ANALYSIS OF HIGH-POWER AMPLIFIER INSTABILITY DUE TO F(0) 2 LOOP OSCILLATION/

A novel nonlinear analysis method of high power amplifier instability has been developed. This analysis method deals with a loop oscillation in a closed loop circuit and presents the conditions for oscillation under large-signal operation by taking account of a mixing effect of F ETs. Applying this analysis to the high power amplifier instability th at an output power for the fundamental wave (f(0)-wave) decreases at s ome compression point where a half of the fundamental wave (f(0)/2-wav e) is observed, it has been found that this instability is caused by a n f(0)/2 loop oscillation. In addition, it has been verified by analys is and experiment that the oscillation can be removed by employing an isolation resistor in a closed loop circuit.