POWER AMPLIFIER DEVICE

PURPOSE:To prevent a metal semiconductor type field effect transistor FET from chattering by cutting off the drain bias voltage of a power amplifier when the temperature of a housing rises above reference temperature, and providing a comparing means with hysteresis characteristics. CONSTITUTION:When the housing temperature rises above the reference temperature, the output of the comparing means 33 rises to H, for example, and the drain bias voltage and the FET 24 are cut off. The comparing means 33 has the hysteresis characteristics, so the output of the comparing means 33 falls to L, for example, after the housing temperature drops by temperature corresponding to the hysteresis width and the drain bias voltage and FET 24 conduct. Consequently, the FET is prevented from chattering and the power amplifier can operate until the FET is cut off again.