| 摘要 |
PROBLEM TO BE SOLVED: To rightly detect a carrier even when a capacitor C12 for integration for outputting a level Det is made into capacitor, which can be integrated, in a carrier detecting circuit 30, which is used for the receiver of an infrared remote controller or the like, for preparing the carrier detection level Det on the basis of a received signal and detecting the presence/absence of carrier while using that level Det. SOLUTION: The capacitor C12 is not charged/discharged corresponding to whether or not each of pulses in a carrier frequency to be detected exceeds the level Det but the pulse in the carrier frequency is detected for each group by a detector 33 and time detecting that group is integrated by an integrator 34 so that the level Det can be prepared. Therefore, it is enough for a transistor for charging/discharging the capacitor C12 in the integrator 34 to have not the carrier frequency but responsiveness to the frequency of a baseband component and while securing a margin to the response of the transistor, a charging/ discharging current to the capacitor C12 can be made a little.
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