FDTD analysis of active circuits based on the S-parameters [microwave hybrid ICs]

This paper describes a S-parameter-based formulation of the extended finite-difference time-domain algorithm for the purpose of modeling microwave devices. In the active region the Maxwell equations are coupled with an active device model which simulates the equivalent current source. The S-parameters of active devices are treated by extrapolation method and even conjugate continuation, and then expressed in time domain by Fourier transform to obtain the relations between the equivalent current source and electric field. The simulation results are compared with the data obtained by Touchstone and show good agreement.