| 摘要 |
An OFDM(Orthogonal Frequency Division Multiplexing) receiver and an automatic gain control circuit thereof are provided to suppress the degradation, without clipping a signal to the input of an A/D(Analog/Digital) conversion circuit, in a moving channel. According to an OFDM(Orthogonal Frequency Division Multiplexing) receiver receiving and demodulating an OFDM signal, a variable gain amplifier unit controls the signal level of an intermediate frequency signal. An automatic gain control circuit controls the gain of the variable gain amplifier unit. The automatic gain control circuit comprises a clip detection unit(131) comparing the detection number of temporal clips where the signal level of the intermediate frequency signal exceeds the parameter clip level and then detecting the period exceeding the clip number threshold value. An accumulation unit(132) accumulates the detection output of the clip detection unit. A target value determining unit(133) is supplied with the accumulation output of the accumulation unit The target value determining unit comprises a first comparison unit and a second comparison unit, and determines the target value of automatic gain control adaptively by decreasing or increasing the target value on the ground of the comparison output of the first and the second comparison unit.
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