A Novel Gain Enhanced Folded Cascode OPAMP in 28nm CMOS Technology

Folded cascade Opamp is the preferred first stage choice in a typical two-stage opamp due to relaxed headroom and better output swing. Traditional Folded cascade opamp gain and noise are compromised due to the folding transistors. In this work, FVF assisted differential pair has been proposed which extracts the signal and injects it onto the gate of the folding devices, hence they will contribute gain and noise will be reduced. A prototype was developed in 2Snm TSMC CMOS technology and post-layout simulation results were performed. The proposed opamp achieves 68dB DC gain, which is 18dB higher than the conventional one. Also, the proposal exhibits 20% improvement in the input-referred noise for the same power consumption. Further, the circuit consumes 33$\mu$W of power from a 1V power supply and occupies a 78*46$\mu$m2 silicon area.