One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 617/329-4700

Fax: 617/326-8703

PIN CONFIGURATION

REV. 0

Information furnished by Analog Devices is believed to be accurate and

reliable. However, no responsibility is assumed by Analog Devices for its

use, nor for any infringements of patents or other rights of third parties

which may result from its use. No license is granted by implication or

otherwise under any patent or patent rights of Analog Devices.

a

Precision, Low Cost

Dual BiFET Op Amp

AD642

PRODUCT DESCRIPTION

The AD642 is a pair of matched high speed monolithic BiFET

operational amplifier fabricated with the most advanced bipolar,

JFET and laser trimming technologies. The AD642 offers

matched bias currents that are significantly lower than currently

available monolithic dual FET input operational amplifiers:

35 pA max matched to 25 pA for the AD642K and L; 75 pA

max, matched to 35 pA for the AD642J and S. In addition, the

offset voltage is laser trimmed to less than 0.5 mV and matched

to 0.25 mV for the AD642L, 1.0 mV and matched to 0.5 mV for

the AD642K, utilizing Analog’s laser-wafer trimming (LWT)

process.

The tight matching and temperature tracking between the

operational amplifiers is achieved by ion-implanted JFETs and

laser-wafer trimming. Ion-implantation permits the fabrication of

precision, matched JFETs on a monolithic bipolar chip. The

optimizes the process to product matched bias currents which

have lower initial bias currents than other popular BiFET op

amps. Laser-wafer trimming each amplifier’s input offset voltage

assures tight initial match and combined with superior IC

processing guarantees offset voltage tracking over the tempera-

ture range.

The AD642 is recommended for applications in which excellent

ac and dc performance is required. The matched amplifiers

provide a low-cost solution for true instrumentation amplifiers,

log ratio amplifiers, and output amplifiers for four quadrant

multiplying D/A converters such as the AD7541.

The AD642 is available in four versions: the ‘‘J’’, ‘‘K’’ and ‘‘L,’’

all specified over the 0

°C to +70°C temperature range and one

version, ‘‘S,’’ over the –55

°C to +125°C extended operating

temperature range. All devices are packaged in the hermetically-

sealed, TO-99 metal can or available in chip form.

PRODUCT HIGHLIGHTS

1. The AD642 has tight matching specifications to ensure high

performance, eliminating the need to match individual

devices.

2. Analog Devices, unlike some manufacturers, specifies each

device for the maximum bias current at either input in the

warmed-up condition, thus assuring the user that the AD642

will meet its published specifications in actual use.

3. Laser-wafer-trimming reduces offset voltage to as low as

0.5 mV max and matched side to side to 0.25 mV

(AD642L), thus eliminating the need for external nulling.

4. Low voltage noise (2

µV, p-p), and high open loop gain

enhance the AD642’s performance as a precision op amp.

5. The standard dual amplifier pin out allows the AD642 to

replace lower performance duals without redesign.

6. The AD642 is available in chip form.

FEATURES

Matched Offset Voltage

Matched Offset Voltage Over Temperature

Matched Bias Current

Crosstalk: –124 dB @ 1 kHz

Low Bias Current: 35 pA max Warmed Up

Low Offset Voltage: 500

V max

Low Input Voltage Noise: 2

V p-p

High Open Loop Gain

Low Quiescent Current: 2.8 mA max

Low Total Harmonic Distortion

Standard Dual Amplifier Pin Out

Available in Hermetic Metal Can Package and Chip Form

MIL-STD-883B Processing Available

Single Version Available: AD542