Radio frequency and microwave numerical simulation techniques based on multivariate formulations

Simulating modern wireless communication systems is today a hot topic. Serious difficulties arise when these systems are highly nonlinear heterogeneous circuits, combining radio frequency (RF) and baseband analog circuitry and digital components, operating in widely distinct time scales. This paper briefly reviews some recently proposed innovative techniques based on multivariate (multidimensional) formulations, which were especially conceived to efficiently simulate modern wireless systems, as a whole, at the circuit level. In order to evidence the achievements brought by the multivariate strategies into the field of RF and microwave circuit simulation, as well as their most relevant limitations, several powerful numerical techniques, operating in time, frequency, or hybrid (combination) domains, will be addressed.