Design of resource sharing reconfigurable ΔΣ SAR-ADC

This paper presents an ADC with re-configurability between SAR-only mode and delta-sigma (ΔΣ assisted mode). The ΔΣ assisted mode brings resolution enhancement. Proposed ADC shares a capacitor array for SAR, feedback DAC, and integrator capacitor in ΔΣ loop, which can reduce the circuit size. The prototype ADC fabricated in 65-nm CMOS achieved SNDR of 44.35 dB at 32 MS/s and power consumption of 0.55 mW. The SNDR is improved to 62.9 dB by ΔΣ assisted mode.