This paper discusses the large-scale circuit simulation and incremental circuit simulation, both which are based on Selective-tracing Waveform Relaxation (STWR) algorithm. Utilizing the concept of exactness in simulating subcircuits, STWR usually spends fewer subcircuit calculations than traditional algorithms, such as WR and ITA. But STWR suffers from robustness problems. Techniques are proposed to reinforce characteristics of STWR. This paper also describes the incremental circuit simulation that is based on STWR. This new method manages the influence of design changes more exactly than previous works, and hence exhibits better efficiency. We have implemented all proposed methods and performed experiments. Simulation results justify better characteristics of proposed methods.
