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

Abstract

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/ $\mu \text{W}$ .

Keywords

• Class-AB op-amp
• fully differential amplifier
• Miller-compensation
• regulated cascode
• resistive local common-mode feedback
• voltage follower