Simultaneous and Synchronous Measurement of Even and Odd Order Nonlinear Distortion Terms

摘要

Nonlinear distortion of different orders is usually measured at different frequencies, such as 2/ and 3/ for harmonic distortion and f + f% and 2/2 — /i for two-tone intermodulation distortion (IMD). This limits the physical insight available from these measurements because the distortion products are generated at different frequencies and different spatial locations in a distributed element device sample. This paper will describe a new technique to characterize nonlinear distortion in which products of even and odd order are generated at the same frequency and the same location in the driving field region. Two probing tones at frequencies /i and /2, which are very similar in frequency, are introduced at a specific location with a small probe. This determines the location of the nonlinear generation. A third driving tone at fs, which is much higher in frequency than /i and /2, determines the frequency of the nonlinear generation. With the three tones, 2nd order intermodulation occurs at fa + fi and 3rd order intermodulation occurs at fz + (/b — /i)i among other mixing terms. By setting fz much higher than /i and /2 by at least two orders of magnitude, the 2nd and 3rd order nonlinearities are generated at virtually the same frequency.