OFDM-BASED AUTOMATIC GAIN CONTROL CIRCUIT AND AUTOMATIC GAIN CONTROL METHOD

摘要

PROBLEM TO BE SOLVED: To efficiently control variable gain amplifiers within the dynamic range of an A/D converter in gain control of a signal modulated by an OFDM method.;SOLUTION: A gain control circuit 110 of an automatic gain control circuit increases the gain of an RF variable gain amplifier 102 if a comparison in a first comparator 111 finds that a signal level of an intermediate frequency signal amplified by an IF fixed gain amplifier 106 is equal to or lower than a first threshold, increases the gain of an IF variable gain amplifier 107 if a comparison in a second comparator 112 and a third comparator 113 finds that the signal level of the intermediate frequency signal amplified by the IF fixed gain amplifier 106 has a frequency of exceeding a second threshold equal to or lower than a predetermined value and is equal to or lower than a third threshold, and decreases the gain of the IF variable gain amplifier 107 if a comparison in the third comparator 113 finds that the signal level of the intermediate frequency signal amplified by the IF fixed gain amplifier 106 is higher than the third threshold.;COPYRIGHT: (C)2013,JPO&INPIT