A Stochastic Flash Analog-to-Digital Converter Linearized by Reference Swapping

Abstract

The linearity of a stochastic flash analog-to-digital converter (ADC) with two groups of comparators is improved by reference swapping. If the input offset of a comparator is larger than the linear input range of its comparator group, the reference voltage of the comparator is swapped with the reference voltage of the other comparator group. The reference swapping doubles the number of comparators providing a meaningful result in determining the ADC output. A stochastic flash ADC linearized by the reference swapping has been implemented in a 65-nm CMOS process. The peak signal-to-noise + distortion ratio is 39 dB, which is 3-dB higher than that without the reference swapping.