OPA129
OPA
129
OPA
129
SBOS026A – JANUARY 1994 – REVISED APRIL 2007
Ultra-Low Bias Current
Difet
®
OPERATIONAL AMPLIFIER
FEATURES
q
ULTRA-LOW BIAS CURRENT: 100fA max
q
LOW OFFSET: 2mV max
q
LOW DRIFT: 10
µ
V/
°
C max
q
HIGH OPEN-LOOP GAIN: 94dB min
q
LOW NOISE: 15nV/
√
Hz at 10kHz
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
Substrate
8
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 (
Difet
®
) inputs, this monolithic
amplifier achieves a high performance level.
7
V+
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
2
3
+In
Noise-Free
Cascode
6
Output
30kΩ
30kΩ
5
V–
Simplified Circuit
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.
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
www.ti.com
TI [ TEXAS INSTRUMENTS ]
