A 6 mW 325 MS/s 8 bit SAR ADC with background offset calibration

Abstract

A 8-b single-channel successive approximation register (SAR) analog-to-digtial converter (ADC) fabricated in 55 nm CMOS is proposed. With segmented prequantize and bypass digital-to-analog converter (DAC), the unnecessary switching of high weight capacitors are avoided. Two alternating comparators are ultilized to reset the comparators completely without the sacrifice of conversion speed. A novel simple and low power background offset calibration technique is implemented. Operating at 325 MS/s, this ADC consumes 6 mW from 1.2 V supply, achieves SNDR of 43.6 dB and SFDR of 59.1 dB with 11-MHz input while occuping 0.011 mm².