GENERAL DESCRIPTION

The AD706 is a dual, low power, bipolar op amp that has the low input bias current of a JFET amplifier, but which offers a significantly lower I drift over temperature. It utilizes superbeta bipolar input transistors to achieve picoampere input bias current

levels (similar to FET input amplifiers at room temperature), while its IB typically only increases by 5 at 125°C (unlike a JFET amp, for which IB doubles every 10°C for a 1000 increase at 125°C). The AD706 also achieves the microvolt offset voltage and low noise characteristics of a precision bipolar input amplifier.

Since it has < 200 pA of bias current, the AD706 does not require the commonly used “balancing” resistor. Furthermore, the current noise is only 50 fA/√Hz, which makes this amplifier usable with very high source impedances. At 600 A max supply current (per amplifier), the AD706 is well suited for today’s high density boards.

The AD706 is an excellent choice for use in low frequency active filters in 12-bit and 14-bit data acquisition systems, in precision instrumentation, and as a high quality integrator. The AD706 is internally compensated for unity gain and is available in five performance grades. The AD706J is rated over the commercial temperature range of 0°C to +70°C. The AD706A is rated for the extended industrial temperature range of –40°C to +85°C.

The AD706 is offered in two varieties of an 8-lead package: PDIP and surface-mount (SOIC).