Patent ID: 7279949

Claim:
Apparatus for delaying an input signal, comprising: a reference current generator for generating a constant current, wherein the constant current is insensitive to a variation of a power supply voltage; at least one variable bias voltage generator coupled to the reference current generator for generating a set of bias voltages based on the constant current generated by the reference current generator and a digitally programmable delay control input; at least one delay element coupled to the at least one variable bias voltage generator for delaying the input signal by a constant delay which is determined by the set of bias voltages generated by the at least one variable bias voltage generator; a second variable bias voltage generator coupled to the reference current generator for generating a second set of bias voltages based on the constant current generated by the reference current generator and a second digitally programmable delay control input; and a second delay element coupled to the second variable bias voltage generator and the at least one delay element for delaying the input signal by a second constant delay which is determined by the second set of bias voltages generated by the second variable bias voltage generator.