Untrimmed 12 bit monotonic all capacitive A to D converter

摘要

An M-bit all-capacitive analog-to-digital (A/D) converter is disclosed which includes 2N switched capacitors of substantially identical capacitance for use in determining the N most significant bits. Each of the capacitors have one terminal connected to a common node and its other terminal switchable to either ground or a positive reference voltage. At the beginning of a conversion cycle, the common node is at a potential indicative of a sampled analog input voltage, a first group of 2N-1 capacitors are switched to ground, and a second group of 2N-1 capacitors are switched to the positive reference voltage. For a given conversion cycle, selected capacitors of one of the capacitor groups are sequentially switched to drive the common node voltage to ground. A method is also disclosed for converting analog signals to digital signals utilizing parallel capacitive elements of substantially identical capacitance.