Super-Gain-Boosted AB-AB Fully Differential Miller Op-Amp With 156dB Open-Loop Gain and 174MV/V MHZ pF/μW Figure of Merit in 130nm CMOS Technology

A fully differential Miller op-amp with a composite input stage using resistive local common-mode 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 open-loop 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/
$\mu \text{W}$
and large-signal figure of merit
$FOM_{LS} $
of 3(V/
$\mu \text{s}$
) pF/
$\mu \text{W}$
.