Non-invasive waveform probing for nonlinear network analysis

A noninvasive technique has been developed for the measurement of fundamental and harmonic S-parameters as functions of input frequency and power. This technique was demonstrated on a GaAs FET by plotting its drain current versus voltage trajectory at 5 GHz. By superimposing the RF trajectory on the DC characteristics, the origin of the device nonlinearity was clearly shown. The results make it possible to characterize the nonlinear behavior and to verify the large-signal model of the device in both the time and the frequency domains.<
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