An energy-efficient 16 MS/s 10-bit SAR ADC with MSB-block switching scheme

Abstract

An energy-efficient MSB-block switching scheme without common-mode voltage variation for successive approximation register (SAR) analog-to-digital converters (ADCs) is proposed. Benefit from a pair of extra switches embedded in the capacitive digital-to-analog converter (CDAC), the proposed MSB-block switching scheme can reduce switching energy without further reducing the capacitor unit. The proposed switching scheme can achieve 93.8 % and 49.9 % savings in switching energy compared with the conventional switching scheme and the Vcm-based switching scheme, and the simulated differential-nonlinearity (DNL) and integrated-nonlinearity (INL) are 0.160 and 0.156LSB, respectively. The proposed switching scheme is verified in a 1.2-V 10-bit 16 MS/s SAR ADC in 65 nm CMOS technology. At maximum sampling rate, the proposed SAR ADC achieves an effective number of bits (ENOB) of 9.50 and a power consumption of $103.5\mu W$, leading to a Figure of Merit of 8.93 fJ/Conversion-step.