| 摘要 |
PURPOSE:To reduce the switch noise without using a switch having a small amount of switch noise, by supplying the output of a buffer amplifier to a discriminating circuit only in a receiving period which is set for reception of a received burst signal. CONSTITUTION:A transmitted burst signal S is supplied to a receiving circuit 11; while a received burst signal R sent from a transmission line 8 is supplied to a receiving circuit 11 via a transformer 9. At the circuit 11 a buffer amplifier 13 amplifies and then delivers both signals S and R. A switch 12 conducts only in a receiving period of a high level of a control circuit 15 to delete the amplified signal S and supplies only the signal R to a discriminating circuit 14. In this case, the noise due to the switch 12 is supplied to the circuit 14. However, the noise is satisfactorily reduced compared with the level of the amplified signal R since the switch 12 is provided to an output stage of the amplifier 13. |
