Resonant laser driver

1. A laser emitter circuit comprising:

a laser diode;

a driver circuit configured to generate a first drive signal; and

a resonant circuit having a resonant frequency and coupled to the driver circuit and the laser diode, wherein the first drive signal has significant energy at substantially the resonant frequency of the resonant circuit and the resonant circuit generates a continuous wave sinusoidal drive signal to drive the laser diode.

2. The laser emitter circuit of claim 1 , including:

a bias circuit coupled to the laser diode; and

wherein the resonant circuit includes:

a capacitive circuit element coupled in series to the drive circuit; and

an inductive circuit element arranged in series to the capacitive circuit element and the laser diode.

3. The laser emitter circuit of claim 2 , wherein the driver circuit is configured to generate a square wave drive signal as the first drive signal and the resonant circuit is configured to produce the continuous wave sinusoidal drive signal from the square wave drive signal.

4. The laser emitter circuit of claim 1 , including an amplitude tuning circuit configured to adjust a circuit supply of the driver circuit to adjust an amplitude of continuous wave sinusoidal drive signal.

5. The laser emitter circuit of claim 4 ,

wherein the driver circuit includes a pre-driver circuit that includes a buffer circuit to provide a square wave drive signal as the first drive signal; and

wherein the amplitude tuning circuit includes a voltage regulator circuit with a tunable output voltage provided as a circuit supply to the buffer circuit.

6. The laser emitter circuit of claim 5 , wherein the amplitude tuning circuit includes a pull up assist transistor coupled to an output of the voltage regulator circuit, wherein the pull up assist transistor is only activated during a transition of an input signal to the buffer circuit.

7. The laser emitter circuit of claim 1 , including:

a bias circuit coupled to one of a cathode or an anode of the laser diode, wherein the bias circuit includes:

a bias inductance coupled to the laser diode; and

a current mirror coupled to bias inductance.

8. The laser emitter circuit of claim 1 , wherein the resonant circuit is tunable to adjust a resonant frequency of the resonant circuit to a frequency of the first drive signal.

9. The laser emitter circuit of claim 8 , wherein the resonant circuit includes a tunable capacitance circuit.

10. The laser emitter circuit of claim 9 , wherein the tunable capacitance circuit includes multiple capacitive circuit elements and at least one switch circuit, and wherein a capacitive circuit element coupled to the at least one switch circuit is greater than the parasitic capacitances of the switch circuit when the switch circuit is in an off state.

11. A laser diode drive circuit comprising:

a resonant circuit having a resonant frequency and including an output for coupling to a laser diode, and an input; and

a driver circuit coupled to the input of the resonant circuit and configured to provide a first drive signal to the resonant circuit having significant energy at the resonant frequency of the resonant circuit, wherein the resonant circuit is configured to produce a continuous wave sinusoidal drive signal from the first drive signal and drive the laser diode with the continuous wave sinusoidal drive signal; and

a bias circuit including a bias inductance for coupling to the laser diode.

12. The laser diode drive circuit of claim 11 ; wherein the bias circuit includes a current mirror circuit including a first current mirror branch and a second current mirror branch, wherein the first current mirror branch is coupled to the bias inductance.

13. The laser diode drive circuit of claim 11 , including the laser diode, and wherein the resonant circuit includes:

a capacitive circuit element coupled in series to the driver circuit; and

an inductive circuit element arranged in series to the capacitive circuit element and the laser diode.

14. The laser diode drive circuit of claim 13 , wherein the resonant circuit is tunable to adjust a resonant frequency of the resonant circuit to a frequency of the drive signal.

15. The laser diode drive circuit of claim 11 , wherein the resonant circuit includes an inductive circuit element, and wherein at least one of the bias inductance or the inductive circuit element of the resonant circuit are implemented using one or more bond wires of an integrated circuit that includes the laser diode.

16. The laser diode drive circuit of claim 11 , including an amplitude tuning circuit configured to adjust a circuit supply of the driver circuit to adjust an amplitude of continuous wave sinusoidal drive signal.

17. The laser diode drive circuit of claim 16 , wherein the amplitude tuning circuit includes a voltage regulator circuit having a tunable output voltage provided as a circuit supply to the driver circuit.

18. The laser diode drive circuit of claim 11 , including a second drive circuit configured to generate second drive signal and a second resonant circuit coupled to the second drive circuit and having an output for coupling to the laser diode, wherein the second resonant circuit is configured to produce a second continuous wave sinusoidal drive signal from the second drive signal to drive the laser diode.

19. A method of operating a laser emitter of a time of flight sensor, the method comprising:

generating a first drive signal using a driver circuit, wherein the first drive signal has significant energy at a first signal frequency;

producing, using a resonant circuit having a resonant frequency substantially equal to the first signal frequency, a continuous wave sinusoidal drive signal from the first drive signal; and

driving a laser diode of the laser emitter using the continuous wave sinusoidal drive signal.

20. The method of claim 19 , including biasing the operating current of the laser diode using a bias inductance coupled to the laser diode and a current mirror coupled to the bias inductor.

21. The method of claim 19 , wherein the driver circuit includes a pre-driver circuit and a main driver circuit, and the method further includes adjusting a circuit supply of one of the pre-driver circuit or the main driver circuit to adjust the amplitude of the continuous wave sinusoidal drive signal.

22. The method of claim 19 , including tuning the resonant frequency of the resonant circuit to the frequency of the drive signal.