OP27GP+ - MAXIM INTEGRATED PRODUCTS

Low Noise, Precision

Operational Amplifier

Data Sheet

OP27

Rev. H Document Feedback

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FEATURES

Low noise: 80 nV p-p (0.1 Hz to 10 Hz), 3 nV/√Hz

Low drift: 0.2 µV/°C

High speed: 2.8 V/µs slew rate, 8 MHz gain bandwidth

Low VOS: 10 µV

CMRR: 126 dB at VCM of ±11 V

High open-loop gain: 1.8 million

Available in die form

GENERAL DESCRIPTION

The OP27 precision operational amplifier combines the low

offset and drift of the OP07 with both high speed and low noise.

Offsets down to 25 µV and maximum drift of 0.6 µV/°C make

the OP27 ideal for precision instrumentation applications. Low

noise, en = 3.5 nV/√Hz, at 10 Hz, a low 1/f noise corner

frequency of 2.7 Hz, and high gain (1.8 million), allow accurate

high-gain amplification of low-level signals. A gain bandwidth

product of 8 MHz and a 2.8 V/µs slew rate provide excellent

dynamic accuracy in high speed, data-acquisition systems.

A low input bias current of ±10 nA is achieved by use of a bias

current cancellation circuit. Over the military temperature

range, this circuit typically holds IB and IOS to ±20 nA and 15 nA,

respectively.

The output stage has good load driving capability. A guaranteed

swing of ±10 V into 600 Ω and low output distortion make the

OP27 an excellent choice for professional audio applications.

(Continued on Page 3)

PIN CONFIGURATIONS

V+

OUT

4V– (CASE)

BAL

BAL 1

–IN 2

+IN 3

OP27

NC = NO CONNECT

00317-001

Figure 1. 8-Lead TO-99 (J-Suffix)

NC = NO CONNECT

TRIM

–IN

+IN

TRIM

V+

OUT

NCV–

OP27

00317-002

Figure 2. 8-Lead CERDIP – Glass Hermetic Seal (Z-Suffix),

8-Lead PDIP (P-Suffix), and 8-Lead SOIC (S-Suffix)

FUNCTIONAL BLOCK DIAGRAM

ADJ.

NONINVERTING

INPUT (+)

INVERTING

INPUT (–)

V–

V+

Q2B

Q2A

Q1A Q1B

R3 1 8

R1 AND R2 ARE PERMANENTLY

ADJUSTED AT WAFER TEST FOR

MINIMUM OFFSET VOLTAGE

Q21

R23 R24

Q23 Q24

Q22

Q11 Q12

Q27 Q28

R12

C3 C4

Q26

Q20 Q19

Q46

Q45

OUTPUT

00317-003

Figure 3.

OP27 Data Sheet

Rev. H | Page 2 of 21

TABLE OF CONTENTS

Features .............................................................................................. 1

General Description ......................................................................... 1

Pin Configurations ........................................................................... 1

Functional Block Diagram .............................................................. 1

Revision History ............................................................................... 2

Specifications ..................................................................................... 4

Electrical Characteristics ............................................................. 4

Typical Electrical Characteristics ............................................... 6

Absolute Maximum Ratings ............................................................ 7

Thermal Resistance ...................................................................... 7

ESD Caution .................................................................................. 7

Typical Performance Characteristics ..............................................8

Applications Information .............................................................. 14

Offset Voltage Adjustment ........................................................ 14

Noise Measurements .................................................................. 14

Unity-Gain Buffer Applications ............................................... 14

Comments On Noise ................................................................. 15

Audio Applications .................................................................... 16

References .................................................................................... 18

Outline Dimensions ....................................................................... 19

Ordering Guide .......................................................................... 21

REVISION HISTORY

10/15—Rev. G to Rev. H

Changes to Features Section and General Description Section ..... 1

Changes to Note 1, Ordering Guide ................................................. 21

3/15—Rev. F to Rev. G

Changes to General Description Section ...................................... 3

Changes to Figure 31 ...................................................................... 12

Changes to Applications Information Section and Output

Voltage Adjustment Section .......................................................... 14

Updated Outline Dimensions ....................................................... 19

Changes to Ordering Guide .......................................................... 21

5/06—Rev. E to Rev. F

Removed References to 745 .............................................. Universal

Updated 741 to AD741 ...................................................... Universal

Changes to Ordering Guide .......................................................... 20

12/05—Rev. D to Rev. E

Edits to Figure 2 ................................................................................ 1

9/05—Rev. C to Rev. D

Updated Format .................................................................. Universal

Changes to Table 1 ............................................................................ 4

Removed Die Characteristics Figure ............................................. 5

Removed Wafer Test Limits Table .................................................. 5

Changes to Table 5 ............................................................................ 7

Changes to Comments on Noise Section .................................... 15

Changes to Ordering Guide .......................................................... 24

1/03—Rev. B to Rev. C

Edits to Pin Connections .................................................................. 1

Edits to General Description ........................................................... 1

Edits to Die Characteristics .............................................................. 5

Edits to Absolute Maximum Ratings .............................................. 7

Updated Outline Dimensions ....................................................... 16

Edits to Figure 8 .............................................................................. 14

Edits to Outline Dimensions......................................................... 16

9/01—Rev. 0 to Rev. A

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 .............................................. 2, 3

Edits to Wafer Test Limits ................................................................ 4

Deleted Typical Electrical Characteristics...................................... 4

Edits to Burn-In Circuit Figure ....................................................... 7

Edits to Application Information .................................................... 8

Data Sheet OP27

Rev. H | Page 3 of 21

GENERAL DESCRIPTION

(Continued from Page 1)

PSRR and CMRR exceed 120 dB. These characteristics, coupled

with long-term drift of 0.2 µV/month, allow the circuit designer

to achieve performance levels previously attained only by discrete

designs.

Low cost, high volume production of OP27 is achieved by

using an on-chip Zener zap-trimming network. This reliable

and stable offset trimming scheme has proven its effectiveness

over many years of production history.

The OP27 provides excellent performance in low noise,

high accuracy amplification of low level signals. Applications

include stable integrators, precision summing amplifiers,

precision voltage threshold detectors, comparators, and

professional audio circuits such as tape heads and microphone

preamplifiers.

OP27 Data Sheet

Rev. H | Page 4 of 21

SPECIFICATIONS

ELECTRICAL CHARACTERISTICS

VS = ±15 V, TA = 25°C, unless otherwise noted.

Table 1.

OP27A/OP27E OP27G

Parameter

Symbol

Test Conditions

Min

Typ

Max

Min

Typ

Max

Unit

INPUT OFFSET VOLTAGE

100

µV

LONG-TERM VOS STABILITY2, 3 VOS/Time 0.2 1.0 0.4 2.0 µV/MO

INPUT OFFSET CURRENT IOS 7 35 12 75 nA

INPUT BIAS CURRENT IB ±10 ±40 ±15 ±80 nA

INPUT NOISE VOLTAGE3, 4 en p-p 0.1 Hz to 10 Hz 0.08 0.18 0.09 0.25 µV p-p

INPUT NOISE en fO = 10 Hz 3.5 5.5 3.8 8.0 nV/√Hz

Voltage Density3 fO = 30 Hz 3.1 4.5 3.3 5.6 nV/√Hz

fO = 1000 Hz 3.0 3.8 3.2 4.5 nV/√Hz

INPUT NOISE in fO = 10 Hz 1.7 4.0 1.7 pA/√Hz

Current Density3 fO = 30 Hz 1.0 2.3 1.0 pA/√Hz

fO = 1000 Hz 0.4 0.6 0.4 0.6 pA/√Hz

INPUT RESISTANCE

Differential Mode5 RIN 1.3 6 0.7 4 MΩ

Common Mode RINCM 3 2 GΩ

INPUT VOLTAGE RANGE IVR ±11.0 ±12.3 ±11.0 ±12.3 V

COMMON-MODE REJECTION RATIO CMRR VCM = ±11 V 114 126 100 120 dB

POWER SUPPLY REJECTION RATIO PSRR VS = ±4 V to ±18 V 1 10 2 20 µV/V

LARGE SIGNAL VOLTAGE GAIN AVO RL ≥ 2 kΩ, VO = ±10 V 1000 1800 700 1500 V/mV

RL ≥ 600 Ω, VO = ±10 V 800 1500 600 1500 V/mV

OUTPUT VOLTAGE SWING VO RL ≥ 2 kΩ ±12.0 ±13.8 ±11.5 ±13.5 V

RL ≥ 600 Ω ±10.0 ±11.5 ±10.0 ±11.5 V

SLEW RATE6 SR RL ≥ 2 kΩ 1.7 2.8 1.7 2.8 V/µs

GAIN BANDWIDTH PRODUCT6 GBW 5.0 8.0 5.0 8.0 MHz

OPEN-LOOP OUTPUT RESISTANCE RO VO = 0, IO = 0 70 70 Ω

POWER CONSUMPTION Pd VO 90 140 100 170 mW

OFFSET ADJUSTMENT RANGE RP = 10 kΩ ±4.0 ±4.0 mV

1 Input offset voltage measurements are performed 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 VOS vs. time over extended periods after the first 30 days of operation. Excluding the initial

hour of operation, changes in VOS during the first 30 days are typically 2.5 µV. Refer to the Typical Performance Characteristics section.

3 Sample tested.

4 See voltage noise test circuit (Figure 31).

5 Guaranteed by input bias current.

6 Guaranteed by design.

Data Sheet OP27

Rev. H | Page 5 of 21

VS = ±15 V, −55°C ≤ TA ≤ 125°C, unless otherwise noted.

Table 2.

OP27A

Parameter Symbol Test Conditions Min Typ Max Unit

INPUT OFFSET VOLTAGE1 VOS 30 60 µV

AVERAGE INPUT OFFSET DRIFT TCVOS2

TCVOSn3 0.2 0.6 µV/°C

INPUT OFFSET CURRENT IOS 15 50 nA

INPUT BIAS CURRENT IB ±20 ±60 nA

INPUT VOLTAGE RANGE IVR ±10.3 ±11.5 V

COMMON-MODE REJECTION RATIO CMRR VCM = ±10 V 108 122 dB

POWER SUPPLY REJECTION RATIO PSRR VS = ±4.5 V to ±18 V 2 16 µV/V

LARGE SIGNAL VOLTAGE GAIN AVO RL ≥ 2 kΩ, VO = ±10 V 600 1200 V/mV

OUTPUT VOLTAGE SWING VO RL ≥ 2 kΩ ±11.5 ±13.5 V

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 TCVOS performance is within the specifications unnulled or when nulled with RP = 8 kΩ to 20 kΩ. TCVOS is 100% tested for A/E grades, sample tested for G grades.

3 Guaranteed by design.

VS = ±15 V, −25°C ≤ TA ≤ 85°C for OP27J and OP27Z and −40°C ≤ TA ≤ 85°C for OP27GS, unless otherwise noted.

Table 3.

OP27E OP27G

Parameter Symbol Test Conditions Min Typ Max Min Typ Max Unit

INPUT ONSET VOLTAGE VOS 20 50 55 220 µV

AVERAGE INPUT OFFSET DRIFT TCVOS1 0.2 0.6 0 4 1.8 µV/°C

TCVOSn2 0.2 0.6 0 4 1.8 µV/°C

INPUT OFFSET CURRENT IOS 10 50 20 135 nA

INPUT BIAS CURRENT IB ±14 ±60 ±25 ±150 nA

INPUT VOLTAGE RANGE IVR ±10.5 ±11.8 ±10.5 ±11.8 V

COMMON-MODE REJECTION RATIO

CMRR

= ±10 V

110

124

118

POWER SUPPLY REJECTION RATIO PSRR VS = ±4.5 V to ±18 V 2 15 2 32 µV/V

LARGE SIGNAL VOLTAGE GAIN AVO RL ≥ 2 kΩ, VO = ±10 V

750 1500 450 1000 V/mV

OUTPUT VOLTAGE SWING

≥ 2 kΩ

±11.7

±13.6

±11.0

±13.3

1 The TCVOS performance is within the specifications unnulled or when nulled with RP = 8 kΩ to 20 kΩ. TCVOS is 100% tested for A/E grades, sample tested for C/G grades.

2 Guaranteed by design.

OP27 Data Sheet

Rev. H | Page 6 of 21

TYPICAL ELECTRICAL CHARACTERISTICS

VS = ±15 V, TA = 25°C unless otherwise noted.

Table 4.

Parameter Symbol Test Conditions OP27N Typical Unit

AVERAGE INPUT OFFSET VOLTAGE DRIFT1 TCVOS or TCVOSn Nulled or unnulled, RP = 8 kΩ to 20 kΩ 0.2 µV/°C

AVERAGE INPUT OFFSET CURRENT DRIFT TCIOS 80 pA/°C

AVERAGE INPUT BIAS CURRENT DRIFT TCIB 100 pA/°C

INPUT NOISE VOLTAGE DENSITY en fO = 10 Hz 3.5 nV/√Hz

fO = 30 Hz 3.1 nV/√Hz

fO = 1000 Hz 3.0 nV/√Hz

INPUT NOISE CURRENT DENSITY in fO = 10 Hz 1.7 pA/√Hz

fO = 30 Hz 1.0 pA/√Hz

fO = 1000 Hz 0.4 pA/√Hz

INPUT NOISE VOLTAGE SLEW RATE enp-p 0.1 Hz to 10 Hz 0.08 µV p-p

SR RL ≥ 2 kΩ 2.8 V/µs

GAIN BANDWIDTH PRODUCT GBW 8 MHz

1 Input offset voltage measurements are performed by automated test equipment approximately 0.5 seconds after application of power.

Data Sheet OP27

Rev. H | Page 7 of 21

ABSOLUTE MAXIMUM RATINGS

Table 5.

Parameter Rating

Supply Voltage ±22 V

Input Voltage1±22 V

Output Short-Circuit Duration Indefinite

Differential Input Voltage2 ±0.7 V

Differential Input Current2 ±25 mA

Storage Temperature Range −65°C to +150°C

Operating Temperature Range

OP27A (J, Z)

−55°C to +125°C

OP27E (Z) −25°C to +85°C

OP27E (P) 0°C to 70°C

OP27G (P, S, J, Z) −40°C to +85°C

Lead Temperature Range (Soldering, 60 sec) 300°C

Junction Temperature

−65°C to +150°C

1 For supply voltages less than ±22 V, the absolute maximum input voltage is

equal to the supply voltage.

2 The inputs of the OP27 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.

Stresses at or above those listed under Absolute Maximum

Ratings may cause permanent damage to the product. This is a

stress rating only; functional operation of the product at these

or any other conditions above those indicated in the operational

section of this specification is not implied. Operation beyond

the maximum operating conditions for extended periods may

affect product reliability.

THERMAL RESISTANCE

θJA is specified for the worst-case conditions, that is, θJA is

specified for device in socket for TO-99, CERDIP, and PDIP

packages; θJA is specified for device soldered to printed circuit

board for SOIC package.

Absolute maximum ratings apply to both dice and packaged

parts, unless otherwise noted.

Table 6.

Package Type θJA θJC Unit

8-Lead Metal Can (TO-99) (J) 150 18 °C/W

8-Lead CERDIP (Z) 148 16 °C/W

8-Lead PDIP (P) 103 43 °C/W

8-Lead SOIC_N (S) 158 43 °C/W

ESD CAUTION

OP27 Data Sheet

Rev. H | Page 8 of 21

TYPICAL PERFORMANCE CHARACTERISTICS

100

0.01 0.1 1 10 100

FREQUENCY (Hz)

GAIN (dB)

TEST TIME OF 10sec FURTHER

LIMITS LOW FREQUENCY

(<0.1Hz) GAIN

00317-004

Figure 4. 0.1 Hz to 10 Hz p-p Noise Tester Frequency Response

1 10 100 1k

FREQUENCY (Hz)

VOLTAGE NOISE (nV/Hz)

I/F CORNER = 2.7Hz

TA = 25qC

VS = r15V

00317-005

Figure 5. Voltage Noise Density vs. Frequency

INSTRUMENTATION

RANGE TO DC

AUDIO RANGE

TO 20kHz

741

OP27 I/F CORNER

I/F CORNER = 2.7Hz

I/F CORNER

LOW NOISE

AUDIO OP AMP

100

1 10 100 1k

FREQUENCY (Hz)

VOLTAGE NOISE (nV/Hz)

00317-006

Figure 6. A Comparison of Op Amp Voltage Noise Spectra

0.1

0.01

100 1k 10k 100k

BANDWIDTH (Hz)

RMS VOLTAGE NOISE (PV)

TA = 25qC

VS = r15V

00317-007

Figure 7. Input Wideband Voltage Noise vs. Bandwidth (0.1 Hz to Frequency

Indicated)

100

100 1k 10k

SOURCE RESISTANCE (:)

TOTAL NOISE (nV/Hz)

TA = 25qC

VS = r15V

– 2R1

RESISTOR NOISE ONLY

AT 1kHz

AT 10Hz

00317-008

Figure 8. Total Noise vs. Sourced Resistance

–50 0–25 100755025 125

TEMPERATURE (qC)

VOLTAGE NOISE (nV/Hz)

AT 10Hz

AT 1kHz

= r15V

00317-009

Figure 9. Voltage Noise Density vs. Temperature

Data Sheet OP27

Rev. H | Page 9 of 21

040

TOTAL SUPPLY VOLTAGE, V+ – V–, (V)

VOLTAGE NOISE (nV/Hz)

TA = 25qC

10 20 30

AT 10Hz

AT 1kHz

00317-010

Figure 10. Voltage Noise Density vs. Supply Voltage

10.0

0.1

10 10k

FREQUENCY (Hz)

CURRENT NOISE (pA/Hz)

I/F CORNER = 140Hz

1.0

100 1k

00317-011

Figure 11. Current Noise Density vs. Frequency

5.0

1.0

545

TOTAL SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

TA = –55qC

TA = +125qC

4.0

3.0

2.0

15 25 35

TA = +25qC

00317-012

Figure 12. Supply Current vs. Supply Voltage

–70

–75 175

TEMPERATURE (qC)

OFFSET VOLTAGE (PV)

–10

–20

–30

–40

–50

–60

–50 –25 0 25 50 75 100 125 150

OP27C

OP27A

TRIMMING WITH

10k: POT DOES

NOT CHANGE

TCV

00317-013

Figure 13. Offset Voltage Drift of Five Representative Units vs. Temperature

–6

TIME (Months)

CHANGE IN OFFSET VOLTAGE (PV)

–2

–4

–6

–2

–4

1 2 3 4 5 6

00317-014

Figure 14. Long-Term Offset Voltage Drift of Six Representative Units

TIME AFTER POWER ON (Min)

CHANGE IN INPUT OFFSET VOLTAGE (PV)

= 25qC

= 15V

1 2 3 4

OP27 A/E

OP27 F

OP27 C/G

00317-015

Figure 15. Warm-Up Offset Voltage Drift

OP27 Data Sheet

Rev. H | Page 10 of 21

–20 100

TIME (Sec)

OPEN-LOOP GAIN (dB)

0 20 40 60 80

THERMAL

SHOCK

RESPONSE

BAND

DEVICE IMMERSED

IN 70qC OIL BATH

25qC

= 70qC

= r15V

00317-016

Figure 16. Offset Voltage Change Due to Thermal Shock

150

TEMPERATURE (qC)

INPUT BIAS CURRENT (nA)

–50 –25 0 25 50 75 100 125

=r15V

OP27C

OP27A

00317-017

Figure 17. Input Bias Current vs. Temperature

125

TEMPERATURE (qC)

INPUT OFFSET CURRENT (nA)

–50 –25–75 0 25 50 75 100

OP27C

OP27A

=r15V

00317-018

Figure 18. Input Offset Current vs. Temperature

–10

100M

FREQUENCY (Hz)

VOLTAGE GAIN (dB)

130

10 1001 1k 10k 100k 1M 10M

110

00317-019

Figure 19. Open-Loop Gain vs. Frequency

125

TEMPERATURE (qC)

SLEW RATE (V/PS) PHASE MARGIN (Degrees)

–50 –25–75 0 25 50 75 100

=r15V

GAIN BANDWIDTH PRODUCT (MHz)

SLEW

GBW

00317-020

Figure 20. Slew Rate, Gain Bandwidth Product, Phase Margin vs.

Temperature

100M

FREQUENCY (Hz)

–10

PHASE SHIFT (Degrees)

GAIN (dB)

220

–5

100

120

140

160

180

200

10M

TA = 25qC

= r15V

GAIN

PHASE

MARGIN

= 70q

00317-021

Figure 21. Gain, Phase Shift vs. Frequency

Data Sheet OP27

Rev. H | Page 11 of 21

050

TOTAL SUPPLY VOLTAGE (V)

OPEN-LOOP GAIN (V/PV)

= 25qC

2.5

2.0

1.5

1.0

0.5

10 20 30 40

= 2k:

= 1k:

00317-022

Figure 22. Open-Loop Voltage Gain vs. Supply Voltage

1k 10M

FREQUENCY (Hz)

MAXIMUM OUTPUT SWING

TA= 25°C

VS= ±15V

10k 100k 1M

00317-023

Figure 23. Maximum Output Swing vs. Frequency

–2

100 10k

LOAD RESISTANCE (:)

MAXIMUM OUTPUT (V)

= 25qC

=r15V

POSITIVE

SWING

NEGATIVE

SWING

00317-024

Figure 24. Maximum Output Voltage vs. Load Resistance

02500

CAPACITIVE LOAD (pF)

% OVERSHOOT

100

500 1000 1500 2000

VS=r15V

VIN = 100mV

AV= +1

00317-025

Figure 25. Small-Signal Overshoot vs. Capacitive Load

50mV

–50mV

VCL

= +1

= 15pF

= r15V

= 25qC

20mV 500ns

00317-026

Figure 26. Small-Signal Transient Response

+5V

–5V

AVCL = +1

VS = r15V

TA = 25qC

2V 2Ps

00317-027

Figure 27. Large Signal Transient Response

OP27 Data Sheet

Rev. H | Page 12 of 21

TIME FROM OUTPUT SHORTED TO GROUND (Min)

SHORT-CIRCUIT CURRENT (mA)

1 2 3 4

= 25qC

= 15V

(–)

(+)

00317-028

Figure 28. Short-Circuit Current vs. Time

100 1M

FREQUENCY (Hz)

CMRR (dB)

140

120

100

1k 10k 100k

=r15V

= 25qC

=r10V

00317-029

Figure 29. CMRR vs. Frequency

–16

0r20

SUPPLY VOLTAGE (V)

COMMON-MODE RANGE (V)

= –55qC

= +125qC

= –55qC

= +125qC

= +25qC

–4

–8

–12

r5r10 r15

00317-030

Figure 30. Common-Mode Input Range vs. Supply Voltage

AD8677

OP27

D.U.T.

N

N

4.7mF

N

N

VOLTAGE

GAIN

= 50,000

2.2mF

22mF

N

SCOPE ´ 1

 0

0.1mF



N

0.1mF

00317-031

Figure 31. Voltage Noise Test Circuit (0.1 Hz to 10 Hz)

2.4

0.4

100 1k 10k 100k

LOAD RESISTANCE (:)

OPEN-LOOP VOLTAGE GAIN (V/PV)

= 25qC

= r15V

2.2

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

00317-032

Figure 32. Open-Loop Voltage Gain vs. Load Resistance

–90

–120

VOLTAGE NOISE (nV)

1 SEC/DIV

120

–40

0.1Hz TO 10Hz p-p NOISE

00317-033

Figure 33. Low Frequency Noise

Data Sheet OP27

Rev. H | Page 13 of 21

160

1100M

FREQUENCY (Hz)

POWER SUPPLY REJECTION RATIO (dB)

= 25qC

140

120

100

10 100 1k 10k 100k 1M 10M

NEGATIVE

SWING

POSITIVE

SWING

00317-034

Figure 34. PSRR vs. Frequency

OP27 Data Sheet

Rev. H | Page 14 of 21

APPLICATIONS INFORMATION

OP27 series units can be inserted directly into OP07 sockets

with or without removal of external compensation or nulling

components. OP27 offset voltage can be nulled to 0 (or another

desired setting) using a potentiometer (see Figure 35).

The OP27 provides stable operation with load capacitances of

up to 2000 pF and ±10 V swings; larger capacitances should be

decoupled with a 50 Ω resistor inside the feedback loop. The

OP27 is unity-gain stable.

Thermoelectric voltages generated by dissimilar metals at the

input terminal contacts can degrade the drift performance.

Best operation is obtained when both input contacts are

maintained at the same temperature.

–-

OP27

V–

V+

OUTPUT

10k:

00317-035

Figure 35. Offset Nulling Circuit

OFFSET VOLTAGE ADJUSTMENT

The input offset voltage of the OP27 is trimmed at wafer level.

However, if further adjustment of VOS is necessary, a 10 kΩ trim

potentiometer can be used. TCVOS is not degraded (see Figure 35).

Other potentiometer values from 1 kΩ to 1 MΩ can be used

with a slight degradation (0.1 µV/°C to 0.2 µV/°C) of TCVOS.

Trimming to a value other than zero creates a drift of approxi-

mately (VOS/300) µV/°C. For example, the change in TCVOS is

0.33 µV/°C if VOS is adjusted to 100 µV. The offset voltage

adjustment range with a 10 kΩ potentiometer is ±4 mV. If smaller

adjustment range is required, the nulling sensitivity can be

reduced by using a smaller potentiometer in conjunction with

fixed resistors. For example, Figure 36 shows a network that has

a ±280 µV adjustment range.

184.7k:4.7k:1k: POTT

V+

00317-036

Figure 36. Offset Voltage Adjustment

NOISE MEASUREMENTS

To measure the 80 nV p-p noise specification of the OP27 in

the 0.1 Hz to 10 Hz range, the following precautions must be

observed:

xThe device must be warmed up for at least five minutes.

As shown in the warm-up drift curve, the offset voltage

typically changes 4 µV due to increasing chip temperature

after power-up. In the 10-second measurement interval,

these temperature-induced effects can exceed tens-of-

nanovolts.

xFor similar reasons, the device has to be well-shielded

from air currents. Shielding minimizes thermocouple effects.

xSudden motion in the vicinity of the device can also

feedthrough to increase the observed noise.

xThe test time to measure 0.1 Hz to 10 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 10 seconds acts as an additional zero

to eliminate noise contributions from the frequency band

below 0.1 Hz.

xA noise voltage density test is recommended when

measuring noise on a large number of units. A 10 Hz noise

voltage density measurement correlates well with a 0.1 Hz to

10 Hz p-p noise reading, since both results are determined

by the white noise and the location of the 1/f corner

frequency.

UNITY-GAIN BUFFER APPLICATIONS

When Rf ≤ 100 Ω and the input is driven with a fast, large

signal pulse (>1 V), the output waveform looks as shown in the

pulsed operation diagram (see Figure 37).

During the fast feedthrough-like portion of the output, the

input protection diodes effectively short the output to the input,

and a current, limited only by the output short-circuit protect-

ion, is drawn by the signal generator. With Rf ≥ 500 Ω, the output is

capable of handling the current requirements (IL ≤ 20 mA at 10 V);

the amplifier stays in its active mode and a smooth transition

occurs.

When Rf > 2 kΩ, a pole is created with Rf and the amplifier’s

input capacitance (8 pF) that creates additional phase shift and

reduces phase margin. A small capacitor (20 pF to 50 pF) in

parallel with Rf eliminates this problem.

–

OP27

2.8V/Ps

00317-037

Figure 37. Pulsed Operation

Data Sheet OP27

Rev. H | Page 15 of 21

COMMENTS ON NOISE

The OP27 is a very low noise, monolithic op amp. The out-

standing input voltage noise characteristics of the OP27

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 OP27A/OP27E has

IB and IOS of only ±40 nA and 35 nA at 25°C respectively. 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, VOS, and TCVOS of previous

designs have made direct coupling difficult, if not impossible,

to use.

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 noise advantage of the OP27 disappears when

high source resistors are used. Figure 38, Figure 39, Figure 40

compare the observed total noise of the OP27 with the noise

performance of other devices in different circuit applications.

2/1

)(

)

(

u



NoiseResistor

RNoiseCurrent

NoiseVoltage

NoiseTotal S

Figure 38 shows noise vs. source resistance at 1000 Hz. The

same plot applies to wideband noise. To use this plot, multiply

the vertical scale by the square root of the bandwidth.

RS—SOURCE RESISTANCE (

)

50 10k

500 1k 5k

100

100 50k

OP07

5534

OP27/37

NOISE ONLY

OP08/108

1 R

UNMATCHED

e.g. R

= R

= 10k

, R

= 0

2 R

MATCHED

e.g. R

= 10k

, R

= R

= 5k

00317-038

TOTAL NOIS

E (nV/



Hz)

Figure 38. Noise vs. Source Resistance (Including Resistor Noise) at 1000 Hz

At RS < 1 kΩ, the low voltage noise of the OP27 is maintained.

With RS < 1 kΩ, total noise increases but is dominated by the

resistor noise rather than current or voltage noise. lt is only

beyond RS of 20 kΩ 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 OP27 and OP07 noise occurs in the 15 kΩ

to 40 kΩ region.

Figure 39 shows the 0.1 Hz to 10 Hz p-p noise. Here the picture

is less favorable; resistor noise is negligible and current noise

becomes important because it is inversely proportional to the

square root of frequency. The crossover with the OP07 occurs

in the 3 kΩ to 5 kΩ range depending on whether balanced or

unbalanced source resistors are used (at 3 kΩ the IB and IOS

error also can be 3× the VOS spec).

—SOURCE RESISTANCE (

)

100

50 10k

p-p NOISE (nV)

500 1k 5k

500

100 50k

1 R

UNMATCHED

e.g. R

= R

= 10k

, R

= 0

2 R

MATCHED

e.g. R

= 10k

, R S1 = RS2 = 5k

OP07

5534

OP27/37

NOISE ONLY

OP08/108

00317-039

Figure 39. Peak-to-Peak Noise (0.1 Hz to 10 Hz) as Source Resistance

(Includes Resistor Noise)

For low frequency applications, the OP07 is better than the

OP27/OP37 when RS > 3 kΩ. The only exception is when gain

error is important.

Figure 40 illustrates the 10 Hz noise. As expected, the results are

between the previous two figures.

50 10k

500 1k 5k

100

100 50k

OP07

5534

OP27/37

NOISE ONLY

OP08/108

1 R

UNMATCHED

e.g. R

= R

= 10k

, R

= 0

2 R

TCHED

e.g. R

= 10k

, R

= R

= 5k

00317-040

—SOURCE RESISTANCE (

)

TOTAL NOISE (nV/



Hz)

Figure 40. 10 Hz Noise vs. Source Resistance (Includes Resistor Noise)

Audio Applications

OP27 Data Sheet

Rev. H | Page 16 of 21

For reference, typical source resistances of some signal sources

are listed in Table 7.

Table 7.

Device

Source

Impedance Comments

Strain Gauge <500 Ω Typically used in low frequency

applications.

Magnetic

Tape Head

<1500 Ω Low is very important to reduce

self-magnetization problems

when direct coupling is used.

OP27 IB can be neglected.

Magnetic

Phonograph

Cartridges

<1500 Ω

Similar need for low I

in direct

coupled applications. OP27 does

not introduce any self-

magnetization problems.

Linear

Variable

Differential

Transformer

<1500 Ω Used in rugged servo-feedback

applications. Bandwidth of

interest is 400 Hz to 5 kHz.

Table 8. Open-Loop Gain

Frequency OP07 OP27 OP37

At 3 Hz 100 dB 124 dB 125 dB

At 10 Hz 100 dB 120 dB 125 dB

At 30 Hz 90 dB 110 dB 124 dB

AUDIO APPLICATIONS

Figure 41 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 frequency

dependent feedback around a high quality gain block. Properly

chosen, an RC network can provide the three necessary time

constants of 3180 µs, 318 µs, and 75 µs.

For initial equalization accuracy and stability, precision metal

film resistors and film capacitors of polystyrene or polypro-

pylene are recommended because they have low voltage

coefficients, dissipation factors, and dielectric absorption.

(High-k ceramic capacitors should be avoided here, though

low-k ceramics, such as NPO types that have excellent

dissipation factors and somewhat lower dielectric absorption,

can be considered for small values.)

150pF

OP27

N

MOVING MAGNET

CARTRIDGE INPUT

+ +

C4 (2)

220µF

0.03µF

0.01µF

0.47µF

LF ROLLOFF

OUT IN

OUTPUT

N

N

N

N



G = 1kHz GAIN

= 0.101 ( 1 + )

= 98.677 (39.9dB) AS SHOWN

00317-041

Figure 41. Phono Preamplifier Circuit

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 Ω, generating 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 kΩ 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:

§ R3

G1101.0

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 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 produces less than 0.03% total harmonic

distortion at frequencies up to 20 kHz.

Capacitor C3 and Resistor R4 form 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 roll-off. Placing the rumble filter’s

high-pass action after the preamplifier 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 preamplifier, though more gain is typically demanded,

along with equalization requiring a heavy low frequency boost.

The circuit in Figure 41 can be readily modified for tape use, as

shown by Figure 42.

Data Sheet OP27

Rev. H | Page 17 of 21

N

N

TAPE

HEAD

0.47µF

0.01µF



N

T1 = 3180µs

T2 = 50µs

OP27

–

00317-042

Figure 42. Tape Head Preamplifier

While the tape equalization requirement has a flat high

frequency gain above 3 kHz (T2 = 50 µs), the amplifier need

not be stabilized for unity gain. The decompensated OP37

provides a greater bandwidth and slew rate. For many applica-

tions, the idealized time constants shown can require trimming

of R1 and R2 to optimize frequency response for nonideal tape

head performance and other factors (see the References section).

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 µF output

capacitor can block this level without affecting the dynamic

range.

The tape head can be coupled directly to the amplifier input,

because the worst-case bias current of 80 nA with a 400 mH,

100 µ inch head (such as the PRB2H7K) is not troublesome.

Amplifier bias-current transients that can magnetize a head

present one potential tape head problem. The OP27 and OP37

are free of bias current transients upon power-up or power-

down. 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 kΩ. For this configuration,

the bias current induced offset voltage can be greater than the

100 pV maximum offset if the head resistance is not sufficiently

controlled.

A simple, but effective, fixed gain transformerless microphone

preamp (Figure 43) amplifies differential signals from low

impedance microphones by 50 dB and has an input impedance

of 2 kΩ. Because of the high working gain of the circuit, an

OP37 helps to preserve bandwidth, which is 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

can cause the amplifier to oscillate.

Common-mode input noise rejection will depend upon the

match of the bridge-resistor ratios. Either close tolerance (0.1%)

types should be used, or R4 should be trimmed for best CMRR.

All resistors should be metal film types for best stability and low

noise.

Noise performance of this circuit is limited more by the Input

Resistors R1 and R2 than by the op amp, as R1 and R2 each

generate a 4 nV/√Hz noise, while the op amp generates a

3.2 nV/√Hz noise. The rms sum of these predominant noise

sources is about 6 nV/√Hz, equivalent to 0.9 µV in a 20 kHz

noise bandwidth, or nearly 61 dB below a 1 mV input signal.

Measurements confirm this predicted performance.

LOW IMPEDANCE

MICROPHONE INPUT

=  T2

5mF

N

N



N

N

N

OUTPUT

OP27/

OP37

–

N

00317-043

Figure 43. Fixed Gain Transformerless Microphone Preamplifier

For applications demanding appreciably lower noise, a high

quality microphone transformer coupled preamplifier (Figure 44)

incorporates the internally compensated OP27. T1 is a JE-

115K-E 150 Ω/15 kΩ transformer that 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.

JENSEN TRANSFORMERS

OP27





1

1800pF

OUTPUT



SOURCE

T1 – JENSEN JE – 115K – E

00317-044

Figure 44. High Quality Microphone Transformer Coupled Preamplifier

Gain can 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 is very low, 1.7 mV or less, for a 40 dB gain.

The typical output blocking capacitor can be eliminated in such

cases, but it is desirable for higher gains to eliminate switching

transients.

OP27

–18V

+18V

00317-045

Figure 45. Burn-In Circuit

Capacitor C2 and Resistor R2 form a 2 µs 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 µs time constant is not

necessary, C2 can be deleted, allowing the faster OP37 to be

employed.

OP27 Data Sheet

Rev. H | Page 18 of 21

A 150 Ω resistor and R1 and R2 gain resistors connected to a

noiseless amplifier 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 is close to 3.6 dB (or −69.5 referenced to 1 mV).

REFERENCES

1. Lipshitz, S. R, “On RIAA Equalization Networks,” JAES,

Vol. 27, June 1979, p. 458–481.

2. Jung, W. G., IC Op Amp Cookbook, 2nd. Ed., H. W. Sams

and Company, 1980.

3. Jung, W. G., Audio IC Op Amp Applications, 2nd. Ed., H. W.

Sams and Company, 1978.

4. Jung, W. G., and Marsh, R. M., “Picking Capacitors,” Audio,

February and March, 1980.

5. Otala, M., “Feedback-Generated Phase Nonlinearity in

Audio Amplifiers,” London AES Convention, March 1980,

preprint 1976.

6. Stout, D. F., and Kaufman, M., Handbook of Operational

Amplifier Circuit Design, New York, McGraw-Hill, 1976.

Data Sheet OP27

Rev. H | Page 19 of 21

OUTLINE DIMENSIONS

COMPLIANT TO JEDEC STANDARDS MS-001

CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS

(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR

REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.

CORNER LEADS MAY BE CONFIGURED AS WHOLE OR HALF LEADS.

070606-A

0.022 (0.56)

0.018 (0.46)

0.014 (0.36)

SEATING

PLANE

0.015

(0.38)

MIN

0.210 (5.33)

MAX

0.150 (3.81)

0.130 (3.30)

0.115 (2.92)

0.070 (1.78)

0.060 (1.52)

0.045 (1.14)

0.280 (7.11)

0.250 (6.35)

0.240 (6.10)

0.100 (2.54)

BSC

0.400 (10.16)

0.365 (9.27)

0.355 (9.02)

0.060 (1.52)

MAX

0.430 (10.92)

MAX

0.014 (0.36)

0.010 (0.25)

0.008 (0.20)

0.325 (8.26)

0.310 (7.87)

0.300 (7.62)

0.195 (4.95)

0.130 (3.30)

0.115 (2.92)

0.015 (0.38)

GAUGE

PLANE

0.005 (0.13)

MIN

Figure 46. 8-Lead Plastic Dual-in-Line Package [PDIP]

(N-8)

P-Suffix

Dimensions shown in inches and (millimeters)

CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS

(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR

REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.

0.310 (7.87)

0.220 (5.59)

0.005 (0.13)

MIN 0.055 (1.40)

MAX

0.100 (2.54) BSC

15°

0°

0.320 (8.13)

0.290 (7.37)

0.015 (0.38)

0.008 (0.20)

SEATING

PLANE

0.200 (5.08)

MAX

0.405 (10.29) MAX

0.150 (3.81)

MIN

0.200 (5.08)

0.125 (3.18)

0.023 (0.58)

0.014 (0.36)

0.070 (1.78)

0.030 (0.76)

0.060 (1.52)

0.015 (0.38)

Figure 47. 8-Lead Ceramic DIP – Glass Hermetic Seal [CERDIP]

(Q-8)

Z-Suffix

Dimensions shown in inches and (millimeters)

OP27 Data Sheet

Rev. H | Page 20 of 21

CONTROLLING DIMENSIONS ARE I

N MILLIMETERS; INCH DIMENSIONS

(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR

REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.

COMPLIANT TO JEDEC STANDARDS MS-012-AA

012407-A

0.25 (0.0098)

0.17 (

0.0067)

1.27 (0.0500)

0.40 (0.0157)

0.50 (0.0196)

0.25 (0.0099) 45°

8°

0°

1.75 (0.0688)

1.35 (0.0532)

SEATING

PLANE

0.25 (0.0098)

0.10 (0.0040)

8 5

5.00 (0.1968)

4.80 (0.1890)

4.00 (0.1574)

3.80 (0.1497)

1.27 (0.0500)

6.20 (0.2441)

5.80 (0.2284)

0.51 (0.0201)

0.31 (0.0122)

COPLANARITY

0.10

Figure 48. 8-Lead Standard Small Outline Package [SOIC_N]

Narrow Body

(R-8)

S-Suffix

Dimensions shown in millimeters and (inches)

CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS

(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR

REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.

COMPLIANT TO JEDEC STANDARDS MO-002-AK

01-15-2015-B

0.250 (6.35) MIN

0.185 (4.70)

0.165 (4.19) 0.050 (1.27) MAX

0.019 (0.48)

0.016 (0.41)

0.040 (1.02)

0.010 (0.25)

0.040 (1.02) MAX

0.160 (4.06)

0.140 (3.56)

0.100 (2.54)

BSC

0.200 (5.08)

BSC

0.100 (2.54)

BSC

45° BSC

BASE & SEATING PLANE

REFERENCE PLANE

0.370 (9.40)

0.335 (8.51)

0.305 (7.75)

BOTTOM VIEW

SIDE VIEW

0.021 (0.53)

0.016 (0.40)

0.50 (12.70)

MIN

0.034 (0.86)

0.028 (0.71)

0.045 (1.14)

0.027 (0.69)

Figure 49. 8-Lead Metal Can [TO-99]

(H-08)

J-Suffix

Dimensions shown in inches and (millimeters)

Data Sheet OP27

Rev. H | Page 21 of 21

ORDERING GUIDE

Model

Temperature Range

Package Description

Package Option

OP27AJ/883C −55°C to +125°C 8-Lead Metal Can (TO-99) J-Suffix (H-08)

OP27GJZ −40°C to +85°C 8-Lead Metal Can (TO-99) J-Suffix (H-08)

OP27AZ −55°C to +125°C 8-Lead CERDIP Z-Suffix (Q-8)

OP27AZ/883C −55°C to +125°C 8-Lead CERDIP Z-Suffix (Q-8)

OP27EZ −25°C to +85°C 8-Lead CERDIP Z-Suffix (Q-8)

OP27GZ −40°C to +85°C 8-Lead CERDIP Z-Suffix (Q-8)

OP27EPZ 0°C to +70°C 8-Lead PDIP P-Suffix (N-8)

OP27GPZ −40°C to +85°C 8-Lead PDIP P-Suffix (N-8)

OP27GS −40°C to +85°C 8-Lead SOIC_N S-Suffix (R-8)

OP27GS-REEL7 −40°C to +85°C 8-Lead SOIC_N S-Suffix (R-8)

OP27GSZ −40°C to +85°C 8-Lead SOIC_N S-Suffix (R-8)

OP27GSZ-REEL −40°C to +85°C 8-Lead SOIC_N S-Suffix (R-8)

OP27GSZ-REEL7

−40°C to +85°C

8-Lead SOIC_N

S-Suffix (R-8)

OP27NBC Die

1 The OP27GJZ, OP27EPZ, OP27GPZ, OP27GSZ, OP27GSZ-REEL, and OP27GSZ-REEL7 are RoHS compliant parts.

registered trademarks are the property of their respective owners.

D00317-0-10/15(H)