BACKGROUND

Laser-based ranging systems, such as Lidar, often use a pulsed laser diode driver circuit to generate a short, high-current pulse, which is passed through a laser diode to emit a corresponding pulse of laser light. Reflected pulses of laser light are received by the Lidar system and used to determine a distance between the Lidar system and the point of reflection. Spatial resolution of Lidar systems is determined in part by the width of the pulse of laser light. Thus, it is usually desirable to generate a pulse of light having a width of about 5 ns or less. However, parasitic inductances of the pulsed laser diode driver circuit and the laser diode typically must be overcome to achieve the desired short pulse width. For example, many laser diodes have at least one bond wire which can contribute 1 nH of inductance, thereby limiting a slew rate of the current pulse unless there is very high voltage. Thus, some conventional pulsed laser diode driver circuits use a high source voltage, often greater than 40V-100V, to achieve the desired pulse width. Switching devices, such as GaN field-effect transistors (FET) are often used in conventional pulsed laser diode driver circuits as they can withstand such high voltages. However, pulsed laser diode driver circuits that use GaN technology may be more expensive, and/or may be more difficult to integrate with Silicon-based architectures.

SUMMARY

In some embodiments, a pulsed laser diode driver includes a first inductor having a first terminal and a second terminal. The first terminal of the first inductor is configured to receive a first source voltage, the first source voltage being based on a DC input voltage. A first source capacitor has a first terminal directly electrically connected to the first terminal of the first inductor to provide the first source voltage, and a second terminal electrically coupled to ground. A first bypass switch has a drain node that is directly electrically connected to the second terminal of the first inductor and a source node that is directly electrically connected to ground. A first bypass capacitor has a first terminal directly electrically connected to the drain node of the first bypass switch. A first laser diode has an anode and a cathode. The anode of the first laser diode is directly electrically connected to the second terminal of the first inductor and to the drain node of the first bypass switch. A first laser diode switch has a drain node that is directly electrically connected to the cathode of the first laser diode and a source node that is directly electrically connected to ground. The first laser diode switch and the first bypass switch are configured to control a current flow through the first inductor to produce a high-current pulse through the first laser diode, the high-current pulse corresponding to a peak current of a resonant waveform developed at the anode of the first laser diode.

In some embodiments, a pulsed laser diode driver includes an inductor having a first terminal and a second terminal. The first terminal of the inductor is configured to receive a source voltage. A source capacitor has a first capacitor terminal that is directly electrically connected to the first terminal of the inductor to provide the source voltage and a second capacitor terminal electrically coupled to a bias voltage node. A source switch has a first terminal that is directly electrically connected to a DC input voltage terminal and a second terminal that is directly electrically connected to the first capacitor terminal. The source switch is operable to charge the source capacitor when the source switch is enabled. A bypass switch has 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 the bias voltage node. A laser diode switch has a drain node that is directly electrically connected to the second terminal of the inductor and to the drain node of the bypass switch. A laser diode has an anode that is directly electrically connected to a source node of the laser diode switch and a cathode that is directly electrically connected to the bias voltage node. A bypass capacitor has i) a first terminal directly electrically connected to the second terminal of the inductor and a second terminal directly electrically connected to the bias voltage node, ii) a first terminal directly electrically connected to the anode of the laser diode and a second terminal directly electrically connected to the bias voltage node, iii) a first terminal directly electrically connected to the second terminal of the inductor and a second terminal directly electrically connected to the second capacitor terminal of the source capacitor, or iv) a first terminal directly electrically connected to the anode of the laser diode and a second terminal directly electrically connected to the second capacitor terminal of the source capacitor. The laser diode switch and the bypass switch are configured to control a current flow through the inductor 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.

In some embodiments, a pulsed laser driver includes an inductor having a first terminal and a second terminal, the first terminal being configured to receive a source voltage. A source capacitor has a first capacitor terminal directly electrically connected to the first terminal of the inductor to provide the source voltage and a second capacitor terminal electrically coupled to a bias voltage node. A source switch has a first terminal that is directly electrically connected to a DC input voltage terminal and a second terminal that is directly electrically connected to the first capacitor terminal. The source switch is operable to charge the source capacitor when the source switch is enabled. A bypass switch has 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 the bias voltage node. A laser diode has an anode and a cathode, the anode being directly electrically connected to the second terminal of the inductor and to the drain node of the bypass switch. A laser diode switch has a drain node that is directly electrically connected to the cathode of the laser diode and a source node that is directly electrically connected to the bias voltage node. A bypass capacitor has i) a first terminal directly electrically connected to the second terminal of the inductor and a second terminal directly electrically connected to the bias voltage node, ii) a first terminal directly electrically connected to the second terminal of the inductor and a second terminal directly electrically connected to the second capacitor terminal of the source capacitor, or iii) a first terminal directly electrically connected to the anode of the laser diode and a second terminal directly electrically connected to the cathode of the laser diode. The laser diode switch and the bypass switch are configured to control a current flow through the inductor 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.

In some embodiments, a pulsed laser diode driver includes multiple inductors, each inductor having a first terminal and a second terminal, the first terminal of each inductor being configured to receive a respective source voltage. The pulsed laser diode driver includes multiple source capacitors, each source capacitor corresponding to a respective inductor and having a first capacitor terminal directly electrically connected to the first terminal of that respective inductor to provide the source voltage and a second capacitor terminal electrically coupled to a bias voltage node. The pulsed laser diode driver includes multiple bypass switches, each bypass switch corresponding to a respective inductor and having a drain node that is directly electrically connected to the second terminal of that respective inductor and a source node that is directly electrically connected to the bias voltage node. The pulsed laser diode driver includes multiple laser diodes, each laser diode corresponding to a respective inductor and a respective bypass switch and having an anode and a cathode, the anode being directly electrically connected to the second terminal of that respective inductor and to the drain node of that respective bypass switch. A laser diode switch has a drain node that is directly electrically connected to the cathode of each of the laser diodes and a source node that is directly electrically connected to the bias voltage node. The pulsed laser diode driver includes multiple bypass capacitors, each bypass capacitor corresponding to a respective inductor and having a first terminal directly electrically connected to the second terminal of that respective inductor and a second terminal directly electrically connected to the bias voltage node. The laser diode switch and the multiple bypass switches are configured to control a respective current flow through each of the inductors to produce a respective high-current pulse through each of the laser diodes, each of the high-current pulses corresponding to a peak current of a resonant waveform developed at the anode of a respective laser diode.

