Patent ID: 8467162

Claim:
An electrostatic discharge (ESD) protection circuit electrically connected between a first power rail and a second power rail, the ESD protection circuit comprising: an ESD protection device, comprising: a first BJT of a first conductive type, having a first base, a first emitter and a first collector, the first emitter being electrically connected to the first power rail; and a second BJT of a second conductive type, having a second base, a second emitter and a second collector, the second emitter being electrically connected to the second power rail, the second collector being electrically connected to the first base, and the second base being electrically connected to the first collector; a voltage drop element, electrically connected between the first base and the first power rail, and the voltage drop element providing a voltage drop between the first base and the first emitter to turn on the ESD protection device faster during an ESD event, wherein the voltage drop element comprises series connected parts including a number of forward biased diodes and a resistor a first switching device, electrically connected between the first base and the first power rail; and a first low-pass filter, electrically connected between the first power rail and the first switching device; wherein when an ESD event does not occur, the first switching device is turned on, and a potential of the first base is larger than or equal to a potential of the first emitter; and when the ESD event occurs, the first switching device is turned off, and the potential of the first base is smaller than the potential of the first emitter.