| 摘要 |
PURPOSE:To provide a high frequency band and high output amplifier applicable to a system requiring a small channel spacing in which a problem of inter-adjacent channel interference due to distortion exists, and of small size and light weight without generating the distortion, and capable of issuing high efficiency/low distortion output. CONSTITUTION:The control circuit 34 of the high frequency band high output amplifier performs positive feedback control of an input application voltage to the gate of a final stage amplifier element 11 via an input side voltage supply part 23 setting a signal in which an input offset voltage Vgs offset is added on an input detection signal envelope-detected at an adder 32 as the input application voltage. When input with large amplitude is inputted, it arrives as the input of the final stage amplifier element 11 via a DC amplifier 20 and the adder 32, and a voltage feedback circuit 19 is operated setting operating points as classes B, C, then, the making of high efficiency/low distortion can be attained. When input with middle or small amplitude is inputted, the input of the final stage amplifier element 11 becomes shallow since the output of an input side detecting part 13 is decreased, and the operating point is moved to class A, and wave distortion can be improved by performing amplification in a linear operating area. |
