OPERATIONAL AMPLIFIER

OPA128

Noise-Free

Cascode

Ω

1k

Trim

1

5

3

2

+In

–In

Case (Guard)

Output

OPA128 Simplified Circuit

+V

CC

8

7

6

4

28k

Ω

Ω

1k

2k

Ω

2k

Ω

Trim

28k

Ω

FEATURES

q ULTRA-LOW BIAS CURRENT: 75fA max

q LOW OFFSET: 500

µV max

q LOW DRIFT: 5

µV/

q HIGH OPEN-LOOP GAIN: 110dB min

q HIGH COMMON-MODE REJECTION:

90dB min

q IMPROVED REPLACEMENT FOR AD515

AND AD549

DESCRIPTION

The OPA128 is an ultra-low bias current monolithic

operational amplifier. Using advanced geometry

lithic amplifier achieves a performance level exceed-

ing even the best hybrid electrometer amplifiers.

Laser-trimmed thin-film resistors give outstanding volt-

age offset and drift performance.

A noise-free cascode and low-noise processing give

the OPA128 excellent low-level signal handling capa-

bilities. Flicker noise is very low.

The OPA128 is an improved pin-for-pin replacement

for the AD515.

APPLICATIONS

q ELECTROMETER

q MASS SPECTROMETER

q CHROMATOGRAPH

q ION GAUGE

q PHOTODETECTOR

q RADIATION-HARD EQUIPMENT

PDS-653E

Printed in U.S.A. May, 1995

®

International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: (520) 746-1111 • Twx: 910-952-1111

Internet: http://www.burr-brown.com/ • FAXLine: (800) 548-6133 (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132

SBOS148