| 摘要 |
PROBLEM TO BE SOLVED: To protect a high-frequency power amplifier circuit for mobile communications, etc., from damages, based on its load impedance variation, make a system designer free from the design of a protective circuit applicable thereto and realize applications to various systems, with a low cost and compact constitution. SOLUTION: A protection circuit has a circuit for detecting the collector voltage at the collector of a high-frequency power amplifier transistor during high frequency operation, and a circuit for dividing a current, depending on the collector voltage at the base of the transistor. The protective circuit is formed into one chip with the high-frequency power amplifier transistor. COPYRIGHT: (C)2004,JPO
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