Patent ID: 6480134
Filing Date: 2002-11-12
Classification: H03M

Abstract:
An analog-to-digital (AD) converter comprising:a reference voltage generating circuit for dividing a voltage between a first and a second reference potential to thereby generate a plurality of low reference voltages of a low level, a plurality of high reference voltages of a high level, and a plurality of medium reference voltages of a medium level; a first voltage comparator supplied with a lower one of the plurality of medium reference voltages for comparing the lower medium reference voltage with an analog voltage input to said AD converter and outputting a first control signal if the analog voltage is higher than the lower medium reference voltage; a second voltage comparator supplied with a higher one of the plurality of medium reference voltages for comparing the higher medium reference voltage with the analog voltage and outputting a second control signal independently of the first control signal if the analog voltage is lower than the higher medium reference voltage; a plurality of low reference voltage comparators each for comparing, in response to the second control signal, a particular one of the plurality of low reference voltages with the analog voltage; a plurality of medium reference voltage comparators each for comparing a particular one of the plurality of medium voltages with the analog voltage; a plurality of high reference voltage comparators each for comparing, in response to the first control signal, a particular one of the plurality of high reference voltages with the analog voltage; and a data outputting circuit for generating and outputting digital data corresponding to the analog voltage on the basis of results of comparison output from said low reference voltage comparators, said medium reference voltage comparators, and said high reference voltage comparators.