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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 V•pF/µs•µW large-signal figure of merit (FOM) and 17 MHz • pF/µW smallsignal FOM with 1.2-V supply voltage. In subthreshold, the op-amp has 10 V • pF/µs • µW large-signal FOM and 92 MHz • pF/µW small-signal FOM with 0.5-V supply voltage. Index Terms-Analog integrated circuits, class AB-AB Miller op-amps, Miller compensation, resistive local common mode feedback. I. INTRODUCTIONT HE increasing demand for battery-operated portable electronics equipment requires power-efficient analog circuits. The operational amplifier (op-amp) is the essential building block of analog signal processing units [1], [2]. Due to the reduction of the supply voltage in deep submicrometer mixed-signal design, the op-amp may suffer from slew rate limitation, insufficient bandwidth, lower gain, reduced dynamic range, inadequate noise performance, and linearity problems [3]. Hence, the energy-efficient high-speed

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A fully differential Miller op-amp with a composite input stage using resistive local commonmode feedback and regulated cascode transistors is presented here. High gain pseudo-differential auxiliary amplifiers are used to implement the regulated cascode transistors in order to boost the output impedance of the composite input stage and the open-loop gain of the op-amp. Both input and output stages operate in class AB mode. The proposed op-amp has been simulated in a 130nm commercial CMOS process technology. It operates from a 1.2V supply and has a close to rail-to-rail differential output swing. It has 156dB DC openloop gain and 63MHz gain-bandwidth product with a 30pF capacitive load. The op-amp has a DC open-loop gain figure of merit FOM AOLDC of 174 (MV/V) MHz pF/µW and large-signal figure of merit FOM LS of 3(V/µs) pF/µW.