Power failure protection circuit based on single-pole three-throw switch

Under some abnormal conditions, power failure may occur in power supply of a high-power switch, and due to strong coupling between antenna units, the power-down switch receives a high-power signal coupled back by an adjacent antenna unit, resulting in over-temperature burnout of a PIN tube core connected in parallel in the switch. The invention provides a power-down protection circuit based on a single-pole three-throw switch, and the protection circuit can provide a protection function of bias voltage and current for a parallel PIN diode in an abnormal power-down state of the switch (+ 5V voltage loss). And the fault phenomena of burning and the like of the parallel PIN diode under a high-power radio frequency signal due to the lack of bias voltage and current can be avoided. 在某些异常情况下，高功率开关供电可能会出现掉电情况，由于天线单元之间的强耦合，掉电的开关会接收到相邻天线单元耦合回来的大功率信号，造成开关内部并联PIN管芯过温烧毁。本发明提出了一种基于单刀三掷开关的掉电保护电路，该保护电路在开关异常掉电状态下(+5V电压缺失)能够为并联PIN二极管提供偏置电压和电流的保护功能，避免并联PIN二极管因偏置电压和电流的缺失在大功率射频信号下出现烧毁等故障现象。