Design of Low Power 12-bit SAR Analog-to-digital Converter

Abstract

In this paper, we present a 12-bit SAR (Successive-Approximation-Register) ADC (Analog-to-Digital Converter). The proposed ADC comprises sample-and-hold, capacitor array network, SAR control logic, comparator, DAC (Digital-to-Analog Converter) control logic, and DAC stages. This SAR ADC employs a method of changing the total capacitor capacity by adding a split capacitor to the capacitor array network, because area of the capacitor and the capacitor array network increase with the increase in resolution. A sample-and-hold circuit combined with a bootstrip technique can reduce distortion and unnecessary power consumption, as this circuit is designed to operate with a single input clock. To optimize power consumption and chip area, a 1MSps sampling rate with 12-bit resolution was designed. The proposed ADC was designed using the 1poly-6 metal 0.13㎛ CMOS process, and it operates at 1.2V. A SNDR (Signal-to-Noise Distortion Ratio) and an ENOB (Effective Number of Bits) of approximately 80.09㏈ and 11.86bits, respectively ware achieved. Compared with previous research results, the effective small chip area is approximately 0.028mm2 and the low power consumption is 63.07㎼.