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

A rail-to-rail operational amplifier in 0.6 μm 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 ± 0.75 V, the proposed rail-to-rail operational amplifier achieves 70 dB DC open-loop gain, 2.36 MHz unity gain frequency, 64° phase margin, 2.3 V/μs slew rate, and 146 μW power consumption.