A bidirectional trigger diode (DIAC) is a semiconductor device that is a bidirectional switching device at both ends that achieves higher trigger stability and noise immunity. DIAC works by applying a positive or negative supply voltage across the bidirectional trigger diode but not reaching the trigger voltage, with only a small leakage current flowing through the device. When the applied voltage increases to a value equal to the breakdown voltage, an avalanche breakdown occurs at the reverse bias junction. That is, the current increases with the increase in the value of the applied voltage. During the turn-on period, the voltage at both ends drops to a very small amount, which is equal to the conduction state of the bidirectional trigger diode, and it can do fast switching work at a certain frequency