Patent ID: 7088129

Claim:
A variable impedance network for variably adjusting the output impedance of a node of a circuit, comprising: one or more impedance legs electrically connected between a voltage source and said node; a first set of switchable impedance legs programmably electrically connectable between said voltage source and said node by a first set of calibration signals each of which corresponds to a respective one or more of said switchable impedance legs in said first set of switchable impedance legs; a second set of switchable impedance legs programmably electrically connectable between said voltage source and said node by a second set of calibration signals each of which corresponds to a respective one or more of said switchable impedance legs in said second set of switchable impedance legs; and a controller which generates said first set of calibration signals and said second set of calibration signals, wherein said controller steps said first set of calibration signals according to a binary code and steps said second set of calibration signals according to a thermometer code once per full count iteration of said first set of calibration signals.