A Low Power Constant-Gm Rail-to-Rail Operational Transconductance Amplifier by Recycling Current

A modification to the conventional constant-g(m) rail to-rail operational transconductance amplifier is presented. The proposed amplifier has the benefit of delivering the same performance while consuming a fraction of the power compared to the conventional rail-to-rail amplifier. This is achieved by recycling the bias current of idle devices,which results in an enhanced transconductance, gain and slew rate. The proposed amplifier was implemented in SMIC standard 65 nm CMOS process. Simulation results show that the proposed amplifier achieves 168.1 MHz unity-gain bandwidth, 63.8 dBDC gain, 23.4V/us slew rate and less than 8% deviation in transconductance, but the power consumption reduced by 50% compared to the conventional rail-to-rail amplifier with the same design specifications.