The Theory And Circuit Realization Of Digital Calibration For Pipelined A/D Converter

Recently, with the development of video and communication technique, high-speed and high-precision A/D converters are needed more and more. As a very important circuit construction, pipelined A/D has these merits, so it is used widely. Digital correction technique is one of key methods for improving performance of pipelined A/D converter, being studied a lot in both school and industry. Two kinds of digital correction methods are studied in detail. Simulation results are proved right for these algorithms.Based on the analysis of the reasons of the pipeline A/D converter why the error and other effects are bringed, the paper gives a kind of ways for correcting these nonideal factors that are gain errors, comparator offset and capacity mismatch. Correction methods for gain errors are studied. Digital frontend method is a good way but it has to interrupt the flow of converter. Digital backend correction method is put forward and it can work independently. Comparator offset has very bad effection on the precision of A/D converter. Digital correction principle is introduced and some usual ways to reduce the offset are mentioned. For correcting capacity mismatch, capacity error equilibration technique is introduced and another way of digital methods is bringed.This paper is emphasis on the study of redundancy digital correction technique. It is proved right by using HSPICE based on SMIC 0.35μm CMOS technology. To make use of this method, offset error can be reduced greatly.A new method is researched based on random signal error correction. SIMULINK simulation results show that this way can improve performance of pipelined A/D converter remarkably.The methods that this paper proposes are all digital calibration algorithms and they are realized in digital integrated circuits. With these ways the require of analog circuit can be reduced and pipelind A/D converter can have a good performance.