METHOD AND APPARATUS FOR ESD PROTECTION

摘要

Some disclosed embodiments of an electrostatic discharge protection circuit include a shunt device coupled between a power supply terminal and ground to shunt current from the power supply terminal to ground in response to a trigger signal received at an input of the shunt device and a latch coupled to the shunt device input to latch the trigger signal received at a latch input. Some embodiments also include a buffer coupled to the latch input to receive the trigger signal at a buffer input and a comparator coupled between the power supply terminal, ground, and the buffer input to respond to an electrostatic discharge event and produce the trigger signal at a comparator output. In some embodiments the comparator further includes a first current mirror comprising a first sense device coupled to the power supply terminal and a first mirror device coupled between a comparator output and the power supply terminal and a plurality of bias devices coupled to the first sense device, at least two of the plurality of bias devices coupled in series at a bias output line. In some embodiments the comparator further includes a transconductance device comprising an input coupled to the power supply terminal and a control input coupled to the bias output line and a second current mirror comprising a second sense device coupled between the transconductance device and ground and a second mirror device coupled between the comparator output and ground, the second mirror device coupled in series with the first mirror device. In some embodiments the comparator also includes a compensating device coupled between the plurality of bias devices and ground.