Efficient algorithms for spectra calculations in nonlinear microwave circuits simulators

Two original and efficient discrete Fourier transform (DFT) algorithms for quasi-periodic signals are presented. These constitute important tools for computer-aided analysis, and design of microwave circuits driven by multiple input frequencies (e.g. mixers, (de)modulators, multitone amplifiers, etc.), which is still an open field. The efficiency of the algorithms is shown through a typical example, and a comparison with previously published methods is given. The proposed algorithms appear to yield no major difficulty; they can also be implemented quickly