Patent ID: 7477497

Claim:
An electrostatic discharge (ESD) bypass device for an emitter follower circuit, comprising: a bipolar transistor discharge device connected in parallel with the emitter follower circuit; and control circuitry associated with the discharge device, the control circuitry configured to prevent bypass current conduction through the discharge device in a normal mode of operation in which power is connected to the emitter follower circuit, and configured to cause the discharge device to conduct bypass current during an ESD event, the control circuitry further comprising: a first transistor configured to pass input current to the discharge device for activating the discharge device during the ESD event, and the first transistor further configured to prevent input current passing therethrough during the normal mode of operation, wherein the first transistor comprises a PFET having a gate terminal coupled to an RC network included within the control circuitry; and a second transistor configured to shunt leakage current, associated with the first transistor in the normal mode of operation, from the input of the discharge device, and the second transistor farther configured to prevent shunting of input current from the first transistor to the discharge device during the ESD event, wherein the second transistor comprises a grounded-gate PFET connected between the first transistor and an emitter terminal of the discharge device.