Patent ID: 6570402
Filing Date: 2003-05-27
Classification: G05F,H03M

Abstract:
An impedance control circuit comprising:a current source for providing a substantially constant current; an impedance adjustment circuit connected to the current source, for adjusting the current fed by the current source in response to a plurality of second control signals and to output an output signal at a target voltage; a comparator for comparing a reference voltage with the target voltage and outputting a compared signal; a thermal code generator for receiving the compared signal and a clock signal and outputting a plurality of first control signals corresponding to the compared signal in response to the clock signal; a control circuit for receiving the compared signal and the clock signal and counting the number of logic value transitions of the compared signal and for generating a complete signal in response to the clock signal to stop operating the comparator if a predetermined condition is met; and a register for latching the first control signals in response to the complete signal and generating the second control signals.