A 65.5-dB SNDR 100-MS/s Pipelined-SAR ADC With Nested Negative-C and Dynamic Auto-Zeroing Residue Amplifier Achieving ≤ 2.2-dB ΔSNDR Over −20 °C to 125 °C

This paper demonstrates a 12-bit 100-MS/s PVT-stabilized pipelined-SAR ADC with fully integrated on-chip calibration. Two key innovations facilitate over 65-dB SNDR with less than 2.2-dB variation from -20 °C to 125 °C: First, a PVT-stabilized nested negative-C topology boosts open-loop gain (Gₒₗ) of the residue amplifier (RA) by 28 dB, enabling one-time foreground calibration that avoids persistent inter-stage gain error tracking. Second, a dynamic auto-zeroing technique addresses offsets from both the RA and first-stage comparator through a switched-capacitor filter that extracts offsets based on the stochastic characteristics of residue signals. Dynamically level-shifted capacitors (DLSC) are embedded at the differential inputs to neutralize aliased noise and thermal noise, so that the offset drifts under high-temperature environment are effectively cancelled. Fabricated in 40-nm CMOS, the prototype occupies 0.22 mm2and achieves 65.5-dB SNDR and 83-dB SFDR at Nyquist input while consuming 3.7 mW. Across six tested chips, the prototype design exhibits merely 2.2-dB SNDR degradation over -20 °C ~ 125 °C and 1.3-dB variation under ± 5 % supply voltage (1.1 V) fluctuations.