Nonlinear analysis of f/sub 0//2 loop oscillation of high power amplifiers

Abstract

A novel nonlinear analysis of high power amplifier instability has been developed. This analysis method deals with a loop oscillation and presents the conditions for oscillation under large-signal operation by taking account of a mixing effect of FETs. Applying this analysis method to the high power amplifier instability that an output power decreases at some compression point where an f/sub 0//2-wave is observed, it has been found that this instability is caused by an f/sub 0//2 loop oscillation. In addition, it has been verified by analysis and measurement that the oscillation can be removed by employing an isolation resistor in a closed loop circuit.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>