| 摘要 |
PURPOSE:To provide the amplifier which can realize the APC(auto power control) function for the burst wave as well as the consecutive wave. CONSTITUTION:The input signal is attenuated by a variable attenuator 21, then it is amplified by an amplifier 22 to be outputted. The output signal is envelope-detected by a detector 33a. The detection signal is supplied to a sample-hold circuit 35. The input signal is envelope-detected by an input side detector 33b. The detection signal is compared with a prescribed reference signal in a comparator 36. With the comparison, the presence or absence of the input signal is detected. When no input signal is judged, a sample-hold circuit 35 is held. A smoothing circuit 34 supplies the held signal to the variable attenuator 21. Thus, when there is no input signal, the amplification factor is never varied. Thus, the APC circuit where the amplification factor is not varied even when the duty ratio of the burst wave is varied can be obtained. |
