Patent ID: 6825718
Filing Date: 2004-11-30
Classification: H03F,H03H

Abstract:
An impedance matching circuit, comprising:a resistor unit for receiving an input signal; an OP amplifier circuit having an output terminal and an input terminal which is connected with said resistor unit; a feedback selecting circuit which is controllable by a first control voltage, said feedback selecting circuit being connected in parallel with the OP amplifier circuit and also being connected with the resistor unit; and a resistor selecting circuit further having an input end connected to said output terminal and an output end for outputting an output signal, said resistor selecting circuit being connected with and controlled by the feedback selecting circuit so as to adjust an impedance of the resistor selecting circuit according to said first control voltage; wherein the resistor unit and the feedback selecting circuit are designed in such a manner that the resistor unit is able to compensate an equivalent resistance of the feedback selecting circuit when said first control voltage is applied thereto.