Circuit and method for driving a laser diode

Patent metadata

Field	Value
Publication number	US-10574026-B2
Application number	US-201815923823-A
Country	US
Kind code	B2
Filing date	Mar 16, 2018
Priority date	Mar 23, 2017
Publication date	Feb 25, 2020
Grant date	Feb 25, 2020

Abstract

A driver circuit for driving a laser diode is described herein. In accordance with a first exemplary embodiment the driver circuit includes a first electronic switch connected to an output node that is configured to be operably connected to a laser diode. The electric connection between the first electronic switch and the output node has a first inductance. The driver circuit further includes a bypass circuit that is coupled to the output node and configured to take over, when activated, the current supplied to the output node via the first electronic switch, thus magnetizing the first inductance.

First claim

We claim:

1. A driver circuit for driving a laser diode, the driver circuit comprising:
a first electronic switch connected to an output node that is configured to be operably connected to the laser diode; the electric connection between the first electronic switch and the output node having a first inductance; and
a bypass circuit coupled to the output node and configured to take over, when activated, the current supplied to the output node via the first electronic switch, thus magnetizing the first inductance.

2. The driver circuit of claim 1 , wherein the electric connection between the output node and the bypass circuit has a second inductance, which is also magnetized when the bypass circuit is active.

3. The driver circuit of claim 1 , further comprising a clamping circuit coupled to the first electronic switch configured to limit a voltage drop across the electronic switch in accordance with a clamping voltage.

4. The driver circuit of claim 1 , further comprising a clamping circuit coupled to the first electronic switch; the clamping circuit being configured, during switch-off of the first electronic switch, to delay the switch-off in order to allow the first inductance to demagnetize.

5. The driver circuit of claim 1 , further comprising a first driver coupled to a control electrode of the first electronic switch, the first driver being configured to generate a drive signal to switch the first electronic switch on an off in accordance with a first control signal.

6. The driver circuit of claim 5 , further comprising a first delay circuit coupled to the first driver and configured to delay the first control signal by an adjustable delay time.

7. The driver circuit of claim 1 , wherein the bypass circuit includes a second electronic switch connected to the output node; the electric connection between the second electronic switch and the output node having a second inductance.

8. The driver circuit of claim 7 , wherein the bypass circuit further includes a clamping circuit coupled to the second electronic switch; the clamping circuit being configured to take over current passing through the second inductance, when the second electronic switch is switched off.

9. The driver circuit of claim 7 , further comprising a second driver coupled to a control electrode of the second electronic switch, the second driver being configured to generate a drive signal to switch the second electronic switch on an off in accordance with a second control signal.

10. The driver circuit of claim 9 , further comprising a second delay circuit coupled to the second driver and configured to delay the second control signal by an adjustable delay time.

11. The driver circuit of claim 1 , further comprising a capacitor coupled between the first electronic switch and the output node, to decouple DC current passing from the first electronic switch to the output node.

12. The driver circuit of claim 11 , further comprising a third electronic switch coupled in operably parallel to the laser diode.

13. The driver circuit of claim 1 , further comprising a half-bridge including a third electronic switch and a fourth electronic switch coupled between a supply node and a ground node, the middle tap of the half-bridge forming a further output node configured to be operably coupled to the laser diode, so that the laser diode is coupled between the output node and the further output node.

14. The driver circuit of claim 13 ,
wherein the electric connection between the third electronic switch and the further output node having a third inductance; and
wherein the electric connection between the fourth electronic switch and the further output node having a fourth inductance.

15. The driver circuit of claim 14 , further comprising:
a clamping circuit coupled to the third electronic switch; the clamping circuit being configured to take over current passing through the third inductance, when the third electronic switch is switched off; and
a further clamping circuit coupled to the fourth electronic switch; the further clamping circuit being configured to take over current passing through the fourth inductance, when the fourth electronic switch is switched off.

16. A driver circuit for driving a laser diode, the driver circuit comprising:
a first and a second transistor half-bridge forming a H-bridge that has a first output node and a second output node configured to operably couple the laser diode in between, each transistor half-bridge being composed of a high-side transistor and a low-side transistor; and
control circuitry configured to:
switch on, in a pre-charging phase, the high-side and the low-side transistors of the first and the second transistor half-bridges to magnetize any inductances coupled in series to the high-side and the low-side transistors; and
switch off, in a ramp-up phase, the low-side transistor of the first transistor half-bridge and the high-side transistor of the second transistor half-bridge, thus directing current, which passes through the high-side transistor of the first transistor half-bridge and the low-side transistor of the second transistor half-bridge and through inductances coupled in series thereto, through the laser diode via the first and the second output node.

17. A method for driving a laser diode, the method comprising:
directing a first current, via a first electronic switch to an output node operably coupled to the laser diode thus magnetizing a first inductance effective between the first electronic switch and the output node;
draining the first current, by activating a bypass circuit, from the output node thud bypassing the laser diode; and
directing the first current to the laser diode via the output node by deactivating the bypass circuit.

Assignees

• Infineon Technologies Ag

Inventors

• Mignoli Franco
• Galvano Maurizio
• Logiudice Andrea

Classifications

• G01S7/484

  Transmitters · CPC title

• G01S7/4813

  Housing arrangements · CPC title

• H01S5/0607

  by varying physical parameters other than the potential of the electrodes, e.g. by an electric or magnetic field, mechanical deformation, pressure, light, temperature · CPC title

• H01S5/0428

  for applying pulses to the laser · CPC title

• H01S5/042 Primary

  Electrical excitation {; Circuits therefor (monolithically integrated laser drive components H01S5/0261)} · CPC title