Adaptive digital noise-cancellation filtering using cross-correlators for continuous-time MASH ADC in 28nm CMOS

This paper presents an adaptive digital noise cancellation filter (DNCF) using cross-correlation (XCORR) developed for continuous-time (CT) multi-stage noise-shaping (MASH) ADCs. The XCORR engine continuously estimates the transfer functions of ΔΣ sub-loops and updates the coefficients for the DNCF. An ADC prototype with this engine is built in 28nm CMOS and it achieves 72dB of dynamic range over 440MHz BW, with a total power of 1.25W from 1V and 1.8V supplies. Comparing to a power-up least-mean squares (LMS) engine, the XCORR-based adaptive DNCF achieves 2dB better noise cancellation across up to 10% supply variations.