Patent ID: 8902557

Claim:
A laser diode and protection circuit combination comprising: a laser diode having an anode terminal and a cathode terminal; a laser diode protection circuit including: an enhancement-mode N-channel MOSFET having a gate, a drain, a source and a body diode, the gate controlling a resistance to current flow from the drain to the source, the body diode allowing current flow from the source to the drain, the drain and source connected to the anode and cathode terminals, respectively; a capacitor connected between the anode terminal and the gate; and a first resistor connected between the gate and the cathode terminal; wherein the laser diode protection circuit is configured such that, with power turned off to the laser diode, the laser diode protection circuit provides protection during: a positive electrostatic discharge (ESD) event by conducting current through the MOSFET from the drain to the source; and a negative ESD event by conducting current through the body-diode of the MOSFET; and wherein when the positive ESD event occurs during normal operation of the laser diode, the laser diode shares a portion of the excess current from the positive ESD event with the MOSFET.