A 10-mW 16-b 15-MS/s Two-Step SAR ADC With 95-dB DR Using Dual-Deadzone Ring Amplifier

Low-noise ring amplifiers required for high-precision analog-digital converters (ADCs) greater than 16 b remain unexplored. This article demonstrates a two-step successive approximation (SAR) ADC achieving 91-dB signal-to-noise-and-distortion-ratio (SNDR) with 6-V differential input resulting in a low-frequency Schreier-figure-of-merit (FOMS,lf ) of 179.8 dB at 15 MS/s. The state-of-the-art performance is enabled by the ring-amplifier design that enables low noise during amplification and robust control of the transient dynamics. The ADC also features an on-chip residue amplifier (RA) settling characterization using the backend SAR ADC. The ADC is fabricated in a 180-nm CMOS process and occupies an active area of 1.82 mm².