| 摘要 |
PROBLEM TO BE SOLVED: To provide a 2/4-wire conversion circuit where a second harmonic of a carrier signal with a lower frequency generated from a photocoupler is prevented from being a disturbing wave of a carrier signal with a higher frequency. SOLUTION: A 2nd harmonic H24' of a carrier signal S12 generated by a nonlinear amplifier circuit 15 cancels a secondary harmonic H24 of a carrier signal S12 generated from a photocoupler PC4 in a differential amplifier circuit 13 to prevent the secondary harmonic H24 from being outputted from a reception terminal R of a 4-wire line. Thus, the secondary harmonic wave of a carrier signal with a low frequency generated from the photocoupler is prevented from being a disturbing wave of a carrier signal with a higher frequency in the 2/4-wire conversion circuit in spite of a simple configuration. Furthermore, the 2/4-wire conversion circuit is made small and the cost is reduced.
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