Patent ID: 6642873
Filing Date: 2003-11-04
Classification: H03M

Abstract:
A multi-bit sigma-delta analog-to-digital (A/D) converter, comprising:a summer having a first input for analog input signals and a second input for analog feedback signals; a loop filter of filtering the summed signals supplied by the output of said summer; N comparators configured in parallel, each of said N comparators having a first input and a second input, said N comparators outputting digital thermometer code, where N is an integer greater than one; a switch having single pole and N throws, in which said single pole can be connected to each of said N throws by digital control, said single pole being externally connected to said second input of said summer in negative sense; a voltage divider network of dividing a voltage reference signal into various voltage levels, which are applied to said N second inputs of said N comparators and to said N throws of said switch; a switching control logic unit that transforms said digital thermometer code supplied by said N comparators into digital control signals used to control said switch; an encoder that transforms said digital thermometer code supplied by said N comparators into binary code; and a digital decimation filter in connection with said encoder.