A 55μW 93.1dB-DR 20kHz-BW single-bit CT ΔΣ modulator with negative R-assisted integrator achieving 178.7dB FoM in 65nm CMOS

Abstract

This paper presents a 3rd order single-bit CT ΔΣ modulator with active-RC integrators using negative-R assistant at virtual ground, which mitigates opamp's requirements including the thermal noise and linearity leading to a drastic power-saving. Fabricated in a 65nm CMOS process, the modulator occupies area of 0.27mm2. It achieves 100.5dB SFDR and 93.1dB DR in 20kHz BW, while consuming only 55μW from a 1.2V supply. This results in Schreier FoM of 178.7dB and Walden FoM of 63.1fJ/step.