Patents by Inventor Kwan Ting Ng

Kwan Ting Ng has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 9054485
    Abstract: A laser driver circuit compensates for non-linear behavior of Vertical-Cavity Surface-Emitting Laser (VCSEL) devices. A VCSEL has an internal parasitic capacitance that is charged while the VCSEL is on. When the VCSEL turns off, this internal parasitic capacitor discharges, keeping the VCSEL on longer, increasing the physical turn-off or fall time. The laser driver circuit compensates for the slower fall time by modulating both anode and cathode terminals of the VCSEL as the VCSEL is turned on and off. Both plates of the internal parasitic capacitor are discharged at turn off, cutting the parasitic discharge time in half. A cathode driver transistor modulates the cathode voltage while a source-follower transistor modulates the anode voltage. A modulating current may be switched using a current mirror structure. Multiple source-follower transistors may be selectable in parallel, with switches to select the total anode current, allowing for programmable compensation of the fall time.
    Type: Grant
    Filed: September 17, 2014
    Date of Patent: June 9, 2015
    Assignee: Hong Kong Applied Science & Technology Research Institute Company, Ltd.
    Inventor: Kwan Ting Ng