HIGH-FREQUENCY POWER SUPPLY

PROBLEM TO BE SOLVED: To provide a high-frequency power supply capable of detecting occurrence of abnormality in a detection system and precisely protecting a high-frequency power amplification section and its load. SOLUTION: Two detection systems for detecting a basic frequency component of progressive wave power from an output of a directional coupler DC inserted between the high-frequency power amplification section AMP and the load LD are arranged, and it is determined that either of the detection systems is abnormal when output levels of both detection systems are different. The detection system for detecting harmonic components of reflected wave power from a detection signal at a progressive wave side of the directional coupler DC via a high-pass filter, and the detection system for detection harmonic components of the reflected wave power from a detection signal at a reflected wave side of the directional coupler DC are provided, and when output levels of both detection systems are different, it is determined that either of the detection systems is abnormal. When it is determined that either of the detection systems is abnormal, protection control for restraining or stopping an output of the high frequency power amplification section is carried out. COPYRIGHT: (C)2009,JPO&INPIT