| 摘要 |
PROBLEM TO BE SOLVED: To provide an OFDM receiver wherein a signal is not clipped at an input of an A/D conversion circuit so as to suppress deterioration. SOLUTION: An automatic gain controller includes: a clip detector comparing a clip number threshold value with a detected number of transient clips in which a signal level of the intermediate frequency signal resulting from applying frequency conversion to a received signal exceeds a parameter clip level, so as to detect a period where the detected number exceeds the clip number threshold value; an accumulator accumulating a detection output of the clip detector; and a target value decision circuit to which an accumulation output of the accumulator is supplied. The target value decision circuit includes: a first comparator for comparing the accumulation output of the accumulator with a clip threshold value to discriminate occurrence of a clip; and a second comparator for comparing the accumulation output of the accumulator with a non-clip threshold value to discriminate non-occurrence of a clip. The target value decision circuit decreases a target value by a prescribed value on the basis of a comparison output of the first comparator and increases the target value by a prescribed value on the basis of a comparison output of the second comparator thereby adaptively determining the target value TG for automatic gain control. COPYRIGHT: (C)2008,JPO&INPIT
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