ESD protection devices for a differential pair of transistors

摘要

The invention provides a way of protecting a differential pair of transistors by providing a current path between input terminals of the transistors, while limiting the voltage across reversed biased junctions of the transistors. The invention also allows a larger swing of input voltage at the input terminals of the transistors. According to the present invention, an electrostatic discharge protection circuit is provided for protecting a differential pair of transistors. Each transistor includes first and second terminals and an input terminal. The second terminals of the transistors are connected to each other. The circuit comprises a pair of bypassing circuits and a clamping circuit. Each bypassing circuit is connected in parallel with a junction formed by the input and second terminals of an associated one of the transistors to limit a voltage across the junction when the junction is reverse biased. The clamping circuit is connected in parallel with the two input terminals of the transistors for setting an allowed differential voltage swing between the input terminals to a predetermined level.