ABSTRACT
This chapter presents the characterization and measurement of nonlinearities in microwave circuits. It focuses on standard techniques for analog and digital communication circuits. Fortunately, extraction of high order Volterra series representations of nonlinear microwave circuits is rarely required to gain useful information on the deleterious and/or useful effects of distortion on common signals. Thus direct measurement of multitone intermodulation distortion (IMD) is often necessary to insure adequate carrier-to-interference level within a communication system. The IMD performance of microwave circuits is important because it can create unwanted interference in adjacent channels. While powerful methods have been developed to analyze complex linear circuits, it is unfortunate that almost all physical systems exhibit some form of nonlinear behavior. A fundamental result of the distortion of nonlinear circuits is that they generate frequency components in the output signal that are not present in the input signal.
