| 摘要 |
A communication circuit capable of accurately detecting the signal level of the transmitted signal without impairing interchangeability with respect to an existing communication circuit. The communication circuit includes a first arithmetic unit 110 and a second arithmetic unit 120. The first arithmetic unit 110 executes arithmetic operations of K=R1/(R1+R2) V4=V3-KxV1 where V1 is a voltage of a transmission signal on a receiving side 100, R1 is a transmission impedance on the receiving side 100, V2 is a voltage of the transmission signal on a transmitting side 200, R2 is a transmission impedance on the transmitting side 200 and V3 is a voltage of the transmission signal transmitted to the receiving side 100 via a control line CL interconnecting the transmitting side 200 and the receiving side 100. The second arithmetic unit 120 executes an arithmetic operation of V5=2xV4 using the result of the operation by the first arithmetic unit 110 and detects the transmission level of the receiving side 200 with the voltage V5 resulting from the arithmetic operations being set so as to be the voltage V2 of the transmitted signal on the transmitting side 200.
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