Efficient Procedures for Analyzing Large-Scale RF Circuits

The majority of CAD tools have limited modes of the sensitivity analysis: PSPICE only contains a static mode and SPECTRE includes frequency domain and static modes. However, many RF systems use symmetrical structures for enhancing the properties of the circuits. For such systems, the static sensitivities are zero in principle and therefore the time domain sensitivity analysis must be used. In the paper, a new recurrent formula for the time domain sensitivity analysis is derived, which uses by-products of an implicit integration algorithm. Moreover, for a very fast estimation of mixed products, an efficient procedure is described, which is also not implemented in PSPICE. Both methods are demonstrated by analyses of a four-quadrant RF multiplier.