®
OPA128
Difet
®
Electrometer-Grade
OPERATIONAL AMPLIFIER
FEATURES
q
ULTRA-LOW BIAS CURRENT: 75fA max
q
LOW OFFSET: 500µV max
q
LOW DRIFT: 5µV/
°
C max
q
HIGH OPEN-LOOP GAIN: 110dB min
q
HIGH COMMON-MODE REJECTION:
90dB min
q
IMPROVED REPLACEMENT FOR AD515
AND AD549
APPLICATIONS
q
ELECTROMETER
q
MASS SPECTROMETER
q
CHROMATOGRAPH
q
ION GAUGE
q
PHOTODETECTOR
q
RADIATION-HARD EQUIPMENT
DESCRIPTION
The OPA128 is an ultra-low bias current monolithic
operational amplifier. Using advanced geometry
dielectrically-isolated FET (
Difet
®
) inputs, this mono-
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.
Difet
Burr-Brown Corp.
5
Trim
1k
Ω
2kΩ
2kΩ
4
–V
CC
OPA128 Simplified Circuit
®
Case (Guard)
8
7
+V
CC
–In
2
3
+In
Noise-Free
Cascode
6
Output
Trim
1
1k
Ω
28kΩ
28kΩ
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
©
1986 Burr-Brown Corporation
PDS-653E
Printed in U.S.A. May, 1995
SBOS148
BURR-BROWN [ BURR-BROWN CORPORATION ]
