| 摘要 |
PROBLEM TO BE SOLVED: To freely set an AM middle AGC sensitivity from the outside of an IC without increasing number of IC terminals and its chip size. SOLUTION: The operation sensitivity of an AM middle AGC depends on resistance division by resistors R3, R4, and when a switch element SW2 is made 'on' in the AM mode, the sensitivity is specified by a DC voltage applied from an input terminal 13. That is, a signal input line to an FM wide AGC detection section 9 and a DC voltage input line to specify the detection sensitivity of the AM middle AGC detection section 19 are used for a common input terminal.
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