A PVT-robust Gm-R-based residue amplifier with folded positive feedback technique

Abstract

This paper presents a process, voltage and temperature (PVT) robust Gm-R-based residue amplifier (RA). The proposed folded positive feedback (FPF) technique facilitates a high open-loop gain of 49.2 dB and gain bandwidth of 30.6 GHz without employing multiple cascading stages or cascode devices, consuming only 8.2 mW. The PVT robustness of the proposed RA is self-adapted, addressing the requirement of bias-generating circuitry. Transistor level design and simulations are implemented based on a 28 nm CMOS process. Configured in closed-loop, the proposed RA demonstrates a relative gain variation smaller than 5% and a fast settling time of 400 ps. The simulated gain linearity exceeds 9 bit with a 440 m$V_{pp}$ output swing, yielding an improved trade-off between speed and accuracy in nanoscale RA designs.