使用MOS电容的循环型ADC的数字校正技术

A Digital Calibration Technique for Cyclic Analog-to-Digital Converters Using MOS Capacitors

一种用于循环型模拟-数字转换器的新型数字校正技术,循环型模拟-数字转换器(ADC)使用了金属-氧化物-半导体场效应晶体管(MOS)电容,这种电容具有很大的电压-电容依赖性。使用MOS电容的循环型ADC具有较大的积分非线性(INL),但是同时具有很小的微分非线性(DNL)。用降低INL的数字校正算法,降低硬件实现的难度,还提出了一种简化的校正算法,同时保持了足够低的INL+1.25/-0.25 LSB。讨论了其他一些误差源的影响,包括电容失配,运算放大器的有限增益和比较器失调。

This paper presents a digital calibration technique to a cyclic analog-to-digital converter （cyclic ADC） using MOS capacitors （MOSCAPs） which has a large applied voltage dependency but a high capacitance per area. The cyclic ADC with MOSCAPs has a large integral nonlinearity （INL） , but a very small differential nonlinearity （DNL）. A digital calibration algorithm is presentedtoreducethe INL. A simplified algorithm is presented toreduce hardware implementation, and still has sufficient small INL of ＋ 1. 25/- 0. 25 LSB. The influences of other error sources including capacitor mismatch, amplifier finite gain and comparator offset arealso discussed.