A 10-bit 50-MS/s SAR ADC with techniques for relaxing the requirement on driving capability of reference voltage buffers

Abstract

A high speed successive approximation (SAR) ADC requires reference voltage buffers with high driving capability. Moreover, the power consumption of the reference buffers is usually several times larger than that of the SAR ADC itself. Three techniques are adopted to mitigate the requirement on driving capability of reference voltage buffers for SAR ADCs. A 10b 50MS/s ADC based on the proposed techniques is presented. The prototype ADC was fabricated in 40nm LP 1P7M CMOS technology. It consumes 0.47 mW at 50 MS/s from 1.1V supply voltage and achieves ENOB of 9.18-bit and figure of merit (FoM) of 16 fJ/conversion-step. The active area is 0.0114 mm2.