A 1-1-1-1 MASH delta-sigma modulator using dynamic comparator-based OTAs

A 1-1-1-1 MASH delta-sigma modulator with dynamic comparator-based OTAs as replacements for conventional OTAs is presented. The proposed OTA asynchronously alternates between input comparison and current pulse injection under digital control. The 65-nm LP CMOS prototype achieves a FoM of 276 fJ/conv-step with 70.4 dB SNDR over a 2.5-MHz bandwidth while consuming 3.73 mW from a 1.2-V supply.