| 摘要 |
An overvoltage protector consists of a 4-layer diode having a buried region located adjacent to the central junction of the diode and of greater impurity concentration than the layer of the same conductivity type adjacent to it, so that the current through the diode preferentially flows through the buried region. The buried region is of smaller area than the emitter junction, so that avalanche multiplication in the buried region determines the breakover current of the diode. The holding current of the diode is set by parts of the second layer which perforate the first layer (emitter) thereby forming a resistive path in parallel with the emitter junction. A device for protecting against voltages of different polarities is decribed comprising two such diodes formed in parallel and connected in opposite senses with a common third layer.
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