A 72.9-dB SNDR 20-MHz BW 2-2 discrete-time sturdy MASH delta-sigma modulator using source-follower-based integrators

This paper presents a 2-2 discrete-time sturdy multi-stage noise-shaping (SMASH) delta-sigma modulator using source-follower-based open-loop integrators. The resolution of the SMASH delta-sigma modulator is enhanced by eliminating the first-stage quantization noise from the output. Using the proposed source-follower-based open-loop integrator, the operating speed of the modulator is efficiently improved. The prototype deltasigma modulator fabricated in a 65-nm CMOS process achieves a 75.8-dB dynamic range and 72.9-dB SNDR in a 20-MHz bandwidth. The modulator occupies an active area of 0.34 mm
²
, and its total power consumption is 20.4 mW from a 1.2-V supply voltage operating at a 500-MHz clock frequency.