PRODUCT DESCRIPTION
The AD644 is a pair of matched high speed monolithic FET input operational amplifiers fabricated with the most advanced bipolar, JFET and laser-trimming technologies. The AD644 offers matched bias currents that are significantly lower than currently available monolithic dual BiFET operational amplifiers: 35 pA max, matched to 25 pA for the AD644K and L, 75 pA max matched to 35 pA for the AD644J and S. In addition, the offset voltage is laser trimmed to less than 0.5 mV, and matched to 0.25 mV for the AD644L, 1.0 mV and matched to 0.5 mV for the AD644K, utilizing Analog Devices’ 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. This process optimizes the ability to produce matched amplifiers 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 superior IC processing guarantees offset voltage tracking over the temperature range.
The AD644 is recommended for applications in which both excellent ac and dc performance is required. The matched amplifiers provide a low cost solution to true wideband instrumentation amplifiers, low dc drift active filters and output amplifiers for four quadrant multiplying D/A converters such as the AD7541, 12-bit CMOS DAC.

FEATURES
   Matched Offset Voltage
   Matched Offset Voltage Over Temperature
   Matched Bias Currents
   Crosstalk –124 dB at 1 kHz
   Low Bias Current: 35 pA max Warmed Up
   Low Offset Voltage: 500 mV max
   Low Input Voltage Noise: 2 mV p-p
   High Slew Rate: 13 V/ms
   Low Quiescent Current: 4.5 mA max
   Fast Settling to 60.01%: 3 ms
   Low Total Harmonic Distortion: 0.0015% at 1 kHz
   Standard Dual Amplifier Pinout
   Available in Hermetic Metal Can Package
      and Chip Form
   MIL-STD-883B Processing Available
   Single Version Available: AD544