Dynamic supply voltage control circuit for laser diode

A system for controlling a laser diode, the system comprising:

• a first voltage source coupled to a first supply rail and configured to generate a first supply voltage;
• a second voltage source coupled to a second supply rail and having a control input, where the second voltage source is configured to generate a second supply voltage, where a voltage level of the second supply voltage is determined by a control signal at the control input of the second voltage source, and where the system is configured for the second supply rail to be coupled to a cathode of the laser diode;
• a current source having an input and an output, where the input of the current source is coupled to the first supply rail, the current source is configured to generate an operating current at the output of the current source, and the system is configured for the output of the current source to be coupled to an anode of the laser diode;
• a voltage sensor having an input and an output, where the system is configured for the input of the voltage sensor to be coupled to the anode of the laser diode;
• and
• a controller having a first input and an output, where the first input of the controller is coupled to the output of the voltage sensor, the output of the controller is coupled to the control input of the second voltage source, and the controller is configured to:
• measure a first measured voltage level of an operating voltage at the anode of the laser diode sensed by the voltage sensor,
• determine a junction operating temperature of the laser diode based on a first current level of the operating current and the first measured voltage level of the operating voltage, and
• generate a control signal at the output of the controller that adjusts the voltage level of the second supply voltage based on an operating characteristic curve corresponding to the junction operating temperature.

A method for controlling a Light Emitting Diode (LED) for illuminating a rendering of content of video data on a display screen, the LED comprising an anode and a cathode, the method comprising:

• generating a first supply voltage at an input of a first current source comprising a current output coupled to the anode of the LED, wherein the first supply voltage is generated by a first voltage source comprising an input coupled to a ground node;
• generating a second supply voltage at the cathode of the LED, wherein the second supply voltage is generated by a second voltage source comprising an input coupled to the ground node, wherein a voltage level of the second supply voltage is variable and the second supply voltage is applied to cathode of the LED;
• generating an operating current that is applied to the anode of the LED;
• monitoring an output voltage at the anode of the LED;
• detecting one or more peaks in the output voltage at the anode of the LED at a predetermined sample rate;
• and
• adjusting the voltage level of the second supply voltage in response to a detection of a new peak voltage reading to avoid saturation of the LED, wherein the second supply voltage is a negative supply voltage to provide sufficient compliance for the LED to emit light.