An 11 Bit Sub-Ranging SAR ADC with Input Signal Range of Twice Supply Voltage

Abstract

Analog-to-digital converters are one of the essential components in modern highly integrated Power Management ICs (PMICs). Although, the conversion time and resolution requirements are relatively easy to achieve, the requirements such as extended input signal range exceeding the system supply level, low power consumption for higher system efficiency, and resilience to heavy substrate and supply noise complicate the design of the ADC. In this paper, an 11 bit Sub-Ranging SAR analog to digital converter designed for power management systems is presented. The supply voltage and the reference voltage of the converter are both equal to 2.75 V while any of its 8 input channels can vary between 0-5.5 V range (or twice the reference voltage). The integral and differential nonlinearities of the converter are 0.38 and 0.45 LSB respectively. The ADC draws only 140 <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> A of quiescent current and has a conversion time of 10 <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> s.