Analysis and optimization of solid-state microwave circuits for digital communications

This thesis proposes new methods for the simulation and optimization of nonlinear microwave circuits in modulated signal environments.; First, a new Harmonic Balance method is introduced that overcomes the difficulties seen by the classical techniques in applications to modulated signals. The proposed method is an efficient and a most general one, in that the excitation bandwidth is arbitrary and that it is applicable to large signal operation. The method relies on an application of the newly proposed Modified Fixed-Point iteration, which achieves a reduction in problem complexity by decoupling the Harmonic Balance equation into a sequence of much smaller, sparse linear systems.; Next, “envelope domain” methods are proposed for the simulation of mixers and weakly nonlinear amplifiers subject to narrowband-modulated excitations. In both cases, processing speed is state-of-the-art and is achieved by a novel extension of the classical Nonlinear Currents approach.; Finally, the thesis proposes methods for nonlinear circuit optimization in modulated signal environments. Here, the power of gradient optimizers is combined with a new approach for gradient extraction, yielding a highly efficient and automated design methodology.