| 摘要 |
PURPOSE:To miniaturize an incoming field detecting circuit of a radio receiver by sharing a circuit which rectifies the input signals to be supplied to at least two circuits among those to be supplied to a squelch circuit, an incoming field intensity detecting circuit and a carrier detecting circuit respectively. CONSTITUTION:The out-of-band noise component contained in the signal supplied to an output terminal 1 for demodulation signal is extracted via a BPF and then supplied to a noise amplifier N.AMP to perform the desired amplification. Then the output of amplification is converted into a direct current by a rectifying circuit DET and allocated to a squelch level setting circuit SQ, an incoming field detection deciding circuit COMP and a carrier detection setting circuit CD respectively. The output of the SQ is connected a speaker switch SP.SW, etc., and the COMP is connected to an LED. While the output of the CD is supplied to a control part CONT. As a result, at least two circuits can be shared as a rectifying circuit instead of plural rectifying circuits.
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