The High Precision Capacitance Array in 16-bit SAR ADC

Abstract

In SAR ADC, the capacitance array is a very important unit, it will determine the conversion performance of the whole ADC. In normal semiconductor foundry, the matching precision of the linear capacitor is always about 10 bit, so it is not impossible to realize the 16-bit conversion precision in normal COMS foundry. This paper introduces a new design, for getting a smaller layout area, the main body frame of capacitor array uses the M+N+L bit sectional type; For getting the high matching precision performance, the lower bridging capacitor will be the normalized capacitor; For getting the high conversion precision, all the Upper-Bit in capacitance array will add a sub-calibrated capacitor array. So in this paper, it uses the circuit structure to realize the high precision capacitor array in 16-bit SAR ADC.