发明公开
EP0740859A4 ELECTROSTATIC DISCHARGE CIRCUIT FOR HIGH SPEED, HIGH VOLTAGE CIRCUITRY 失效
电气放电电路基础上,高速高压电路

ELECTROSTATIC DISCHARGE CIRCUIT FOR HIGH SPEED, HIGH VOLTAGE CIRCUITRY
摘要:
A protection circuit includes a first controlled path for discharging negative ESD pulses introduced at a signal node (30). The first controlled path is from the signal node to (Vcc) via the source and drain electrodes of a first transistor (36). The gate of the transistor is at a soft ground by connection of the gate through a resistor (42) and an inverter (44) to a fixed voltage supply potential (Vcc). A second controlled path discharges positive ESD pulses via source and drain regions of serially connected second (50) and third (52) transistors to ground. The second transistor (50) has a gate tied at (Vcc) by means of a resistor (62) and an inverter (66) to ground. The third transistor (52) is at soft ground by means of a resistor (64) and inverter (68) to (Vcc). The third transistor is turned on by a positive voltage exceeding the threshold voltage of the third transistor, but the second transistor prevents damage to the third transistor by limiting the voltage applied to the third transistor. The protection circuit may include a third controlled path through a fourth transistor (54), if low voltage circuitry (32) is tied to the signal node (30). The fourth transistor (54) includes a gate that is tied high by connection of the gate to ground via a resistor (82) and inverter (84).
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