AD704

00818-002 Picoampere Input Current Quad Bipolar Op Amp AD704 FEATURES High dc precision 150 µV maximum offset voltage 1.5 µV/°C maximum offset voltage drift 270 pA maximum input bias current 0.3 pA/°C typical IB drift Low noise: 0.5 µV p-p Typical noise: 0.1 Hz to 10 Hz Low power: 600 µA maximum supply current per amplifier Dual version: AD706 APPLICATIONS Industrial/process controls Weigh scales ECG/EKG instrumentation Low frequency active filters GENERAL DESCRIPTION The AD704 is a quad, low power bipolar op amp that has the low input bias current of a BiFET amplifier and offers a significantly lower IB drift over temperature. It uses superbeta bipolar input transistors to achieve picoampere input bias current levels (similar to FET input amplifiers at room temperature), while its IB typically increases only by 5× at 125°C (unlike a BiFET amp, for which IB doubles every 10°C, resulting in a 1000× increase at 125°C). In addition, the AD704 achieves 150 μV offset voltage and the low noise characteristics of a precision bipolar input op amp. Because it has only 1/20 the input bias current of an OP07, the AD704 does not require the commonly used balancing resistor. Furthermore, the current noise is 1/5 that of the OP07, which makes the AD704 usable with much higher source impedances. At 1/6 the supply current (per amplifier) of the OP07, the AD704 is better suited for today’s higher density circuit boards and battery-powered applications. The AD704 is an excellent choice for u...