A high current efficiency rail-to-rail operational amplifier

This paper proposes a new single stage high current efficiency rail to rail amplifier (HCE-RTR). Due to the combination of a new constant transconductance control circuit and local common mode feedback (LCMFB) technique, the proposed rail to rail amplifier not only achieves improvements in unity-gain bandwidth (GBW) and slew rate (SR), but also ensures input stage transconductance constancy within the rail to rail voltage range. Based on the SMIC 180 nm process, the post-layout simulation results show that the proposed amplifier achieves rail-to-rail input/output. The simulated open loop AC response shows the DC gain, GBW, and PM are 66.2 dB, 8.2 MHz, and 60.97$<^>o$ o, respectively. When the driving load capacitance is 70 pF, the transient response simulation results show that the proposed amplifier achieves 0.039 mu s average 1% settling time, and about 5.73 V/mu s average slew rate. Note that under the condition of 1.8 V power supply, the power consumption is only 122.4 mu W, proving the proposed amplifier can achieve high current efficiency while maintaining stability.