Pseudo-Three-Stage Miller Op-Amp With Enhanced Small-Signal and Large-Signal Performance

A simple technique to implement highly power efficient class AB-AB Miller op-amps is presented in this paper. It uses a composite input stage with resistive local common mode feedback that provides class AB operation to the input stage and essentially enhances the op-amp's effective transconductance gain, the dc open-loop gain, the gain-bandwidth product, and slew rate with just moderate increase in power dissipation. The experimental results of op-amps in strong inversion and subthreshold fabricated in a 130-nm standard CMOS technology validate the proposed approach. The op-amp has 9~\text {V} \cdot \text {pF}/\mu \text {s}\cdot \mu \text{W} large-signal figure of merit (FOM) and 17~\text {MHz}\cdot \text {pF}/\mu \text{W} small-signal FOM with 1.2-V supply voltage. In subthreshold, the op-amp has 10~\text {V}\cdot \text {pF}/\mu \text {s}\cdot \mu \text{W} large-signal FOM and 92~\text {MHz}\cdot \text {pF}/\mu \text{W} small-signal FOM with 0.5-V supply voltage.