| 摘要 |
PROBLEM TO BE SOLVED: To provide a power amplifier with a bias changeover switch employing a GaAs FET used at a microwave band. SOLUTION: In the power amplifier shown in Figure, the FET 2 amplifies a microwave band high frequency signal received from an input connection line 1, and the amplified signal is outputted from an output connection line 3 through a directional coupler 5. The high frequency signal extracted by the directional coupler 5 is converted into a DC voltage in proportion to an output signal level by a detector 6. Thereafter, when the output level reaches a prescribed level or over (when the output level exceeds a preset value) a contactless switch 10 controls a drain current. In an idling state and when the output level is low, a gate power supply A8 is used and when the output level is high, a gate power supply B9 is used. COPYRIGHT: (C)2005,JPO&NCIPI
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