Patent ID: 8368458

Claim:
An impedance tuning apparatus, comprising: an operation amplifier, having a first input terminal, a second input terminal, and an output terminal, wherein the first input terminal receives a basic voltage, and the second input terminal is coupled to a first endpoint; a reference resistor, wherein a terminal of the reference resistor is coupled to a reference voltage; a tuned resistor, wherein a terminal of the tuned resistor is coupled to the reference voltage; a switching module, for receiving a control signal, and coupling the first endpoint to the other terminal of the tuned resistor or the reference resistor according to the control signal for generating a tuned current or a reference current respectively; a current generator, coupled to the switching module, for receiving and mirroring the reference current or the tuned current to generate a first current or a second current respectively; a current detector, for receiving the first current and the second current, and outputting current values of the first and the second currents; and a controller, coupled to the current detector and the tuned resistor, for receiving the current values of the first and the second currents, and tuning a resistance value of the tuned resistor according to the current values of the first and the second currents.