| 摘要 |
PURPOSE:To set an output level in a wide range and to make the fluctuation due to temperature slight, by taking out a part of the output of an amplifier, whose gain is controlled, by a variable capacity or a variable resistance. CONSTITUTION:The output of an amplifier 3 is led to not only a terminal 9 but also a detector 6 through a variable capacity element 11. When the capacity 11 is reduced, the output of the amplifier is almost led to the terminal 9 and is set to a high level; and when the capacity 11 is increased, the output is set to a low level to increae the output to the detector 6 side. At this time, the matching condition for the output level of the terminal 9 is shifted from that for components absorbed to the detector 6 side from the output level of the amplifier 3, and the output level of the terminal 9 is reduced by components reflected to the amplifier, however, the attenuation quantity is small. Consequently, reduction of a maximum gain is small. Further, since the branching output is increased, the detection input level can be high, and an output level is st in a range wider than the operation level of the detector 6. When a variable resistance element 20 is used, the output level becomes slightly higher due to loss. |
