A stable algorithm for interfacing active and nonlinear devices with the ADI-FDTD method

This letter presents the algorithm to include active and nonlinear lumped devices in three-dimensional alternating-direction-implicit finite-difference time-domain simulations. The late-instability is considered and a late-stable algorithm is proposed. Numerical experiments validate the robustness of this algorithm. It can be applied to the analysis of radio frequency and microwave circuits.