Modeling and Design of A Compact Low Power Folded Cascode OpAmp With High EMI Immunity

In this letter, the modeling and design of a low-power, compact folded cascode operational amplifier with high immunity to electromagnetic interference (EMI) is presented. The insights derived from the modeling of parameters $V_{gsi}$, $V_{sbi}$, and $V_{dsi}$ of the first-stage folded cascode OpAmp with channel length modulation are employed in designing the proposed compact folded cascode OpAmp with 23% reduction in power and 10% reduction in area when compared to the robust folded cascode OpAmp. In addition, a comprehensive comparison of the proposed compact folded cascode OpAmp, classical folded cascode OpAmp, and the robust folded cascode OpAmp is presented when each of these OpAmps are subjected to an EMI of 1.7 Vpp. The postlayout simulation results show that the maximum EMI-induced output offset voltage for the compact folded cascode OpAmp is 6.6 mV over a wide range of frequencies from 1 MHz to 1 GHz by keeping the main specifications intact as that of a robust folded cascode OpAmp.