| 摘要 |
The circuit prevents damage caused to a terminal when a send key is pressed in the absent of antenna, by using a cheap device. The circuit includes a PNP transistor (13) connected to a power amplifier (2) and a power supply, a first NPN transistor (14) controlled by a control signal generated by a CPU, a second NPN transistor (15) connected to an emitter of the first NPN transistor (14), a switch (12) having A port connected to a base of the second NPN transistor, B port connected to a power, and C port connected to the ground.
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