Time-Efficient Adaptive Procedure for Identification of Multitone X-Parameters

A novel measurement procedure for the time-efficient identification of multitone X -parameters of active microwave devices and circuits is introduced. Over a given bandwidth, the procedure allows for an adaptive selection of key spectral components necessary for determining the X -parameters characteristics with a minimum measurement effort. The sequential selection is based on the divide-and-conquer algorithm. It results in a huge reduction of the measurement time in comparison to the situation when model coefficients at all spectral components are identified. To validate the procedure, an off-the-shelf broadband power amplifier (PA) was characterized under wideband large-signal excitation conditions. Moreover, small-signal terms at all relevant frequencies were collected as a reference and compared with the results provided by a time-efficient adaptive procedure (TEAP). The proposed method resulted in twenty times reduction in the number of samples required to characterize the PA. As an application example, the small-signal coefficients identified with the TEAP are used to correct characterization results for the measurement instrument's output mismatch. The mismatch-corrected output signal of the PA under test was represented accurately with the error-vector-magnitude of only 0.132%.