Patent ID: 7902860

Claim:
A semiconductor circuit, comprising: a first circuit having nonlinear resistance characteristics; and a second circuit for impedance adjustment use having nonlinear resistance characteristics which are the same as nonlinear resistance characteristics of the first circuit, wherein the second circuit includes: an operating point calculation circuit that includes a first CMOS circuit, a second CMOS circuit, a reference resistance and a first differential amplifier, and that is automatically configured to calculate, through feedback control, an operating point with the reference resistance and the second CMOS circuit, wherein the second CMOS circuit and the reference resistance are directly connected to one another during said calculation of said operating point and wherein the first differential amplifier compares an output from the first CMOS circuit and an output from the second CMOS circuit connected to the reference resistance and feedbacks a result of said comparing to the first CMOS circuit; and an impedance calculation circuit that calculates an impedance at the operating point calculated by the operating point calculation circuit.