Laser diode firing system
A laser diode firing circuit for a light detection and ranging device is disclosed. The firing circuit includes a laser diode coupled in series to a transistor, such that current through the laser diode is controlled by the transistor. The laser diode is configured to emit a pulse of light in response to current flowing through the laser diode. The firing circuit includes a capacitor that is configured to charge via a charging path that includes an inductor and to discharge via a discharge path that includes the laser diode. The transistor controlling current through the laser diode can be a Gallium nitride field effect transistor.
1. A LIDAR device, comprising:
a light emitting element; and
a gallium nitride (GaN) transistor electrically coupled to the light emitting element and an electrical power source, wherein the GaN transistor is configured to selectively allow current from the electrical power source to flow through the light emitting element in response to a control signal, causing the light emitting element to emit a pulse of light, wherein the control signal includes an initiating signal and a terminating signal, wherein the initiating signal initiates the current flow from the electrical power source through the light emitting element, wherein the terminating signal terminates the current flow from the electrical power source through the light emitting element and terminates emission of the pulse of light.
2. The LIDAR device of claim 1 , wherein the electrical power source provides a voltage across a first terminal and a second terminal of the electrical power source, wherein a first terminal of the light emitting element is electrically coupled to the first terminal of the electrical power source, wherein the GaN transistor is electrically coupled to a second terminal of the light emitting element, and wherein the GaN transistor is configured to selectively couple the second terminal of the of the light emitting element to the second terminal of the electrical power source in response to the control signal.
3. The LIDAR device of claim 2 , wherein the light emitting element is a laser diode, wherein the first terminal of the light emitting element is an anode of the laser diode, and wherein the second terminal of the light emitting element is a cathode of the laser diode.
4. The LIDAR device of claim 2 , wherein the GaN transistor is a field effect transistor (FET) having a gate configured to receive the control signal, a drain coupled to the second terminal of the light emitting element, and a source coupled to the second terminal of the electrical power source.
5. The LIDAR device of claim 1 , further comprising a driver circuit configured to provide the control signal.
6. The LIDAR device of claim 1 , wherein the initiating signal is a first voltage transition, and wherein the terminating signal is a second voltage transition.
7. The LIDAR device of claim 1 , wherein the electrical power source comprises a capacitor.
8. The LIDAR device of claim 1 , further comprising:
a photodetector configured to detect a reflected light pulse, wherein the reflected light pulse is a portion of the emitted pulse reflected from an object in an environment of the LIDAR device.
9. The LIDAR device of 8 , further comprising:
a controller configured to determine a distance to the object based on the reflected light pulse.
10. A LIDAR device, comprising:
a plurality of firing circuits, each firing circuit comprising:
a light emitting element; and
a gallium nitride (GaN) transistor electrically coupled to the light emitting element and an electrical power source, wherein the GaN transistor is configured to selectively allow current from the electrical power source to flow through the light emitting element in response to a control signal, causing the light emitting element to emit a pulse of light, wherein the control signal includes an initiating signal and a terminating signal, wherein the initiating signal initiates the current flow from the electrical power source through the light emitting element, wherein the terminating signal terminates the current flow from the electrical power source through the light emitting element and terminates emission of the pulse of light.
11. The LIDAR device of claim 10 , further comprising a driver circuit configured to apply a respective control signal to each of the firing circuits.
12. The LIDAR device of claim 10 , wherein the initiating signal is a first voltage transition, and wherein the terminating signal is a second voltage transition.
13. The LIDAR device of claim 10 , wherein the firing circuits are connected in parallel.
14. The LIDAR device of claim 10 , wherein the electrical power source comprises a capacitor.
15. A method, comprising:
providing, by a gallium nitride (GaN) transistor, a current flow through a light emitting element in response to a control signal;
emitting, by the light emitting element, a pulse of light in response to the current flow, wherein the control signal includes an initiating signal that initiates the current flow through the light emitting element and a terminating signal that terminates the current flow through the light emitting element and terminates emission of the pulse of light;
detecting a reflected light pulse, wherein the reflected light pulse is a portion of the emitted pulse reflected from an object in an environment of a LIDAR device; and
determining a time of flight of the emitted light pulse from the LIDAR device to the object in the environment and back to the LIDAR device based on the detected reflected light pulse.
16. The method of claim 15 , wherein the initiating signal is a first voltage transition, and wherein the terminating signal is a second voltage transition.
17. The method of claim 15 , wherein the control signal is applied by a driver circuit coupled to the GaN transistor.