FDTD modeling of arbitrary linear lumped networks and practical active devices

Two FDTD modeling approaches for lumped circuits are introduced in this paper. One is for arbitrary linear lumped networks based on piecewise linear recursive convolution (PLRC) technique, and it has the same accuracy as previous techniques, but has an advantage of less storage variables. The other is for active devices characterized by measured S-parameters by means of vector fitting (VF) technique, and it avoids the time-domain non-causality occurred in the previous techniques. To show the validity, two microstrip circuits are investigated.