The AD704 is a quad, low power bipolar op amp that has the low input bias current of a BiFET amplifier and offers a signifi-cantly lower I_B 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 use in low frequency active filters in 12- and 14-bit data acquisition systems, in precision instrumentation, and as a high quality integrator. The AD704 is internally compensated for unity gain stability. The AD704J is rated over the commercial temperature range of 0°C to 70°C. The AD704A is rated over the industrial temperature of −40°C to +85°C. The AD704S is rated over the military temperature range of −55°C to +125°C, processed to MIL-STD-883B.

Applications

• Industrial/process controls
• Weigh scales
• ECG/EKG instrumentation
• Low frequency active filters

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.