Cross modulation and intermodulation in amplifiers at high frequencies

Cross modulation and intermodulation in amplifiers at high frequencies are investigated using the Volterra series approach. The general relationships between these forms of distortion are defined and the importance of phase in the specification of cross modulation is discussed. The use of feedback for distortion at high frequencies is investigated and it is shown that appropriate control of the feedback loop phase shift can result in substantial reductions in cross modulation over broad bandwidths. All theoretical conclusions are verified by circuit measurements at frequencies up to 200 MHz.