Laser Diode Driver Circuit Using Inductive Pulse Charging
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Solution Overview
Problem
Conventional laser-diode driver circuits require high-voltage power supplies and bulky capacitors to minimize voltage sag, leading to inefficient power dissipation and increased costs, while struggling to deliver fast, narrow pulses without extensive input voltage filtering and large size.
Innovation Solution
A laser-diode driver circuit utilizing a low-voltage power supply and inductor, where the inductor is switched between electrically coupled and decoupled relationships with a charge-storage capacitor to generate current pulses on a pulse-by-pulse basis, eliminating the need for continuous high-voltage power supply and reducing power dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a conventional laser-driver circuit uses a large capacitor to minimize voltage sag, then voltage stability is improved, but device size and cost increase
Solution Approach 1:
The patent employs a dynamic switching mechanism that alternates between charging the capacitor through an inductor and discharging it to drive the laser diode. This dynamic operation allows the use of a smaller capacitor compared to static designs, as the capacitor is only needed to store energy for the pulse duration rather than continuously maintaining voltage stability.
Solution Approach 2:
The circuit operates in periodic cycles of charging and discharging the capacitor. During each cycle, the capacitor is charged to the required voltage level and then discharged to provide the laser drive pulse. This periodic operation enables smaller capacitor sizes while maintaining voltage stability during the pulse period.
2Speed
If a high-voltage power supply is used to improve pulse rise time, then speed is improved, but power dissipation and cost increase
Solution Approach 1:
The patent uses a dynamic inductor-switching mechanism that connects the inductor to the capacitor only during the charging phase and disconnects it during the laser drive phase. This dynamic operation allows the circuit to achieve fast rise times through inductive charging without requiring a continuously operating high-voltage power supply, thereby reducing power dissipation.
Solution Approach 2:
The inductor is used to pre-charge the capacitor to the required voltage level before the laser diode is driven. This preliminary charging action allows the circuit to achieve fast rise times without requiring a high-voltage power supply to be continuously active, reducing overall power dissipation.
3Manufacturing precision
If a high-voltage power supply is used to drive laser diodes with narrow pulses, then pulse width control is improved, but device complexity and cost increase
Solution Approach 1:
The patent employs dynamic switching of the inductor and capacitor connections to achieve precise pulse width control. By controlling the charging and discharging timing of the capacitor through the inductor, the circuit can generate narrow pulses with precise width control without requiring a complex high-voltage power supply system.
Solution Approach 2:
The inductor serves as an intermediary element between the power supply and the laser diode, enabling precise pulse width control through its switching characteristics. The inductor's ability to store and release energy in a controlled manner allows for precise pulse generation without requiring complex power supply circuitry.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables efficient, low-power dissipation and cost-effective high-speed driving of laser diodes with narrow pulse-width signals, suitable for optical communications and LiDAR systems, without the need for high-voltage power supplies or large capacitors.
Implementation Method 1
an inductor that is configured to store energy from the power supply
Implementation Method 2
a capacitor that is configured to receive charge from the inductor and generate a current pulse in the laser diode
Data Source
AI summary
The present disclosure is directed toward circuits for driving one or more laser diodes with a series of current pulses, where the energy required for each current pulse is generated and stored on a pulse-by-pulse basis. Laser-driver circuits in accordance with the present disclosure include a charge-storage inductor that is electrically coupled with a power supply and a charge-storage capacitor that is electrically coupled with a laser-diode string. The electrical coupling between the inductor and capacitor is controlled by one or more switches having on- and off-states that determine whether the inductor is charged by the power supply, charges the capacitor, or whether the charged capacitor generates a current pulse in the laser-diode string. By controlling the states of the switches, the energy provided to the laser-diode string can be controlled on a pulse-by-pulse basis.