| 摘要 |
PROBLEM TO BE SOLVED: To provide a receiving circuit capable of securing noise resistance even at a failure in the circuit and preventing a malfunction by the failure in the circuit. SOLUTION: A current detecting part 19 is connected alternately in series/ parallel with a pair of first and second noise by-passes 12, 14 having predetermined impedance by switching first and second switches 17, 18 which are turned complimentarily on/off to confirm normality of each of the noise by-passes by conduction to the current detecting part 19 when each of the noise by-passes is connected in series and to restrain effect of noise in the noise by-pass connected in parallel therewith. Current detection output from the current detecting part 19 is input in a deciding circuit 20 and the deciding circuit 20 notifies presence/absence of a received signal on the basis of an output state of the current detection output.
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