Bipolar rail-to-rail constant- g m input stagefor low voltage applications

A new bipolar rail-to-rail input stage for low voltage operational amplifiers is presented. This simple circuit features a virtually constant transconductance against input common mode voltage, in the 0–100°C temperature range, and can operate at a supply voltage as low as 0.85 V. A circuit description is given, and some SPICE simulation results are reported, which demonstrate the effectiveness of the proposed technique.