Advances in the simulation of nonlinear microwave circuits of autonomous nature are presented, covering three relevant aspects: potential instability of power amplifiers under output mismatch effects, design of dual-band frequency dividers, with interest in multi-band communication systems, and oscillator phase-noise analysis. The instability under mismatch effects is predicted through the calculation of a 3-port scattering matrix, at three relevant sideband frequencies, which is obtained by linearizing the circuit about the large-signal steady-state solution. The dual-band divider is based on a parallel configuration, using two types of inductor-varactor cells, as well as a simultaneous design/optimization of two identical circuits, each operating at one of the two frequency bands. Finally, a new phase-noise analysis method able to predict the near-carrier spectral density in the presence of near-critical poles is described.

Work funded by the Spanish Ministry of Economy and Competitiveness (TEC2014-60283-C3-1-R), ERDF/FEDER and the Parliament of Cantabria (12.JP02.64069).