Patent ID: 7949975

Claim:
A method of extracting an equivalent circuit of a T-type transmission circuit, the T-type transmission circuit having a ground terminal for an AC signal and first and second terminals for signal transmission, the equivalent circuit having a T-type circuit and a π-type circuit, the T-type circuit having: a first lead line constant part, one end of which is connected to the first terminal and which has a first lead line resistor and a first lead line inductor connected in series; a second lead line constant part, one end of which is connected to the second terminal, the other end of which is connected to the other end of the first lead line contact part and which has a second lead line resistor and a second lead line inductor connected in series; a third lead line constant part, one end of which is connected to the ground terminal, the other end of which is connected to the other end of the first lead line constant part and the other end of the second lead line constant part, and which has a third lead line resistor and a third lead line inductor connected in series, the π-type circuit having: a first impedance circuit generated by a first coupling capacitor and an eddy current loss which are connected in series between the first terminal and the ground terminal; a second impedance circuit generated by a second coupling capacitance and an eddy current loss which are connected in series between the second terminal and the ground terminal; and a third coupling capacitor connected between the first and second terminals, the method comprising using one or more processors to perform the following: measuring signals of the first and second terminals to obtain S parameters; converting the S parameters into Z parameters to generate the T-type circuit by using the Z parameters; obtaining the first to third lead line resistors and the first to third lead line inductors in the T-type circuit based on the Z parameters corresponding to constants of the T-type circuit; subtracting the Z parameters corresponding to the T-type circuit from the Z parameters corresponding to all of the equivalent circuit to calculate the Z parameters of the π-type circuit; converting the Z parameters of the p-type circuit into the Y parameters; and calculating the first to third coupling capacitances based on the Y parameters.