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.
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
1
8
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/
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 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. Over
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
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.
REV. A
OP37
2
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 . . . . . . . . . . . . . 65
C to +150C
Operating Temperature Range
OP37A . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
C to +1 25C
OP37E (Z) . . . . . . . . . . . . . . . . . . . . . . . . . . 25
C to +85C
OP37E, OP-37F (P) . . . . . . . . . . . . . . . . . . . . . 0
C to 70C
OP37G (P, S, Z) . . . . . . . . . . . . . . . . . . . . . 40
C to +85C
Lead Temperature Range (Soldering, 60 sec) . . . . . . . . 300
C
Junction Temperature . . . . . . . . . . . . . . . . . . 45
C to +150C
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'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.
ORDERING GUIDE
T
A
= 25
C
Operating
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. A
3
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
V
Long-Term
Stability
V
OS
/Time
Notes 2, 3
0.2
1.0
0.3
1.5
0.4
2.0
V/Mo
Input Offset
Current
I
OS
7
35
9
50
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
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
CurrentDensity
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
Input Resistance
Common Mode
R
INCM
3
2.5
2
G
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
V/ V
to
18 V
Large Signal
Voltage Gain
A
VO
R
L
2 k,
V
O
=
10 V
1000
1800
1000
1800
700
1500
V/m V
R
L
1 k,
Vo =
10 V
800
1500
800
1500
400
1500
V/m V
R
L
600 ,
V
O
=
1 V,
V
S
4
4
250
700
250
700
200
500
V/m V
Output Voltage
Swing
V
O
R
L
2 k
12.0 13.8
12.0 13.8
11.5 13.5
V
R
L
600
10
11.5
10
11.5
10
11.5
V
Slew Rate
SR
R
L
2k
4
11
17
11
17
11
17
V/
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
Power
Consumption
P
d
V
O
= 0
90
140
90
140
100
170
mW
Offset Adjustment
Range
R
P
= 10 k
4
4
4
mV
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
4
OP37SPECIFICATIONS
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
V
Average Input
Offset Drift
TCV
OS
Note 2
TCV
OSN
Note 3
0.2
0.6
0.4
1.8
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
V/ V
Large-Signal
Voltage Gain
A
VO
R
L
2 k,
V
O
=
10 V
600
1200
300
800
V/m V
Output Voltage
Swing
V
O
R
L
2 k
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
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
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
V/ V
Large-Signal
Voltage Gain
A
VO
R
L
2 k,
VO
=
10 V
750
1500
700
1300
450
1000
V/mV
Output Voltage
Swing
V
O
R
L
2 k
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 power. A/E grades guaranteed fully
warmed up.
2
The TC
VOS
performance is within the specifications unnulled or when nulled withR
P
= 8 k
to 20 k. TC
VOS
is 100% tested for A/E grades, sample tested for F/G grades.
3
Guaranteed by design.
( V
S
= 15 V, 55 C < T
A
< +125 C, unless otherwise noted.)
(V
S
= 15 V, 25 C < T
A
< +85 C for OP37EZ/FZ, 0 C < T
A
< 70 C for OP37EP/FP, and 40 C < T
A
< +85 C for OP37GP/GS/GZ, unless otherwise noted.)
REV. A
OP37
5
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
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
10
10
20
V/V MAX
T
A
= 125
C,
V
S
=
4.5 V to
18 V
16
20
V/V MAX
Large-Signal
Voltage Gain
A
VO
R
L
2 k,
V
O
=
10 V
600
1000
500
1000
700
V/mV MIN
R
L
1 k,
V
O
=
10 V
800
800
V/mV MIN
Output Voltage
Swing
V
O
R
L
2 k
11.5
12
11
12
11.5
V MIN
R
L
600 k
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 assembly and testing.
1. NULL
2. () INPUT
3. (+) INPUT
4. V
6. OUTPUT
7. V+
8. NULL
(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.)
REV. A
OP37
6
Typical 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
to 20 k
0.2
0.2
0.3
0.3
0.4
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
V p-p
Slew Rate
SR
R
L
2k
17
17
17
17
17
V/
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. A
7
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)
BANDWIDTH Hz
RMS V
O
L
T
A
GE
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)
TOTAL SUPPLY VOLTAGE (V+ V) Volts
V
O
L
T
A
GE NOISE
nV/ Hz
5
4
1
0
10
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
V
O
L
T
A
GE NOISE
nV/ Hz
I/F CORNER = 2.7Hz
TPC 2. Voltage Noise Density vs.
Frequency
SOURCE RESISTANCE
100
1
10k
100
1k
T
O
T
A
L NOISE
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
V
O
L
T
A
GE NOISE
nV/ Hz
10
LOW NOISE
AUDIO OP AMP
INSTRUMENTATION
RANGE TO DC
AUDIO 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
V
O
L
T
A
GE NOISE
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
TOTAL SUPPLY VOLTAGE Volts
SUPPL
Y 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
Typical Performance Characteristics
REV. A
OP37
8
TEMPERATURE C
OFFSET V
O
L
T
A
GE
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
0
20
40
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
V
O
L
T
A
GE 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
V
O
L
T
A
GE
V
6
0
2
2
6
4
0
2
6
1
2
3
4
5
6
7
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 RA
TE
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-B
AND
WIDTH PR
ODUCT
MHz
F = 10kHz
GBW
TPC 17. Slew Rate, Gain Bandwidth
Product, Phase Margin vs. Temperature
TIME AFTER POWER ON MINUTES
CHANGE IN INPUT OFFSET
V
O
L
T
A
GE
V
10
1
0
1
4
2
3
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. A
9
OP37
TOTAL SUPPLY VOLTAGE Volts
OPEN-LOOP GAIN
V/
V
2.5
0
10
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 O
VERSHOO
T
80
60
0
0
500
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
SHOR
T
-
CIRCUIT CURRENT
mA
60
0
1
4
2
3
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-T
O
-PEAK AMPLITUDE
V
o
lts
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
10V
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
V
o
lts
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
50mV
T
A
= 25 C
V
S
= 15V
A
V
= +5
(1k , 250 )
TPC 24. Small-Signal Transient
Response
SUPPLY VOLTAGE Volts
COMMON-MODE RANGE
V
o
lts
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. A
OP37
10
OP12
OP37
D.U.T.
100k
4.3k
4.7 F
2k
24.3k
VOLTAGE
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
PO
WER SUPPL
Y REJECTION RA
TIO
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. PSRP vs. Frequency
1 SEC/DIV
TPC 29. Low-Frequency Noise
LOAD RESISTANCE
19
100
1k
10k
100k
SLEW RA
TE
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 V
O
L
T
A
GE
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
V
O
L
T
A
GE NOISE
V/
s
20
3
15
10
5
0
T
A
= 25 C
A
VCL
= 5
6
9
12
15
18
21
FALL
RISE
TPC 33. Slew Rate vs. Supply Voltage
REV. A
OP37
11
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 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 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
trim
potentiometer may be used. TCV
OS
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
TCV
OS
. Trimming to a value other than zero creates a drift of
approximately (V
OS
/300)
V/C. For example, the change in TCV
OS
will be 0.33
V/C if V
OS
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.
1
8
4.7k
4.7k
1k
POT
V+
Figure 2. TBD
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:
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 temperature-
induced 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
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 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 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. TBD
REV. A
OP37
12
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
BALANCED
R
S
= 0
Figure 4b. TBD
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
T
O
T
A
L NOISE
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'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 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
key the OP37's low voltage noise is maintained.
With R
S
< 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.
R
S
SOURCE RESISTANCE
10
50
10k
T
O
T
A
L NOISE
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. !0 Hz Noise vs. Source resistance (Inlcludes
Resistor Noise)
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 bal-
anced or unbalanced source resistors are used (at 3 k
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
. 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.
REV. A
OP37
13
Table I. TBD
Source
Device
Impedance
Comments
Straln Gauge
<500
Typically used in low-frequency
applications.
Magnetic
<1500
Low I
B
very important to reduce
Tapehead
set-magnetization problems when
direct coupling is used. OP37
I
B
can be neglected.
Magnetic
<1500
Similar need for low I
B
in direct
Phonograph
coupled applications. OP47 will not
Cartridges
introduce any self-magnetization
problem.
Linear Variable <1500
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. 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 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
s, 318 s, and 75 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--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
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:
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 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.
Ca
Ra
R1
33k
TAPE
HEAD
0.47 F
0.01 F
R2
5k
100k
15k
T1 = 3180 s
T2 = 50 s
OP37
+
Figure 9. TBD
While the tape-equalization requirement has a flat high frequency
gain above 3 kHz (t
2
= 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 R
A
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
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 bias-
current transients which can magnetize a head. The OP27 and
REV. A
OP37
14
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 imped-
ance 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, 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. 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 nV
Hz noise, while the op amp generates a 3.2 nVHz
noise. The rms sum of these predominant noise sources will be
about 6 nV
Hz, 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
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. TBD
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 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
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 Com-
pany, 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.
REV. A
OP37
15
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead Hermetic DIP
(Z Suffix)
1
4
8
5
0.310 (7.87)
0.220 (5.59)
PIN 1
0.005 (0.13)
MIN
0.055 (1.4)
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)
Epoxy Mini-Dip
(P Suffix)
SEATING
PLANE
0.060 (1.52)
0.015 (0.38)
0.210
(5.33)
MAX
0.022 (0.558)
0.014 (0.356)
0.160 (4.06)
0.115 (2.93)
0.070 (1.77)
0.045 (1.15)
0.130
(3.30)
MIN
8
1
4
5
PIN 1
0.280 (7.11)
0.240 (6.10)
0.100 (2.54)
BSC
0.430 (10.92)
0.348 (8.84)
0.195 (4.95)
0.115 (2.93)
0.015 (0.381)
0.008 (0.204)
0.325 (8.25)
0.300 (7.62)
8-Lead SO
(S Suffix)
0.0098 (0.25)
0.0075 (0.19)
0.0500 (1.27)
0.0160 (0.41)
8
0
0.0196 (0.50)
0.0099 (0.25)
45
8
5
4
1
0.1968 (5.00)
0.1890 (4.80)
0.2440 (6.20)
0.2284 (5.80)
PIN 1
0.1574 (4.00)
0.1497 (3.80)
0.0500 (1.27)
BSC
0.0688 (1.75)
0.0532 (1.35)
SEATING
PLANE
0.0098 (0.25)
0.0040 (0.10)
0.0192 (0.49)
0.0138 (0.35)
REV. A
16
C0031902/02(A)
PRINTED IN U.S.A.
Revision History
Location
Page
Data Sheet changed from REV. B to REV. C.
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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