An improved version of the almost periodic Fourier transform algorithm with applications in the large-signal domain

The waveform balance (WB) approach is combined with a modified form of the almost periodic Fourier transform (APFT) algorithm, resulting in an approach in which the number of randomly selected sampling points is increased, the overall computation accuracy is enhanced, the spread among results is reduced, and the computation time is practically unchanged. This approach is applied to the evaluation of large-signal S-parameters of a MESFET and to the calculation of its 1-dB compression power, the intermodulation distortion products, and the third-order intercept points (IP₃) for a range of frequencies. The results are in excellent agreement with those parameters that are available from the manufacturer´s measurements. The conversion gain of a MESFET mixer is calculated, and the reduced spread among the results is compared with that obtained by use of the original APFT algorithm