| 摘要 |
PROBLEM TO BE SOLVED: To provide a signal isolation circuit in which a circuit scale can be made small by eliminating an increase in the circuit scale because a signal isolation circuit for isolating a signal in which a signal of HART communication is superimposed on a DC current signal needs a circuit for isolating a HART signal separately from an isolation circuit for isolating the DC current signal.SOLUTION: In the signal isolation circuit, a chopper 41 converts the DC isolation signal into an alternating current higher than the maximum frequency of a superimposed HART signal, a transformer 42 isolates the alternating current, and a rectifying and smoothing part 43 having a smooth characteristic higher than the maximum frequency of the HART signal rectifies and smoothes an alternating current induced at the secondary side of the transformer 42, and the HART signal applied to an output side is outputted through an outputting part 44 which makes the HART signal pass through to an input side. The necessity of an isolation circuit of a HART signal is eliminated. |
