ANALOG-TO-DIGITAL CONVERTER

摘要

PURPOSE:To improve the conversion speed with high accurcy, by providing a local DA converter. CONSTITUTION:A code where an input analog signal from a terminal 11 held at a sample holding circuit 20 and an output of a local DA converter 14 are coincident with, is generated from a comparator 15 and a sequential approxiamtion register (SAR)13 through sequential comparison. A shift code generating circuit 16 is driven with the code of an high-order corresponding to the low-order DA converter input of the local DA converter 14 out of codes obtained from the sequential comparison to generate a shift amount determined in advance and this shift amount is substracted from the code from the SAR13 obtained at the sequential comparison at a code shift circuit 21, allowing to obtain a correct output code and output from a terminal 12.