A Dual-Mode Successive-Approximation-Register Analog-to-Digital Converter for Biomedical Application

Abstract

This thesis presents a successive-approximation-register analog-to-digital converter (SAR ADC) which can measure voltage and current By the techniques of exchanging capacitor arrays and multi-sampling SAR ADC is enabled to sense current Therefore a dual-mode SAR ADC for biomedical application is achieved Because of biomedical application power consumption is critical for the proposed circuit Consequently supply voltage of the proposed circuit is reduced to 0 5 V and split capacitor array and differential control logic are adopted in the proposed circuit to reduce power consumption Besides double-bootstrapped technique and stacked-transistor technique are used in switches to enhance conductivity and solve leakage problem The proposed dual-mode SAR ADC is implemented by TSMC 0 18-μm 1P6M CMOS process According to simulation results the peak SNDR is 60 dB with sampling frequency of 20 kHz in voltage mode The power consumption is 63 44 nW and the Figure-of-Merit (FoM) is 3 88 fJ/conversion In current mode the sensitivity of 1 18 pA is achieved with sampling frequency of 1 kHz The measurement results shows that the peak SNDR is 51 95 dB with sampling frequency of 20 kHz in voltage mode The power consumption is 64 46 nW and the Figure-of-Merit (FoM) is 9 94 fJ/conversion

Date of Award	2015 Jan 12
Original language	English
Supervisor	Bin-Da Liu (Supervisor)