Auto flux timing for current resonant laser diode driver

Patent metadata

Field	Value
Publication number	US-12438338-B2
Application number	US-202217937625-A
Country	US
Kind code	B2
Filing date	Oct 3, 2022
Priority date	Oct 3, 2022
Publication date	Oct 7, 2025
Grant date	Oct 7, 2025

Abstract

A pulsed laser diode driver includes a source capacitor that receives a refresh current at a first terminal and develops a source voltage therefrom. A first terminal of an inductor is connected to the first terminal of the source capacitor. A second terminal of the inductor is connected to an anode of a laser diode and a bypass capacitor. One or more switches are configured to control a current flow through the inductor. A timing and control circuit is configured to receive the source voltage and to generate one or more gate driver signals to control the switches to produce a high-current pulse through the laser diode. The high-current pulse corresponds to a peak current of a resonant waveform developed at the anode of the laser diode. A timing of the one or more gate driver signals is based on a voltage level of the source voltage.

First claim

What is claimed is:

1. A pulsed laser diode driver comprising:
a source capacitor having i) a first terminal configured to receive a refresh current and to develop a source voltage therefrom, and ii) a second terminal electrically coupled to ground;
an inductor having a first terminal that is directly electrically connected to the first terminal of the source capacitor;
a laser diode having an anode and a cathode, the anode being directly electrically connected to a second terminal of the inductor;
a bypass capacitor having a first terminal directly electrically connected to the second terminal of the inductor;
one or more switches configured to control a current flow through the inductor; and
a timing and control circuit configured to receive the source voltage and to generate one or more gate driver signals to control the one or more switches to produce a high-current pulse through the laser diode, the high-current pulse corresponding to a peak current of a resonant waveform developed at the anode of the laser diode, a timing of the one or more gate driver signals being based on a voltage level of the source voltage.

2. The pulsed laser diode driver of claim 1 , wherein:
the timing and control circuit is configured to generate the one or more gate driver signals to control the one or more switches to produce the high-current pulse through the laser diode when the voltage level of the source voltage is about zero volts.

3. The pulsed laser diode driver of claim 1 , wherein:
a second terminal of the bypass capacitor is directly electrically connected to ground.

4. The pulsed laser diode driver of claim 1 , wherein:
the one or more switches include a laser diode switch; and
the cathode of the laser diode is directly electrically connected to a drain node of the laser diode switch.

5. The pulsed laser diode driver of claim 1 , wherein:
a second terminal of the bypass capacitor and the cathode of the laser diode are both directly electrically connected to the first terminal of the inductor.

6. The pulsed laser diode driver of claim 1 , wherein the timing and control circuit comprises:
a voltage comparison circuit to generate a comparison signal based on a comparison between the voltage level of the source voltage and a threshold voltage; and
a switch timing control circuit to receive the comparison signal and to generate the one or more gate driver signals to control the one or more switches to produce the high-current pulse through the laser diode based on a state of the comparison signal.

7. The pulsed laser diode driver of claim 6 , wherein:
the threshold voltage is generated by a threshold voltage generator circuit comprising a bandgap voltage reference circuit.

8. The pulsed laser diode driver of claim 7 , wherein:
the threshold voltage is about 1.2 volts.

9. The pulsed laser diode driver of claim 6 , wherein:
the one or more switches comprise a bypass switch having a drain node that is directly electrically connected to the second terminal of the inductor and a source node that is directly electrically connected to ground;
the one or more gate driver signals comprise a bypass switch gate driver signal to control the bypass switch; and
the switch timing control circuit disables the bypass switch using the bypass switch gate driver signal to produce the high-current pulse through the laser diode upon determining, based on the comparison signal, that the voltage level of the source voltage is less than the threshold voltage.

10. The pulsed laser diode driver of claim 1 , wherein:
the one or more switches comprise a discharge switch having a drain node that is electrically coupled to the first terminal of the source capacitor and a source node that is directly electrically connected to ground; and
the one or more gate driver signals comprise a discharge switch gate driver signal to control the discharge switch.

11. A pulsed laser diode driver comprising:
a source capacitor having i) a first terminal configured to receive a refresh current and to develop a source voltage therefrom, and ii) a second terminal electrically coupled to ground;
an inductor having a first terminal that is directly electrically connected to the first terminal of the source capacitor;
a laser diode having an anode and a cathode, the anode being directly electrically connected to a second terminal of the inductor;
a bypass capacitor having a first terminal directly electrically connected to the second terminal of the inductor;
a bypass switch having a drain node that is directly electrically connected to the second terminal of the inductor and a source node that is directly electrically connected to ground, the bypass switch being configured to control a current flow through the inductor; and
a timing and control circuit configured to receive the source voltage, and based on determining that a voltage level of the source voltage is less than a threshold voltage, to disable the bypass switch to produce a high-current pulse through the laser diode, the high-current pulse corresponding to a peak current of a resonant waveform developed at the anode of the laser diode.

12. The pulsed laser diode driver of claim 11 , wherein:
a second terminal of the bypass capacitor is directly electrically connected to ground.

13. The pulsed laser diode driver of claim 11 , wherein:
the pulsed laser diode driver further comprises a laser diode switch; and
the cathode of the laser diode is directly electrically connected to a drain node of the laser diode switch.

14. The pulsed laser diode driver of claim 11 , wherein:
a second terminal of the bypass capacitor and the cathode of the laser diode are both directly electrically connected to the first terminal of the inductor.

15. The pulsed laser diode driver of claim 11 , wherein the timing and control circuit comprises:
a voltage comparison circuit to generate a comparison signal based on a comparison between the voltage level of the source voltage and the threshold voltage; and
a switch timing control circuit to receive the comparison signal and to generate one or more gate driver signals to control the bypass switch based on a level of the comparison signal.

16. The pulsed laser diode driver of claim 15 , wherein:
the threshold voltage is generated by a threshold voltage generator circuit comprising a bandgap voltage reference circuit.

17. The pulsed laser diode driver of claim 16 , wherein:
the threshold voltage is about 1.2 volts.

18. The pulsed laser diode driver of claim 11 , wherein:
the pulsed laser diode driver further comprises a discharge switch having a drain node that is electrically coupled to the first terminal of the source capacitor and a source node that is directly electrically connected to ground; and
the timing and control circuit is further configured to generate a discharge switch gate driver signal to control the discharge switch.

Assignees

• Silanna Asia Pte Ltd

Inventors

• Colles Joseph H
• Rosenbaum Steven E
• Molin Stuart B

Classifications

• H01S5/0261

  Non-optical elements, e.g. laser driver components, heaters (H01S5/0265 takes precedence) · CPC title

• H01S5/06825

  Protecting the laser, e.g. during switch-on/off, detection of malfunctioning or degradation · CPC title

• H01S5/06216

  Pulse modulation or generation · CPC title

• H01S5/06808

  by monitoring the electrical laser parameters, e.g. voltage or current · CPC title

• H01S5/4025

  Array arrangements, e.g. constituted by discrete laser diodes or laser bar (H01S5/42 takes precedence) · CPC title