Precision Low Noise, Low Input
Bias Current Operational Amplifiers
OP1177/OP2177/OP4177
Rev. D
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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. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
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One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 www.analog.com
Fax: 781.461.3113 ©2006 Analog Devices, Inc. All rights reserved.
FEATURES
Low offset voltage: 60 μV maximum
Very low offset voltage drift: 0.7 μV/°C maximum
Low input bias current: 2 nA maximum
Low noise: 8 nV/√Hz typical
CMRR, PSRR, and AVO > 120 dB minimum
Low supply current: 400 μA per amplifier
Dual supply operation: ±2.5 V to ±15 V
Unity gain stable
No phase reversal
Inputs internally protected beyond supply voltage
APPLICATIONS
Wireless base station control circuits
Optical network control circuits
Instrumentation
Sensors and controls
Thermocouples
Resistor thermal detectors (RTDs)
Strain bridges
Shunt current measurements
Precision filters
PIN CONFIGURATIONS
–IN
+IN
V–
V+
NC
NC
18
OP1177
NC
OUT
NC = NO CONNECT
45
02627-001
1
2
3
4
8
7
6
5
IN
V–
+IN
V+
OUT
NC
NC
NC
NC = NO CONNECT
OP1177
02627-002
Figure 1. 8-Lead MSOP (RM-Suffix) Figure 2. 8-Lead SOIC_N (R-Suffix)
–IN A
+IN A
V–
OUT B
+IN B
V+
18
OP2177
OUT A
–IN B
45
02627-003
1
2
3
4
8
7
6
5
–IN A
V–
+IN A
OUT B
–IN B
V+
+IN B
OUT A
OP2177
02627-004
Figure 3. 8-Lead MSOP (RM-Suffix) Figure 4. 8-Lead SOIC_N (R-Suffix)
OUT B 78
+IN B 510
–IN B 69
V+ 411
–IN A 213
+IN A 312
OUT A 114
OUT C
+IN C
–IN C
V–
–IN D
+IN D
OUT D
OP4177
02627-005
OUT A
–IN A
+IN A
V+
+IN B
–IN B
OUT B
–IN D
+IN D
V–
OUT D
–IN C
OUT C
+IN C
14
8
1
7
OP4177
02627-006
Figure 5. 14-Lead SOIC_N (R-Suffix) Figure 6. 14-Lead TSSOP (RU-Suffix)
GENERAL DESCRIPTION
The OPx177 family consists of very high precision, single, dual,
and quad amplifiers featuring extremely low offset voltage and
drift, low input bias current, low noise, and low power
consumption. Outputs are stable with capacitive loads of over
1000 pF with no external compensation. Supply current is less
than 500 A per amplifier at 30 V. Internal 500  series resistors
protect the inputs, allowing input signal levels several volts
beyond either supply without phase reversal.
Unlike previous high voltage amplifiers with very low offset
voltages, the OP1177 and OP2177 are available in a tiny
MSOP 8-lead surface-mount package, and the OP4177 is
available in a 14-lead TSSOP. Moreover, specified
performance in the MSOP and the TSSOP is identical to
performance in the SOIC package.
The OPx177 family offers the widest specified temperature
range of any high precision amplifier in surface-mount
packaging. All versions are fully specified for operation from
−40°C to +125°C for the most demanding operating
environments.
Applications for these amplifiers include precision diode
power measurement, voltage and current level setting, and
level detection in optical and wireless transmission
systems. Additional applications include line-powered and
portable instrumentation and controls—thermocouple,
RTD, strain-bridge, and other sensor signal conditioning—
and precision filters.
The OP1177 (single) and the OP2177 (dual) amplifiers are
available in 8lead MSOP and 8lead narrow SOIC packages.
The OP4177 (quad) is available in 14lead TSSOP and 14lead
narrow SOIC packages. MSOP and TSSOP are available in tape
and reel only.
OP1177/OP2177/OP4177
Rev. D | Page 2 of 24
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
Pin Configurations ........................................................................... 1
General Description......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Electrical Characteristics ................................................................. 4
Absolute Maximum Ratings............................................................ 5
Thermal Resistance ...................................................................... 5
ESD Caution.................................................................................. 5
Typical Performance Characteristics ............................................. 6
Functional Description .................................................................. 14
Total Noise-Including Source Resistors................................... 14
Gain Linearity ............................................................................. 14
Input Overvoltage Protection ................................................... 15
Output Phase Reversal............................................................... 15
Settling Time............................................................................... 15
Overload Recovery Time .......................................................... 15
THD + Noise............................................................................... 16
Capacitive Load Drive ............................................................... 16
Stray Input Capacitance Compensation.................................. 17
Reducing Electromagnetic Interference.................................. 17
Proper Board Layout.................................................................. 18
Difference Amplifiers ................................................................ 18
A High Accuracy Thermocouple Amplifier........................... 19
Low Power Linearized RTD...................................................... 19
Single Operational Amplifier Bridge....................................... 20
Realization of Active Filters .......................................................... 21
Band-Pass KRC or Sallen-Key Filter........................................ 21
Channel Separation.................................................................... 21
References on Noise Dynamics and Flicker Noise ................ 21
Outline Dimensions ....................................................................... 22
Ordering Guide .......................................................................... 24
REVISION HISTORY
7/06—Rev. C to Rev. D
Changes to Table 4............................................................................ 5
Changes to Figure 51...................................................................... 14
Changes to Figure 52...................................................................... 15
Changes to Figure 54...................................................................... 16
Changes to Figure 58 to Figure 61................................................ 17
Changes to Figure 62 and Figure 63............................................. 18
Changes to Figure 64...................................................................... 19
Changes to Figure 65 and Figure 66............................................. 20
Changes to Figure 67 and Figure 68............................................. 21
Removed SPICE Model Section ................................................... 21
Updated Outline Dimensions....................................................... 22
Changes to Ordering Guide .......................................................... 24
4/04—Rev. B to Rev. C
Changes to Ordering Guide ............................................................ 4
Changes to TPC 6 ............................................................................. 5
Changes to TPC 26........................................................................... 7
Updated Outline Dimensions....................................................... 17
4/02—Rev. A to Rev. B
Added OP4177.........................................................................Global
Edits to Specifications.......................................................................2
Edits to Electrical Characteristics Headings..................................4
Edits to Ordering Guide ...................................................................4
11/01—Rev. 0 to Rev. A
Edit to Features ..................................................................................1
Edits to TPC 6 ...................................................................................5
7/01—Revision 0: Initial Version
OP1177/OP2177/OP4177
Rev. D | Page 3 of 24
SPECIFICATIONS
VS = ±5.0 V, VCM = 0 V, TA = 25°C, unless otherwise noted.
Table 1.
Parameter Symbol Conditions Min Typ1Max Unit
INPUT CHARACTERISTICS
Offset Voltage
OP1177 VOS 15 60 V
OP2177/OP4177 VOS 15 75 V
OP1177/OP2177 VOS −40°C < TA < +125°C 25 100 V
OP4177 VOS −40°C < TA < +125°C 25 120 V
Input Bias Current IB −40°C < TA < +125°C −2 +0.5 +2 nA
Input Offset Current IOS −40°C < TA < +125°C −1 +0.2 +1 nA
Input Voltage Range −3.5 +3.5 V
Common-Mode Rejection Ratio CMRR VCM = −3.5 V to +3.5 V 120 126 dB
−40°C < TA < +125°C 118 125 dB
Large Signal Voltage Gain AVO R
L = 2 kΩ, VO = –3.5 V to +3.5 V 1000 2000 V/mV
Offset Voltage Drift
OP1177/OP2177 ∆VOS/∆T −40°C < TA < +125°C 0.2 0.7 V/°C
OP4177 ∆VOS/∆T −40°C < TA < +125°C 0.3 0.9 V/°C
OUTPUT CHARACTERISTICS
Output Voltage High VOH I
L = 1 mA, −40°C < TA < +125°C +4 +4.1 V
Output Voltage Low VOL I
L = 1 mA, −40°C < TA < +125°C −4.1 −4 V
Output Current IOUT V
DROPOUT < 1.2 V ±10 mA
POWER SUPPLY
Power Supply Rejection Ratio
OP1177 PSRR VS = ±2.5 V to ±15 V 120 130 dB
−40°C < TA < +125°C 115 125 dB
OP2177/OP4177 PSRR VS = ±2.5 V to ±15 V 118 121 dB
−40°C < TA < +125°C 114 120 dB
Supply Current per Amplifier ISY V
O = 0 V 400 500 A
−40°C < TA < +125°C 500 600 A
DYNAMIC PERFORMANCE
Slew Rate SR RL = 2 kΩ 0.7 V/s
Gain Bandwidth Product GBP 1.3 MHz
NOISE PERFORMANCE
Voltage Noise en p-p 0.1 Hz to 10 Hz 0.4 V p-p
Voltage Noise Density en f = 1 kHz 7.9 8.5 nV/√Hz
Current Noise Density in f = 1 kHz 0.2 pA/√Hz
MULTIPLE AMPLIFIERS CHANNEL
SEPARATION CS DC 0.01 V/V
f = 100 kHz −120 dB
1 Typical values cover all parts within one standard deviation of the average value. Average values given in many competitor data sheets as “typical” give unrealistically
low estimates for parameters that can have both positive and negative values.
OP1177/OP2177/OP4177
Rev. D | Page 4 of 24
ELECTRICAL CHARACTERISTICS
VS = ±15 V, VCM = 0 V, TA = 25°C, unless otherwise noted.
Table 2.
Parameter Symbol Conditions Min Typ1Max Unit
INPUT CHARACTERISTICS
Offset Voltage
OP1177 VOS 15 60 V
OP2177/OP4177 VOS 15 75 V
OP1177/OP2177 VOS −40°C < TA < +125°C 25 100 V
OP4177 VOS −40°C < TA < +125°C 25 120 V
Input Bias Current IB −40°C < TA < +125°C −2 +0.5 +2 nA
Input Offset Current IOS −40°C < TA < +125°C −1 +0.2 +1 nA
Input Voltage Range −13.5 +13.5 V
Common-Mode Rejection Ratio CMRR VCM = −13.5 V to +13.5 V,
−40°C < TA < +125°C 120 125 dB
Large Signal Voltage Gain AVO R
L = 2 kΩ, VO = –13.5 V to +13.5 V 1000 3000 V/mV
Offset Voltage Drift
OP1177/OP2177 ∆VOS/∆T −40°C < TA < +125°C 0.2 0.7 V/°C
OP4177 ∆VOS/∆T −40°C < TA < +125°C 0.3 0.9 V/°C
OUTPUT CHARACTERISTICS
Output Voltage High VOH I
L = 1 mA, −40°C < TA < +125°C +14 +14.1 V
Output Voltage Low VOL I
L = 1 mA, −40°C < TA < +125°C −14.1 −14 V
Output Current IOUT V
DROPOUT < 1.2 V ±10 mA
Short-Circuit Current ISC ±35 mA
POWER SUPPLY
Power Supply Rejection Ratio
OP1177 PSRR VS = ±2.5 V to ±15 V 120 130 dB
−40°C < TA < +125°C 115 125 dB
OP2177/OP4177 PSRR VS = ±2.5 V to ±15 V 118 121 dB
−40°C < TA < +125°C 114 120 dB
Supply Current per Amplifier ISY V
O = 0 V 400 500 A
−40°C < TA < +125°C 500 600 A
DYNAMIC PERFORMANCE
Slew Rate SR RL = 2 kΩ 0.7 V/s
Gain Bandwidth Product GBP 1.3 MHz
NOISE PERFORMANCE
Voltage Noise en p-p 0.1 Hz to 10 Hz 0.4 V p-p
Voltage Noise Density en f = 1 kHz 7.9 8.5 nV/√Hz
Current Noise Density in f = 1 kHz 0.2 pA/√Hz
MULTIPLE AMPLIFIERS CHANNEL
SEPARATION CS DC 0.01 V/V
f = 100 kHz −120 dB
1 Typical values cover all parts within one standard deviation of the average value. Average values given in many competitor data sheets as “typical” give unrealistically
low estimates for parameters that can have both positive and negative values.
OP1177/OP2177/OP4177
Rev. D | Page 5 of 24
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter Rating
Supply Voltage 36 V
Input Voltage VS− to VS+
Differential Input Voltage ±Supply Voltage
Storage Temperature Range
R, RM, and RU Packages −65°C to +150°C
Operating Temperature Range
OP1177/OP2177/OP4177 −40°C to +125°C
Junction Temperature Range
R, RM, and RU Packages −65°C to +150°C
Lead Temperature, Soldering (10 sec) 300°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
THERMAL RESISTANCE
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 4. Thermal Resistance
Package Type θJA θ
JC Unit
8-Lead MSOP (RM-8)1190 44 °C/W
8-Lead SOIC_N (R-8) 158 43 °C/W
14-Lead SOIC_N (R-14) 120 36 °C/W
14-Lead TSSOP (RU-14) 240 43 °C/W
1 MSOP is only available in tape and reel.
ESD 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 this product 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.
OP1177/OP2177/OP4177
Rev. D | Page 6 of 24
TYPICAL PERFORMANCE CHARACTERISTICS
INPUT OFFSETVOLTAGE (µV)
NUMBER OF AMPLIFIERS
45
40
35
30
25
20
15
10
5
–30 –20 –10 0 10 20 30 40
0
50
–40
V
SY
= ±15V
02627-007
Figure 7. Input Offset Voltage Distribution
INPUT OFFSET VOLTAGE DRIFT (µV/°C)
NUMBER OF AMPLIFIERS
80
70
60
50
40
30
20
10
0.15 0.25 0.35 0.45 0.55 0.65
0
90
0.05
V
SY
= ±15V
02627-008
Figure 8. Input Offset Voltage Drift Distribution
INPUT BIAS CURRENT (nA)
NUMBER OF AMPLIFIERS
120
100
80
60
40
20
0.10.20.30.40.50.60.7
0
140
0
V
SY
= ±15V
02627-009
Figure 9. Input Bias Current Distribution
LOAD CURRENT (mA)
ΔOUTPUT VOLTAGE (V)
0.01 0.1 1
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
1.8
0.001 10
SOURCE
SINK
V
SY
= ±15V
T
A
= 25°C
02627-010
Figure 10. Output Voltage to Supply Rail vs. Load Current
TEMPERATURE (°C)
V
SY
= ±15V
INPUT BIAS CURRENT (nA)
2
1
0
–1
–2
0 50 100
3
–3
–50 150
0
2627-011
Figure 11. Input Bias Current vs. Temperature
FREQUENCY (Hz)
PHASE SHIFT (Degrees)
OPEN-LOOP GAIN (dB)
1M
50
40
30
20
10
0
–10
60
–20
100k 10M
225
180
135
90
45
0
–45
270
–90
GAIN
PHASE
V
SY
= ±15V
C
L
= 0
R
L
=
02627-012
Figure 12. Open-Loop Gain and Phase Shift vs. Frequency
OP1177/OP2177/OP4177
Rev. D | Page 7 of 24
FREQUENCY (Hz)
CLOSED-LOOP GAIN (dB)
10k 100k 1M 10M
100
80
60
40
20
0
–20
–40
–60
120
–80
1k 100M
V
SY
= ±15V
V
IN
= 4mV p-p
C
L
= 0
R
L
=
A
V
= 100
A
V
= 1
A
V
= 10
02627-013
Figure 13. Closed-Loop Gain vs. Frequency
FREQUENCY (Hz)
OUTPUT IMPEDANCE ()
1k 10k 100k 1M
450
400
350
300
250
200
150
100
50
100
500
0
VSY = ±15V
VIN = 50mV p-p
A
V
= 10
A
V
= 100
A
V
= 1
0
2627-014
Figure 14. Output Impedance vs. Frequency
TIME (100µs/DIV)
VOLTAGE (1V/DIV)
GND
V
SY
= ±15V
C
L
= 300pF
R
L
= 2k
V
IN
= 4V
A
V
= 1
02627-015
Figure 15. Large Signal Transient Response
TIME (100µs/DIV)
VOLTAGE (100mV/DIV)
GND
VSY = ±15V
CL = 1,000pF
RL = 2k
VIN = 100mV
AV = 1
02627-016
Figure 16. Small Signal Transient Response
CAPACITANCE (pF)
SMALL SIGNAL OVERSHOOT (%)
10 100 1k
1 10k
45
40
35
30
25
20
15
10
5
50
0
+OS
–OS
V
SY
= ±15V
R
L
= 2k
V
IN
= 100mV p-p
02627-017
Figure 17. Small Signal Overshoot vs. Load Capacitance
TIME (10µs/DIV)
+200m
V
0V
–15V
0V
V
SY
= ±15V
R
L
= 10k
A
V
= –100
V
IN
= 200mV
INPUT
OUTPUT
0
2627-018
Figure 18. Positive Overvoltage Recovery
OP1177/OP2177/OP4177
Rev. D | Page 8 of 24
TIME (4µs/DIV)
0V
200m
V
0V
15V
V
SY
= ±15V
R
L
= 10k
A
V
= –100
V
IN
= 200mV
INPUT
OUTPUT
0
2627-019
Figure 19. Negative Overvoltage Recovery
FREQUENCY (Hz)
CMRR (dB)
100 1k 10k 100k 1M
120
100
80
60
40
20
140
0
10 10M
V
SY
= ±15V
0
2627-020
Figure 20. CMRR vs. Frequency
FREQUENCY (Hz)
PSRR (dB)
100 1k 10k 100k 1M
120
100
80
60
40
20
140
0
10 10M
V
SY
= ±15V
+PSRR
–PSRR
02627-021
Figure 21. PSRR vs. Frequency
V
NOISE
(0.2µV/DIV)
TIME (1s/DIV)
V
SY
= ±15V
0
2627-022
Figure 22. 0.1 Hz to 10 Hz Input Voltage Noise
FREQUENCY (Hz)
16
14
12
10
8
6
4
18
2
50 100 150 2000 250
V
SY
= ±15V
VOLTAGE NOISE DENSITY (nV/
Hz)
02627-023
Figure 23. Voltage Noise Density vs. Frequency
SHORT-CIRCUIT CURRENT (mA)
+I
SC
–I
SC
TEMPERATUREC)
30
25
20
15
10
5
0 50 100
35
0
–50 150
V
SY
= ±15V
0
2627-024
Figure 24. Short-Circuit Current vs. Temperature
OP1177/OP2177/OP4177
Rev. D | Page 9 of 24
OUTPUT VOLTAGE SWING (V)
14.40
14.00
14.30
14.05
14.25
14.20
14.15
14.10
14.35
+V
OH
–V
OL
TEMPERATURE (°C)
0 50 100–50 150
V
SY
= ±15V
02627-025
Figure 25. Output Voltage Swing vs. Temperature
TIME FROM POWER SUPPLY TURN-ON (Sec)
ΔOFFSET VOLTAGE (µV)
0.4
0.3
0.2
0.1
0
–0.1
–0.2
–0.3
0.5
–0.5
–0.4
20 40 60 80 100 120
01
40
V
SY
= ±15V
02627-026
Figure 26. Warm-Up Drift
INPUT OFFSET VOLTAGE (µV)
0
12
8
4
14
18
2
6
10
16
TEMPERATURE (°C)
V
SY
= ±15V
0 50 100–50 150
02627-027
Figure 27. Input Offset Voltage vs. Temperature
CMRR (dB)
123
127
125
128
129
124
126
130
131
132
133
TEMPERATURE (°C)
VSY = ±15V
0 50 100–50 150
0
2627-028
Figure 28. CMRR vs. Temperature
PSRR (dB)
123
127
125
128
129
124
126
130
131
132
133
TEMPERATURE (°C)
V
SY
= ±15V
0 50 100–50 150
02627-029
Figure 29. PSRR vs. Temperature
INPUT OFFSET VOLTAGE (µV)
NUMBER OF AMPLIFIERS
50
15
0
45
20
10
5
30
25
40
35
V
SY
= ±5V
–40 –30 –20 –10 0 10 20 30 40
0
2627-030
Figure 30. Input Offset Voltage Distribution
OP1177/OP2177/OP4177
Rev. D | Page 10 of 24
ΔOUTPUT VOLTAGE (V)
LOAD CURRENT (mA)
1.4
0.8
0
0.4
0.2
0.6
1.0
1.2
0.01 0.1 1
V
SY
= ±5V
T
A
= 25°C
SINK
SOURCE
0.001 10
02627-031
Figure 31. Output Voltage to Supply Rail vs. Load Current
0
2627-032
FREQUENCY (Hz)
PHASE SHIFT (Degrees)
OPEN-LOOP GAIN (dB)
1M
50
40
30
20
10
0
–10
60
–20
100k 10M
225
180
135
90
45
0
–45
270
–90
GAIN
PHASE
V
SY
= ±5V
C
L
= 0
R
L
=
Figure 32. Open-Loop Gain and Phase Shift vs. Frequency
FREQUENCY (Hz)
CLOSED-LOOP GAIN (dB)
10k 100k 1M 10M
100
80
60
40
20
0
–20
–40
–60
120
–80
1k 100M
V
SY
= ±5V
V
IN
= 4mV p-p
C
L
= 0
R
L
=
A
V
= 100
A
V
= 1
A
V
= 10
0
2627-033
Figure 33. Closed-Loop Gain vs. Frequency
FREQUENCY (Hz)
OUTPUT IMPEDANCE ()
1k 10k 100k
100 1M
450
400
350
300
250
200
150
100
50
500
0
V
SY
= ±5V
V
IN
= 50mV p-p
A
V
= 100 A
V
= 1
A
V
= 10
02627-034
Figure 34. Output Impedance vs. Frequency
TIME (100µs/DIV)
VOLTAGE (1V/DIV)
GND
V
SY
= ±5V
C
L
= 300pF
R
L
= 2k
V
IN
= 1V
A
V
= 1
02627-035
Figure 35. Large Signal Transient Response
TIME (10µs/DIV)
VOLTAGE (50mV/DIV)
GND
V
SY
= ±5V
C
L
= 1,000pF
R
L
= 2k
V
IN
= 100mV
A
V
= 1
02627-036
Figure 36. Small Signal Transient Response
OP1177/OP2177/OP4177
Rev. D | Page 11 of 24
CAPACITANCE (pF)
SMALL SIGNAL OVERSHOOT (%)
10 100 1k
1 10k
45
40
35
30
25
20
15
10
5
50
0
+OS
–OS
V
SY
= ±5V
R
L
= 2k
V
IN
= 100mV
02627-037
Figure 37. Small Signal Overshoot vs. Load Capacitance
TIME (4µs/DIV)
+200mV
0V
–15V
0V
V
SY
= ±5V
R
L
= 10k
A
V
= –100
V
IN
= 200mV
INPUT
OUTPUT
02627-038
Figure 38. Positive Overvoltage Recovery
TIME (4µs/DIV)
0V
200m
V
0V
5V
V
SY
= ±5V
R
L
= 10k
A
V
= –100
V
IN
= 200mV
INPUT
OUTPUT
02627-039
Figure 39. Negative Overvoltage Recovery
TIME (200µs/DIV)
VOLTAGE (2V/DIV)
GND
V
S
= ±5V
A
V
= 1
R
L
= 10k
INPUT
OUTPUT
02627-040
Figure 40. No Phase Reversal
FREQUENCY (Hz)
CMRR (dB)
100 1k 10k 100k 1M
120
100
80
60
40
20
140
0
10 10M
V
SY
= ±5V
02627-041
Figure 41. CMRR vs. Frequency
FREQUENCY (Hz)
PSRR (dB)
100 1k 10k 100k 1M
160
120
80
40
200
0
10 10M
V
SY
= ±5V
140
100
60
20
180
+PSRR
–PSRR
02627-042
Figure 42. PSRR vs. Frequency
OP1177/OP2177/OP4177
Rev. D | Page 12 of 24
V
NOISE
(0.2µV/DIV)
TIME (1s/DIV)
V
SY
= ±5V
02627-043
Figure 43. 0.1 Hz to 10 Hz Input Voltage Noise
FREQUENCY (Hz)
16
14
12
10
8
6
4
18
2
50 100 150 2000 250
VSY = ±5V
VOLTAGE NOISE DENSITY (nV/Hz)
02627-044
Figure 44. Voltage Noise Density vs. Frequency
SHORT-CIRCUIT CURRENT (mA)
+I
SC
–I
SC
TEMPERATUREC)
30
25
20
15
10
5
0 50 100
35
0
–50 150
V
SY
= ±5V
02627-045
Figure 45. Short-Circuit Current vs. Temperature
OUTPUT VOLTAGE SWING (V)
4.40
4.00
4.30
4.05
4.25
4.20
4.15
4.10
4.35
+V
OH
–V
OL
TEMPERATURE (°C)
0 50 100–50 150
V
SY
= ±5V
02627-046
Figure 46. Output Voltage Swing vs. Temperature
INPUT OFFSET VOLTAGE (µV)
0
10
5
20
25
15
TEMPERATURE (°C)
V
SY
= ±5V
0 50 100–50 150
02627-047
Figure 47. Input Offset Voltage vs. Temperature
SUPPLY CURRENT (µA)
0
300
200
500
600
400
TEMPERATURE (°C)
0 50 100–50 150
100
V
SY
= ±5V
V
SY
= ±15V
02627-048
Figure 48. Supply Current vs. Temperature
OP1177/OP2177/OP4177
Rev. D | Page 13 of 24
SUPPLY CURRENT (µA)
0
300
200
100
350
450
50
150
250
400
SUPPLY VOLTAGE (V)
5101502025 30 35
T
A
= 25°C
0
2627-049
Figure 49. Supply Current vs. Supply Voltage
FREQUENCY (Hz)
CHANNEL SEPARATION (dB)
100 1k 10k 100k
–20
–40
–60
–80
–100
–120
–140
0
–160
10 1M
02627-050
Figure 50. Channel Separation vs. Frequency
OP1177/OP2177/OP4177
Rev. D | Page 14 of 24
FUNCTIONAL DESCRIPTION
The OPx177 series is the fourth generation of Analog Devices,
Inc., industry-standard OP07 amplifier family. OPx177 is a very
high precision, low noise operational amplifier with the highly
desirable combination of extremely low offset voltage and very
low input bias currents. Unlike JFET amplifiers, the low bias
and offset currents are relatively insensitive to ambient
temperatures, even up to 125°C.
For the first time, Analog Devices proprietary process technology
and linear design expertise have produced a high voltage
amplifier with superior performance to the OP07, OP77, and
OP177 in a tiny MSOP 8lead package. Despite its small size, the
OPx177 offers numerous improvements, including low wide-
band noise, very wide input and output voltage range, lower input
bias current, and complete freedom from phase inversion.
OPx177 has the widest specified operating temperature range of
any similar device in a plastic surface-mount package. This is
increasingly important as PC board and overall system sizes
continue to shrink, causing internal system temperatures to rise.
Power consumption is reduced by a factor of four from the
OP177, and bandwidth and slew rate increase by a factor of two.
The low power dissipation and very stable performance vs.
temperature also act to reduce warm-up drift errors to
insignificant levels.
Open-loop gain linearity under heavy loads is superior to
competitive parts, such as the OPA277, improving dc accuracy
and reducing distortion in circuits with high closed-loop gains.
Inputs are internally protected from overvoltage conditions
referenced to either supply rail.
Like any high performance amplifier, maximum performance is
achieved by following appropriate circuit and PC board
guidelines. The following sections provide practical advice on
getting the most out of the OPx177 under a variety of
application conditions.
TOTAL NOISE-INCLUDING SOURCE RESISTORS
The low input current noise and input bias current of the
OPx177 make it useful for circuits with substantial input source
resistance. Input offset voltage increases by less than 1 µV
maximum per 500 Ω of source resistance.
The total noise density of the OPx177 is
()
SS
nn
TOTALn kTRRiee 4
2
2
,++=
where:
en is the input voltage noise density.
in is the input current noise density.
RS is the source resistance at the noninverting terminal.
k is Boltzmanns constant (1.38 × 10−23 J/K).
T is the ambient temperature in Kelvin (T = 273 + °C).
For RS < 3.9 kΩ, en dominates and
en,TOTALen
For 3.9 kΩ < RS < 412 kΩ, voltage noise of the amplifier, current
noise of the amplifier translated through the source resistor, and
thermal noise from the source resistor all contribute to the total
noise.
For RS > 412 kΩ, the current noise dominates and
en,TOTALinRS
The total equivalent rms noise over a specific bandwidth is
expressed as
(
)
BWeE TOTALn
n ,
=
where BW is the bandwidth in Hertz.
The preceding analysis is valid for frequencies larger than
50 Hz. When considering lower frequencies, flicker noise (also
known as 1/f noise) must be taken into account.
For a reference on noise calculations, refer to the Band-Pass
KRC or Sallen-Key Filter section.
GAIN LINEARITY
Gain linearity reduces errors in closed-loop configurations. The
straighter the gain curve, the lower the maximum error over the
input signal range is. This is especially true for circuits with
high closed-loop gains.
The OP1177 has excellent gain linearity even with heavy loads,
as shown in Figure 51. Compare its performance to the
OPA277, shown in Figure 52. Both devices are measured under
identical conditions, with RL = 2 kΩ. The OP2177 (dual) has
virtually no distortion at lower voltages. Compared to the
OPA277 at several supply voltages and various loads, OP1177
performance far exceeds that of its counterpart.
(5V/DIV)
OP1177
(10µV/DIV)
V
SY
= ±15V
R
L
= 2k
02627-051
Figure 51. Gain Linearity
OP1177/OP2177/OP4177
Rev. D | Page 15 of 24
(5V/DIV)
OPA277
V
SY
= ±15V
R
L
= 2k
(10µV/DIV)
0
2627-052
Figure 52. Gain Linearity
INPUT OVERVOLTAGE PROTECTION
When their input voltage exceeds the positive or negative
supply voltage, most amplifiers require external resistors to
protect them from damage.
The OPx177 has internal protective circuitry that allows
voltages as high as 2.5 V beyond the supplies to be applied at the
input of either terminal without any harmful effects
Use an additional resistor in series with the inputs if the voltage
exceeds the supplies by more than 2.5 V. The value of the
resistor can be determined from the formula
(
)
mA5
500
Ω+
S
S
IN
R
VV
With the OPx177 low input offset current of <1 nA maximum,
placing a 5 kΩ resistor in series with both inputs adds less than
5 µV to input offset voltage and has a negligible impact on the
overall noise performance of the circuit.
5 kΩ protects the inputs to more than 27 V beyond either
supply. Refer to the THD + Noise section for additional
information on noise vs. source resistance.
OUTPUT PHASE REVERSAL
Phase reversal is defined as a change of polarity in the amplifier
transfer function. Many operational amplifiers exhibit phase
reversal when the voltage applied to the input is greater than the
maximum common-mode voltage. In some instances, this can
cause permanent damage to the amplifier. In feedback loops, it
can result in system lockups or equipment damage. The OPx177
is immune to phase reversal problems even at input voltages
beyond the supplies.
V
SY
=10V
A
V
= 1
TIME (400µs/DIV)
V
IN
V
OUT
VOL
T
AGE (5V/DIV)
02627-053
Figure 53. No Phase Reversal
SETTLING TIME
Settling time is defined as the time it takes an amplifier output
to reach and remain within a percentage of its final value after
application of an input pulse. It is especially important in
measurement and control circuits in which amplifiers buffer
analog-to-digital inputs or digital-to-analog converter outputs.
To minimize settling time in amplifier circuits, use proper
bypassing of power supplies and an appropriate choice of circuit
components. Resistors should be metal film types, because they
have less stray capacitance and inductance than their wire-
wound counterparts. Capacitors should be polystyrene or
polycarbonate types to minimize dielectric absorption.
The leads from the power supply should be kept as short as
possible to minimize capacitance and inductance. The OPx177
has a settling time of about 45 µs to 0.01% (1 mV) with a 10 V
step applied to the input in a noninverting unity gain.
OVERLOAD RECOVERY TIME
Overload recovery is defined as the time it takes the output
voltage of an amplifier to recover from a saturated condition to
its linear response region. A common example is one in which
the output voltage demanded by the circuits transfer function
lies beyond the maximum output voltage capability of the
amplifier. A 10 V input applied to an amplifier in a closed-loop
gain of 2 demands an output voltage of 20 V. This is beyond the
output voltage range of the OPx177 when operating at ±15 V
supplies and forces the output into saturation.
Recovery time is important in many applications, particularly
where the operational amplifier must amplify small signals in
the presence of large transient voltages.