Laser Diode Driver Resonance Control for Ultra-Narrow Pulses
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Solution Overview
Problem
Conventional pulsed laser diode driver circuits face challenges in generating ultra-narrow laser pulses due to parasitic inductances and require high voltages, often using expensive GaN transistors, and are difficult to integrate with Silicon-based architectures.
Innovation Solution
The proposed pulsed laser diode driver incorporates a tunable resonant circuit with a bypass switch to generate high-current pulses, allowing for ultra-short laser pulses using Silicon-based switches and intentional inductors to overcome parasitic inductances, enabling independent pulsing of multi-channel laser diodes without bootstrap circuitry and optimizing pulse width through configurable switch timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If high source voltage (greater than 40V-100V) is used to overcome parasitic inductances, then pulse width can be reduced to achieve desired spatial resolution, but device complexity and cost increase due to requiring GaN transistors
Solution Approach 1:
The patent changes the voltage parameter from high voltage (40V-100V) to low voltage (5V) operation. This is achieved by transforming the driver architecture from a voltage-source-based approach to a current-source-based approach using an inductor in series with the laser diode, allowing ultra-narrow pulse generation without requiring high-voltage GaN transistors
Solution Approach 2:
The patent replaces the mechanical/electrical switching mechanism of GaN transistors with a different approach using an inductor-based current source and a simple switch (such as a MOSFET or even a diode). The inductor naturally limits di/dt and shapes the current pulse, substituting the need for complex high-voltage switching devices
2Duration of action of moving object
If high source voltage (greater than 40V-100V) is used to overcome parasitic inductances, then pulse width can be reduced to achieve desired spatial resolution, but manufacturing cost increases due to expensive GaN technology
Solution Approach 1:
The patent changes the voltage parameter from high voltage (40V-100V) to low voltage (5V) operation. This is achieved by transforming the driver architecture from a voltage-source-based approach to a current-source-based approach using an inductor in series with the laser diode, allowing ultra-narrow pulse generation without requiring high-voltage GaN transistors
Solution Approach 2:
The patent uses inexpensive, readily available components such as standard inductors, low-voltage MOSFETs, or even diodes instead of expensive GaN transistors. These conventional components are mass-produced and easily integrated with Silicon-based architectures, significantly reducing manufacturing cost while achieving the same ultra-narrow pulse width performance
3Duration of action of moving object
If GaN field-effect transistors are used to withstand high voltages, then desired pulse width can be achieved, but integration with Silicon-based architectures becomes more difficult
Solution Approach 1:
The patent changes the voltage parameter from high voltage (40V-100V) to low voltage (5V) operation. This is achieved by transforming the driver architecture from a voltage-source-based approach to a current-source-based approach using an inductor in series with the laser diode, allowing ultra-narrow pulse generation without requiring high-voltage GaN transistors
Solution Approach 2:
The patent creates homogeneity in the technological ecosystem by using low-voltage components that are compatible with standard Silicon-based CMOS fabrication processes. This allows the entire LiDAR system, including the driver circuit, to be manufactured using the same Silicon-based architecture, simplifying integration and enabling monolithic integration
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 approach allows for the generation of ultra-narrow laser pulses using lower input voltages, reduces design complexity and cost, and enhances integration with Silicon-based systems, while providing tunable parameters for pulse width and amplitude.
Implementation Method 1
a first laser diode having an anode and a cathode, the anode of the first laser diode being directly electrically connected to the second terminal of the inductor... the first pulse emission switch and the bypass switch are configured to control a current flow through the inductor to emit a high-current pulse through the first laser diode to thereby emit a light pulse, the high-current pulse corresponding to a peak current of a resonant waveform
Data Source
AI summary
A pulsed laser diode driver includes an inductor having a first terminal configured to receive a first source voltage provided by a source capacitor. A bypass switch has a drain node connected to a second terminal of the inductor. A laser diode has an anode connected to the second terminal of the inductor and a cathode connected to a drain node of a pulse emission switch. The pulse emission switch and the bypass switch are configured to control a current flow through the inductor to emit a high-current pulse through the laser diode to thereby emit a light pulse corresponding to a peak current of a resonant waveform developed at the anode of the laser diode. The bypass switch is enabled during emission of the high-current pulse to modify a falling edge of the high-current pulse.