Techniques for driving a laser diode in a LIDAR system
AssigneeAeva, Inc.
InventorsEric Bohannon, Garret Phillips, Bryce Bradford
Life of this patent
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Abstract
A frequency modulated continuous wave (FMCW) light detection and ranging (LIDAR) system that includes an optical source to generate light at a target frequency. The system also includes a first transistor to transmit a modulation current through a modulation path that includes the optical source and a modulation resistor. The system also includes electro optical circuitry coupled to the first transistor to produce a phase locked loop. The system also includes a second transistor to transmit a bias current through a bias path that includes the optical source and is separate from the modulation path, wherein the bias path is separate from the modulation path.
Claims19
A frequency modulated continuous wave (FMCW) light detection and ranging (LiDAR) system, comprising:
- an optical source to generate light at a target frequency;
- a first transistor to transmit a modulation current through a modulation path that includes the optical source and a modulation resistor;
- an electro optical circuitry coupled to the first transistor to produce a phase locked loop to maintain the light generated by the optical source at the target frequency, wherein the electro optical circuitry comprises a phase-frequency detector, a charge pump, and a loop filter coupled in series to a non-inverting input of an operational amplifier configured as an integrator, and wherein the inverting input of the operational amplifier is coupled to a set of ramp selection switches;
- and
- a second transistor to transmit a bias current through a bias path that includes the optical source, wherein the bias path is separate from the modulation path.
A method of operating a frequency modulated continuous wave (FMCW) light detection and ranging (LiDAR) system, comprising:
- delivering, via a modulation drive circuit, a modulated current through a light source to generate light at a target frequency, wherein the modulation drive circuit is controlled by an operational amplifier configured as an integrator;
- receiving a portion of the light into an electro-optical circuitry to produce a phase locked loop, wherein the electro-optical circuitry comprises a phase-frequency detector, a charge pump, and a loop filter that forms a closed loop with the modulation drive circuit;
- providing, by the electro-optical circuitry, a control signal to a non-inverting input of the operational amplifier to control a current level of the modulated current;
- controlling a set of ramp selection switches coupled to an inverting input of the operational amplifier to generate a signal pattern that modulates the modulated current;
- and
- delivering, via a bias drive circuit outside of the closed loop, a bias current through the light source, wherein a total current through the light source is a sum of the modulated current and the bias current.
A system for driving a laser diode, comprising:
- a first transistor to transmit a modulation current through a modulation path that includes an optical source and a modulation resistor in a source follower or emitter follower configuration;
- an electro optical circuitry coupled to the first transistor to produce a phase locked loop to maintain the light generated by the optical source at the target frequency, wherein the electro optical circuitry comprises a phase-frequency detector, a charge pump, and a loop filter coupled in series to a non-inverting input of an operational amplifier configured as an integrator, and wherein the inverting input of the operational amplifier is coupled to a set of ramp selection switches;
- and
- a second transistor to transmit a bias current through a bias path that includes the optical source.
Dependencies are inferred from the claim text.