Chip-on-Chip Laser Diode Module for LIDAR
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Solution Overview
Problem
LIDAR systems face challenges in achieving high radiant power for long measurement ranges while ensuring laser pulses are short enough to be safe for human eyes, requiring driver electronics that can switch laser diode load current with extremely short rise and fall times, which is difficult due to high inductance in the current path.
Innovation Solution
The integration of a laser diode module with a semiconductor die including an electronic switch and a laser diode, using chip-on-chip connecting technology, lead frames, and capacitors to reduce parasitic inductance, allowing for faster switching and higher peak currents within shorter times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the radiant power of the laser is increased to extend measurement range, then the measurement range is improved, but the pulse duration must be shortened to ensure eye safety, which increases the difficulty of switching speed
Solution Approach 1:
The patent combines the laser diode, electronic switch, and driver electronics into a single integrated semiconductor die. This merging eliminates separate connection paths and reduces parasitic inductance, enabling the switch to respond faster to drive the laser diode with the required short rise and fall times while maintaining high radiant power for extended measurement range
Solution Approach 2:
The patent changes the electrical parameters of the driving circuit by integrating the electronic switch directly with the laser diode on the same semiconductor die. This integration fundamentally alters the inductance and resistance characteristics of the current path, enabling extremely fast switching speeds necessary for generating short laser pulses with high peak power
2Object-affected harmful factors
If the pulse width is shortened to limit radiant energy for eye safety, then the safety is improved, but the peak power must be increased to maintain measurement range, which requires faster switching
Solution Approach 1:
The integration of the electronic switch and laser diode on the same semiconductor die enables the circuit to deliver extremely high peak currents for very short durations. The reduced parasitic inductance allows the switch to rapidly charge and discharge the laser diode, generating the high peak power needed for long-range measurements while keeping pulse widths short enough to limit total energy and ensure eye safety
3Duration of action of moving object
If driver electronics are used to switch laser diode current with extremely short rise and fall times, then the pulse duration is reduced for safety, but the inductance in the current path prevents achieving sufficiently fast switching
Solution Approach 1:
The patent merges the electronic switch and laser diode into a single integrated semiconductor device, eliminating the need for external connection paths that would introduce parasitic inductance. This integration dramatically reduces the inductance in the current path, enabling the electronic switch to achieve the extremely short rise and fall times necessary for generating short laser pulses while maintaining simple device architecture
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 configuration significantly reduces effective inductance, enabling the laser diode module to achieve the necessary peak current with shorter rise times, enhancing the measurement range while ensuring safety by limiting pulse energy.
Implementation Method 1
The second semiconductor die is bonded on the first semiconductor die using a chip-on-chip connecting technology to provide electrical connection between the electronic switch and the laser diode
Data Source
AI summary
A laser diode module is described herein. In accordance with a first exemplary embodiment, the laser diode module includes a first semiconductor die including at least one electronic switch, and a second semiconductor die including at least one laser diode. The second semiconductor die is bonded on the first semiconductor die using a chip-on-chip connecting technology to provide electrical connection between the electronic switch and the laser diode.