| 摘要 |
PURPOSE:To realize a protection circuit in which transmission is inhibited when an antenna is not connected to prevent a power amplifier from being driven in a no load state. CONSTITUTION:A DC voltage is applied to an antenna 7 having a low DC resistance between a radiation conductor and a ground terminal. When the antenna 7 is not connected, an H level control signal 10 is fed to a switch circuit 2, and in this case, since the switch circuit 2 is opened, no bias power supply is fed to a power amplifier 1 and the transmission is inhibited. Thus, when the antenna 7 is not connected, the transmission is inhibited thereby preventing the power amplifier from being driven in a no load state. |
