| 摘要 |
PURPOSE:To prevent the sidetalk in a steady way when the signal source impedance changes for the 2-line and 2-way communication circuit by providing the opposite- phase switching circuit and the forward feedback circuit. CONSTITUTION:The signal sent from signal source 21 is transmitted to signal source 22 via LPF30 containing switching circuit 26 and forward feedback circuit 31; while the signal from signal source 22 is transmitted to terminal 33 via circuit 31 and switching circuit 32. At the same time, the output of source 21 is supplied to phase inversion circuit 27 and switching circuit 28, and switching signals 34 and 35 featuring the opposite phase to each other are supplied to circuit 26, 28 and 32 from oscillator 29. The output level of circuit 28 is reduced properly to transmit the signal of source 21 to source 22 and not to terminal 33 owing to passing through circuit 32. Thus, the sidetalk to be given to terminal 33 can be prevented when the signal is transmitted from source 21 to 22. |
