| 摘要 |
PURPOSE: A device for controlling the automatic gain of an amplifier is provided to make it easier to vary the tuning and stabilize the operation at a low voltage. CONSTITUTION: In a device of controlling the automatic gain of an amplifier, a divider divides the input power. An input power detector(26) detects the divided power. The first up-converter(22) converts up the main power produced by the divider. An attenuator(23) attenuates the output power from the first up-converter. The second up-converter(24) filters and amplifies the attenuated power. A directional coupler(25) couples the output power from the second up-converter(24). An output power detector(28) detects the output power from the directional coupler(25). A controller(27) controls the attenuator(23) after comparing the output power from the input power detector(26) with the output power from the output power detector(28).
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