A Krylov-subspace technique for the simulation of integrated RF/microwave subsystems driven by digitally modulated carriers

This article introduces a new approach to the analysis of nonlinear RF/microwave systems or subsystems described at the circuit level and excited by sinusoidal carriers modulated by arbitrary baseband signals. The circuit is simulated by a sequence of harmonic-balance analyses based on a Krylov-subspace method driven by an inexact Newton loop, and suitably modified to account for coupling with a finite number of preceding time instants. The Jacobian matrix of the nonlinear solving system is computed by an exact algorithm, and its structure is shown to be very well suited for the application of Krylov-subspace techniques such as the GMRES method. In this way, problems with many millions of nodal unknowns may be efficiently tackled at the workstation level.