GMRES preconditioners for multivariate steady-state time-domain method (RF simulation)

Envelope methods play an important part in current RF simulation. We focus on an envelope method called the multivariate steady-state method (MSSTD). The method solves the steady state of a circuit especially in the case when signals at two very different frequencies are present, and harmonic balance is inefficient due to the shape of the signals. Different preconditioners for the iterative matrix solving method (GMRES) have been tested. Simulation results show that the preconditioner consisting of larger diagonal blocks decreases the number of iteration cycles needed and also the simulation time. However, other types of preconditioners should be studied to find a more robust and reliable solver for this type of problem and therefore one new approach has been proposed.