An 80dB-SNDR 98dB-SFDR Noise-Shaping SAR ADC with Duty-Cycled Amplifier and Digital-Predicted Mismatch Error Shaping

Abstract

This paper presents a low-power and high-linearity noise-shaping SAR ADC that employs a duty-cycled amplifier and a mismatch error shaping technique. The power-efficient duty-cycled amplifier with 18x gain and two passive integrators provide 2nd-order noise shaping to improve in-band noise attenuation. Mismatch error shaping with a two-level digital prediction scheme is used to 1st-order shape the capacitive DAC mismatch errors without sacrificing the input signal range. The proposed ADC is fabricated in 65 nm CMOS technology and achieves 80 dB peak SNDR and 98 dB peak SFDR in a 31.25 kHz bandwidth, leading to a Schreier FoM of 176.3 dB.