Patent ID: 6963112
Filing Date: 2005-11-08
Classification: H01L

Abstract:
1. An electrostatic discharge (ESD) protection circuit for preventing a pad-to-pad ESD charge, the protection circuit for each pad of an integrated circuit comprising: a current dissipation module with an N-type MOSFET connected in parallel with a bipolar junction transistor (BJT) wherein the drain of the MOSFET and the collector of the BJT are connected to a first common node and the source of the MOSFET and the emitter of the BJT are connected to a second common node connectable to a second operating voltage; a diode string connected to a first pad at its anode end having a total forward voltage drop more than a first operating voltage and with its cathode end connected to the body of the MOSFET, the base of the BJT, and to the second common node through a resistor; a first diode with its anode end connected to the first pad and its cathode end connected to the first common node; and a second diode with its anode end connected to the second common node and its cathode node connected to the first pad, wherein when the ESD charge causes a voltage on the first pad to surpass the total forward voltage drop of the diode string, the ESD charge injects a direct current to the base of the BJT so as to enhance the dissipation of the ESD charge and wherein the diode string keeps the voltage on the first pad between the first and second operating voltages.