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

Nonlinear distortion of di®erent orders is usually measured at di®erent frequencies, such as 2f and 3f for harmonic distortion and f1 +f2 and 2f2 - f1 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 f1 and f2, 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 f3, which is much higher in frequency than f1 and f2, determines the frequency of the nonlinear generation. With the three tones, 2nd order intermodulation occurs at f3+f2 and 3rd order intermodulation occurs at f3+(f2 - f1), among other mixing terms. By setting f3 much higher than f1 and f2 by at least two orders of magnitude, the 2nd and 3rd order nonlinearities are generated at virtually the same frequency.