Input adapter based BiCMOS operational amplifier with rail-to-rail capability

A rail-to-rail operational amplifier in 0.6 mum BiCMOS technology is presented. Two simple input signal adapters with floating outputs are introduced. They translate the input signals into the operating region of the differential amplifier, enabling rail-to-rail operation. An inverter-based rail-to-rail class AB output stage was used. With a bipolar supply of plusmn 0.75 V, the proposed rail-to-rail operational amplifier achieves 70 dB DC open-loop gain, 2.36 MHz unity gain frequency, 64deg phase margin, 2.3 V/mus slew rate, and 146 muW power consumption.