An Energy-efficient switching 10bit SAR ADC for biomedical application

Abstract

This paper presents a Successive-Approximation Rgister Analog-to-Digital Converter (SAR ADC) for biomedical applications. Among them, the ADC built into the implantable cardioverter-defibrillator(ICDs) is a battery-powered sensor, so low-power design is the main goal. Since DAC switching energy of each conversion is dominant in the power consumption of the SAR ADC, an improved switching scheme is required. The proposed switching presents a method of reducing switching energy for slow signals in the ECG excluding the QRS interval. Using the time information of the comparator, MSB and MSB-1 are determined simultaneously, switching is skipped, and as a result, compared to the existing method, significantly reduced average switching energy can be obtained numerically. This ADC has been designed with 0.18um general logic process by MagnaChip, and idea verification is performed with Matlab, circuit implementation and design simulation are performed with Cadence Virtuoso Spectre.