Patent ID: 6459399
Filing Date: 2002-10-01
Classification: H03M

Abstract:
An analog-to-digital (A/D) converter circuit having:N (where N is a natural number above 2) comparators, each comparator receiving an input analog signal and a respective reference voltage, comparing the input analog signal to the respective reference voltage, and generating a digital signal based on comparing the input analog signal to the reference voltage; a series-connected resistor circuit having N+1 resistors connected in series, the series-connected resistor circuit having first and second terminals, wherein a node between a directly connected pair of resistors is connected to a terminal of the respective comparator that receives the reference voltage; a first buffer circuit having an output terminal to which the first of the terminals of the series-connected resistor circuit is connected; a second buffer circuit having an output terminal to which the second of the terminals of the series-connected resistor circuit is connected; a third buffer circuit having an output terminal to which terminals of the comparators that receive the input analog signal are connected; a first switch for selecting between a first voltage of a power source, and a first reference voltage for generating each reference voltage, and connecting the voltage selected to an input terminal of the first buffer circuit; a second switch for selecting between the first voltage of the power source, and a second reference voltage for generating each reference voltage, and connecting the voltage selected to an input terminal of the second buffer circuit; and a third switch for selecting between a second voltage of the power source, and the input analog signal, and connecting the voltage or input analog signal selected to an input terminal of the third buffer circuit.