Patent ID: 6686789
Filing Date: 2004-02-03
Classification: G05F

Abstract:
A reference circuit comprising:a reference source including an output for generating at least one of a reference voltage and a reference current; an activity detector configured to measure an activity level of at least a portion of another circuit coupled to the reference circuit and to generate at least one control signal representative of the activity level; and a controller configured to dynamically change an output impedance of the reference circuit in response to the at least one control signal, whereby the output impedance of the reference circuit is reduced when activity is detected in the other circuit; wherein at least one of the reference voltage and the reference current is substantially unchanged between a period during which no activity is detected in the other circuit and a period during which activity is detected in the other circuit; wherein the controller comprises at least one switch operatively coupled to the output of the reference source, the at least one switch including at least one control input for receiving the at least one control signal, the at least one switch being configured to provide a substantially low resistance electrical connection between the output of the reference source and one of a positive voltage supply and a negative voltage supply; wherein the controller further includes at least one resistor operatively coupled to the at least one switch and in series between the output of the reference source and one of the positive voltage supply and the negative voltage supply, a resistance value of the at least one resistor being selected to provide a predetermined output impedance of the reference circuit when activity is detected in the other circuit.