Fast Simulation of Microwave Circuits With Nonlinear Terminations Using High-Order Stable Methods

This paper describes a new method for transient simulation, using high-order stable methods, of microwave structures modeled using a large number of lumped components. The target of the proposed technique is circuit-based simulation of the large linear circuits that arise from full-wave modeling of distributed structures, such as transmission lines and microstrip elements, along with the terminating nonlinear devices. In this case, the cost of the solution of the linear system typically dominates the computational effort. The proposed method takes advantage of the special structure of the block matrices in these applications to reduce the computational cost significantly. The core of the proposed algorithm is based on the idea of “node tearing” to separate the large linear sub-circuits from the nonlinear devices. This idea faciliates handling the linear sub-circuits using a better matrix factorization technique, resulting in faster simulations compared to classical techniques.