| 摘要 |
PURPOSE: An AGC(Automatic Gain Control) circuit is provided to regularly adjust an IF(Intermediate Frequency) signal gain, by implementing memory based gain control circuit, used in a base station of a mobile communications system having a CDMA(Cord Division Multiple Access), in the IF board inside of the base station of a WILL(wireless local loop) system, by using an analog element, such as a pin attenuating circuit. CONSTITUTION: An AGC(Automatic Gain Control) circuit filters a required band frequency of an IF(Intermediate Frequency) signal, outputted from a RF(Radio Frequency) section inside of a base station of a WILL(wireless local loop) system, amplifying a regular level, and attenuates the IF signal gain according to control voltage and standard voltage, inputted so that the gain of the IF signal can maintain a standard value through the pin attenuating circuit. The AGC circuit outputs an OP AMP, amplified in a regular level, to a channel card of the base station after removing a noise of an I, Q signal, amplifying the IF signal, coupled by a coupler in a regular level, detects a peak of the IF signal,and outputs the detected peak to the pin attenuating circuit as control voltage, by amplifying the detected peak in a regular level.
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