Ultra-Low Bias Current

OPERATIONAL AMPLIFIER

FEATURES

q ULTRA-LOW BIAS CURRENT: 100fA max

q LOW OFFSET: 2mV max

q LOW DRIFT: 10

q HIGH OPEN-LOOP GAIN: 94dB min

q LOW NOISE: 15nV/

q PLASTIC DIP AND SO PACKAGES

APPLICATIONS

q PHOTODETECTOR PREAMPS

q CHROMATOGRAPHY

q ELECTROMETER AMPLIFIERS

q MASS SPECTROMETERS

q pH PROBE AMPLIFIERS

q ION GAGE MEASUREMENT

DESCRIPTION

The OPA129 is an ultra-low bias current monolithic

operational amplifier offered in an 8-pin PDIP and

SO-8

package.

Using

advanced

geometry

dielectrically-isolated FET (

amplifier achieves a high performance level.

Difet fabrication eliminates isolation-junction leakage

current—the main contributor to input bias current with

conventional monolithic FETs. This reduces

input bias current by a factor of 10 to 100. Very low

input bias current can be achieved without resorting to

small-geometry FETs or CMOS designs which can

suffer from much larger offset voltage, voltage noise,

drift, and poor power-supply rejection.

The OPA129 special pinout eliminates leakage current

that occurs with other op amps. Pins 1 and 4 have no

internal connection, allowing circuit board guard traces—

even with the surface-mount package version.

OPA129 is available in 8-pin DIP and SO packages,

specified for operation from –40

°C to +85°C.

+In

Output

6

Noise-Free

Cascode

7

5

V–

V+

30k

Ω

30k

Ω

–In

3

2

Simplified Circuit

8

Substrate

OPA

129

OPA129

OPA129

SBOS026A – JANUARY 1994 – REVISED APRIL 2007

www.ti.com

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

Copyright © 1994–2007, Texas Instruments Incorporated

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

Difet is a registered trademark of Texas Instruments.

All other trademarks are the property of their respective owners.