 1k 1.0
0.5
0
0
10
20
30
40
50
TOTAL SUPPLY VOLTAGE - Volts
TPC 19. Open-Loop Voltage Gain vs. Supply Voltage
TPC 20. Maximum Output Swing vs. Frequency
TPC 21. Maximum Output Voltage vs. Load Resistance
80
5V PERCENT OVERSHOOT 1s +50mV 20mV 200ns
60
+10V
40
0V
0V TA = 25 C VS = 15V AV = +5 (1k , 250 )
20
VS = 15V VIN = 20mV AV = +5 (1k , 250 ) 0 500 1000 1500 2000
-10V
TA = 25 C VS = 15V AV = +5 (1k , 250 )
-50mV
0
CAPACITIVE LOAD - pF
TPC 22. Small-Signal Overshoot vs. Capacitive Load
TPC 23. Large-Signal Transient Response
TPC 24. Small-Signal Transient Response
60
SHORT-CIRCUIT CURRENT - mA
140
COMMON-MODE RANGE - Volts
16
VS = 15V TA = 25 C VCM = 10V
TA = 25 C VS = 15V 50
12 TA = +25 C 8
TA = -55 C
120
TA = +125 C 4 0 TA = -55 C -4 TA = +25 C -8 -12 -16 TA = +125 C
40
ISC(+)
CMRR - dB
100
30 ISC(-) 20
80
60
10
0
1
2
3
4
5
40 1k
10k
TIME FROM OUTPUT SHORTED TO GROUND - MINUTES
100k 1M FREQUENCY - Hz
10M
0
5
10
15
20
SUPPLY VOLTAGE - Volts
TPC 25. Short-Circuit Current vs. Time
TPC 26. CMRR vs. Frequency
TPC 27. Common-Mode Input Range vs. Supply Voltage
REV. A
-9-
OP37
0.1 F 100k
2.4
OPEN-LOOP VOLTAGE GAIN - V/ V
1 SEC/DIV
2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6
TA = 25 C VS = 15V
10
OP37 D.U.T.
2k
VOLTAGE GAIN = 50,000
4.3k OP12 100k 2.2 F 0.1 F
24.3k
22 F
SCOPE 1 RIN = 1M
4.7 F
110k
0.4 100
1k 10k LOAD RESISTANCE -
100k
TPC 28. Noise Test Circuit (0.1 Hz to 10 Hz)
TPC 29. Low-Frequency Noise
TPC 30. Open-Loop Voltage Gain vs. Load Resistance
160
POWER SUPPLY REJECTION RATIO - dB
19
TA = 25 C
20
140 120
VOLTAGE NOISE - V/ s
18
SLEW RATE - V/ V
TA = 25 C VS = 15V AV = 5 VO = 20V p-p
TA = 25 C AVCL = 5 15
RISE
100 80 60 40 20 0 POSITIVE SWING NEGATIVE SWING
FALL
17
10
16
5
1
10
100
1k 10k 100k 1M 10M 100M FREQUENCY - Hz
15 100
0
1k 10k LOAD RESISTANCE -
100k
3
6
9 12 15 18 SUPPLY VOLTAGE - Volts
21
TPC 31. PSRP vs. Frequency
TPC 32. Slew Rate vs. Load
TPC 33. Slew Rate vs. Supply Voltage
-10-
REV. A
OP37
APPLICATIONS INFORMATION Noise Measurements
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 offset nulling circuit). 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 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 maintained at the same temperature.
10k RP V+
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: * The device has to be warmed-up forat least five minutes. As shown in the warm-up drift curve, the offset voltage typically changes 4 V due to increasing chip temperature after power up. In the ten second measurement interval, these temperatureinduced effects can exceed tens of nanovolts. * For similar reasons, the device has to be well-shielded from air currents. Shielding minimizes thermocouple effects. * Sudden motion in the vicinity of the device can also "feedthrough" to increase the observed noise. * 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. * 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
-
OP37
+
OUTPUT
V-
Figure 1. Offset Nulling Circuit
Offset Voltage Adjustment
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
INPUT (-)
1
4.7k
1k
POT
4.7k
8
V+
R3 390 R2 100 R4 5k 0.1% C1 100pF R6 500 0.1%
Figure 2. TBD
+18V
INPUT (+)
OP37 +
OP37
-18V
Figure 3. Burn-In Circuit
REV. A
-11-
-
+
The input offset voltage of the OP37 is trimmed at wafer level. However, if further adjustment of VOS is necessary, a 10 k trim potentiometer may be used. TCVOS is not degraded (see offset nulling circuit). Other potentiometer values from 1 k to 1 M can be used with a slight degradation (0.1 V/C to 0.2 V/C) of TCVOS. Trimming to a value other than zero creates a drift of approximately (VOS/300) V/C. For example, the change in TCVOS will be 0.33 V/C if VOS is adjusted to 100 V. The offset voltage adjustment range with a 10 k 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 below will have a 280 V adjustment range.
A three-op-amp instrumentation amplifier 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's ac commonmode rejection.
R5 500 0.1% R1 5k 0.1% R7 100k R8 20k 0.1%
OP37
- OP37 +
VOUT
-
R9 19.8k R10 500
NOTES: TRIM R2 FOR AVCL = 1000 TRIM R10 FOR dc CMRR TRIM R7 FOR MINIMUM V OUT AT V CM = 20V p-p, 10kHz
Figure 4a. TBD
OP37
140 RS = 0 120 TA = 25 C VS = 15V VCM = 20V p-p AC TRIM @ 10kHz RS = 0
1k OP08/108 500 5534
OP07 p-p NOISE - nV
CMRR - dB
100
RS = 1k BALANCED RS = 100 , UNBALANCED
1 100 OP27/37 50 2
80 1k 60
1 RS e.g. RS 2 RS e.g. RS
UNMATCHED = R S1 = 10k , R S2 = 0 MATCHED = 10k , R S1 = R S2 = 5k RS1
40 10 100 1k 10k FREQUENCY - Hz 100k 1M
REGISTER NOISE ONLY 10 50 100
RS2
10k 500 1k 5k RS - SOURCE RESISTANCE -
50k
Figure 4b. TBD
Comments on Noise
Figure 6. Peak-to-Peak Noise (0.1 Hz to 10 Hz) vs. Source Resistance (Includes Resistor 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 IB and IOS of only 40 nA and 35 nA respectively at 25C. 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 IB. TCVOS of previous designs have made direct coupling difficult, if not impossible, to use.
100
At RS < 1 k key the OP37's low voltage noise is maintained. With RS < 1 k, total noise increases, but is dominated by the resistor noise rather than current or voltage noise. It is only beyond Rs of 20kil 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 to 40 k region.
100
50
1 2 OP08/108
50 1
TOTAL NOISE - nV/ Hz
TOTAL NOISE - nV/ Hz
10
OP07 5534
OP08/108 2 OP07 10
1 RS e.g. RS 2 RS e.g. RS UNMATCHED = R S1 = 10k , R S2 = 0 MATCHED = 10k , R S1 = R S2 = 5k RS1
5 OP27/37
1 RS e.g. RS 2 RS e.g. RS
UNMATCHED = R S1 = 10k , R S2 = 0 MATCHED = 10k , R S1 = R S2 = 5k RS1
5
5534 OP27/37 REGISTER NOISE ONLY
REGISTER NOISE ONLY 1 50 100
RS2
RS2
10k 500 1k 5k RS - SOURCE RESISTANCE -
50k
1 50
100
500 1k 5k 10k RS - SOURCE RESISTANCE -
50k
Figure 7. !0 Hz Noise vs. Source resistance (Inlcludes Resistor Noise)
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's 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 (resistor noise_]1/2 RS)2 +
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 OP-07 occurs in the 3 k to 5 k range depending on whether balanced or unbalanced source resistors are used (at 3 k the IB. IOS error also can be three times the VOS spec.). Therefore, for low-frequency applications, the OP07 is better than the OP27/37 when Rs > 3 k. The only exception is when gain error is important. Figure 3 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.
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.
-12-
REV. A
OP37
Table I. TBD
Device Straln Gauge Magnetic Tapehead
Source Impedance <500 <1500
Comments Typically used in low-frequency applications. Low IB very important to reduce set-magnetization problems when direct coupling is used. OP37 IB can be neglected. Similar need for low IB in direct coupled applications. OP47 will not introduce any self-magnetization problem. Used in rugged servo-feedback applications. Bandwidth of interest is 400 Hz to 5 kHz.
by only 0.7 dB. With a 1 k 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:
R G = 0.101 1 + 1 R3
Magnetic Phonograph Cartridges
<1500
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 R4form a simple -6 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's 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 4 can be readily modified for tape use, as shown by Figure 5.
-
0.47 F
Linear Variable <1500 Differential Transformer
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.
C4 (2) 220 F + + MOVING MAGNET CARTRIDGE INPUT Ca 150pF LF ROLLOFF OUT R5 100k
Ra 47.5k
A1 OP27
C3 0.47 F
IN
R1 97.6k R2 7.87k R3 100
R4 75k C1 0.03 F C2 0.01 F
OUTPUT
TAPE HEAD
Ra
Ca
OP37 +
R1 33k
15k
G = 1kHz GAIN R1 = 0.101 ( 1 + ) R3 = 98.677 (39.9dB) AS SHOWN
R2 5k 100k
0.01 F
T1 = 3180 s T2 = 50 s
Figure 8. TBD
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 network with standard component values. The popular method to accomplish RIAA phono equalization is to employ frequencydependent feedback around a high-quality gain block. Properly chosen, an RC network can provide the three necessary time constants of 3180 s, 318 s, and 75 s.1 For initial equalization accuracy and stability, precision metalfilm 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--can be considered for small values or where space is at a premium.) The OP27 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 , which generates a voltage noise of 1.3 nV/Hz. The noise increases the 3.2 nV/Hz of the amplifier
Figure 9. TBD
While the tape-equalization requirement has a flat high frequency gain above 3 kHz (t2 = 50 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 performance 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 output offset is just over 500 mV. A single 0.47 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 in. head (such as the PRB2H7K) will not be troublesome. One potential tape-head problem is presented by amplifier biascurrent transients which can magnetize a head. The OP27 and
REV. A
-13-
OP37
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. 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 impedance microphones by 50 dB, and has an input impedance of 2 k. 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, RP, may be necessary, if the microphone is to be unplugged. Otherwise the 100% feedback from the open input may cause the amplifier to oscillate.
R1 1k R3 316k C1 5F R6 100
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.
C2 1800pF R1 121 R2 1100
T1* 150 SOURCE R3 100
A1 OP27
OUTPUT
* T1 - JENSEN JE - 115K - E JENSEN TRANSFORMERS 10735 BURBANK BLVD. N. HOLLYWOOD, CA 91601
Figure 11. TBD
LOW IMPEDANCE MICROPHONE INPUT (Z = 50 TO 200 ) R2 1k
-
Rp 30k
OP37 +
R4 316k
R7 10k
OUTPUT
Capacitor C2 and resistor R2 form a 2 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 s time constant 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 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 -69.5 referenced to 1 mV).
References 1. Lipshitz, S.P, "On 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 Company, 1978. 4. Jung, W.G., and Marsh, R.M., "Picking Capacitors." Audio, February & March, 1980. 5. Otala, M., "Feedback-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.
R3 = R4 R1 R2
Figure 10. TBD
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 nVHz noise, while the op amp generates a 3.2 nVHz noise. The rms sum of these predominant noise sources will be about 6 nVHz, equivalent to 0.9 V in a 20 kHz noise bandwidth, 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 /15 k 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's voltage setup and the op amp's 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
-14-
REV. A
OP37
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead Hermetic DIP (Z Suffix)
0.005 (0.13) MIN
8
0.055 (1.4) MAX
5
PIN 1
1 4
0.310 (7.87) 0.220 (5.59)
0.100 (2.54) BSC 0.405 (10.29) MAX 0.200 (5.08) MAX 0.200 (5.08) 0.125 (3.18) 0.060 (1.52) 0.015 (0.38) 0.150 (3.81) MIN 15 0 0.015 (0.38) 0.008 (0.20) 0.320 (8.13) 0.290 (7.37)
SEATING 0.023 (0.58) 0.070 (1.78) PLANE 0.014 (0.36) 0.030 (0.76)
Epoxy Mini-Dip (P Suffix)
0.430 (10.92) 0.348 (8.84)
8 5
0.280 (7.11) 0.240 (6.10)
1 4
PIN 1
0.100 (2.54) BSC
0.325 (8.25) 0.300 (7.62) 0.060 (1.52) 0.015 (0.38) 0.130 (3.30) MIN 0.015 (0.381) 0.008 (0.204) 0.195 (4.95) 0.115 (2.93)
0.210 (5.33) MAX 0.160 (4.06) 0.115 (2.93)
0.022 (0.558) 0.070 (1.77) SEATING 0.014 (0.356) 0.045 (1.15) PLANE
8-Lead SO (S Suffix)
0.1968 (5.00) 0.1890 (4.80)
8 5 4
0.1574 (4.00) 0.1497 (3.80) PIN 1
1
0.2440 (6.20) 0.2284 (5.80)
0.0500 (1.27) BSC 0.0098 (0.25) 0.0040 (0.10) SEATING PLANE 0.0688 (1.75) 0.0532 (1.35) 0.0192 (0.49) 0.0138 (0.35) 8 0.0098 (0.25) 0 0.0075 (0.19)
0.0196 (0.50) 0.0099 (0.25)
45
0.0500 (1.27) 0.0160 (0.41)
REV. A
-15-
OP37 Revision History
Location Data Sheet changed from REV. B to REV. C. Page
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
C00319-0-2/02(A) PRINTED IN U.S.A.
-16-
REV. A

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