| 摘要 |
PURPOSE:To obtain a booster device which can facilitate easy control of its gain by amplifying the oscillation signal of an oscillation circuit after mixing it into the booster input signal and extracting the signal component of the oscillation frequency at the output side to detect the distortion of the output signal of the booster in response to the level reduction of said signal component. CONSTITUTION:The output signal of an amplifier circuit 4 has distortions when the input/output characteristics of the circuit 4 exist in a nonlinear region although the voltage of a level detection terminal is kept constant. Then the oscillation signal of an oscillation circuit 2 is suppressed in the circuit 4 by a high frequency video signal supplied from an input terminal Ti. Thus the level of the oscillation signal is reduced and therefore the DC voltage is reduced at a level detection terminal Tc. In such way, the voltage of the terminal Tc is reduced compared with an input non-signal mode in case the output signal has distortions at an output terminal To for the high frequency video signal. Thus it is possible to detect the signal distortion of the terminal To by detecting the reduction of the voltage of the terminal Tc. In other words, it is possible to obtain the maximum level of the booster output signal with no distortion by controlling the gain of the circuit 4 and the like method.
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