GaN Transistor Laser Diode Mounting for Low Parasitic Inductance
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Solution Overview
Problem
Existing LIDAR systems face challenges with high parasitic inductances due to wire bonding and standardized laser diode arrays, which degrade electrical performance and limit precise control of high-current pulses essential for accurate distance measurements.
Innovation Solution
An electronic device with a semiconductor body and strategically aligned metallizations for laser diodes, utilizing GaN transistors and resonant tank circuits to minimize parasitic inductances and enable precise control of short, high-current pulses for LIDAR applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding is used to connect laser diodes to PCB, then electrical connection is achieved, but parasitic inductance increases to approximately 1 nH
Solution Approach 1:
The patent extracts and eliminates the wire bonding connection method that introduces parasitic inductance. Instead, it uses direct soldering connections between laser diode terminals and PCB pads, removing the harmful intermediate wire bonding layer that causes approximately 1 nH of parasitic inductance.
Solution Approach 2:
The patent transitions from three-dimensional wire bonding (requiring vertical wire loops) to two-dimensional planar soldering connections on the PCB surface. This dimensional change reduces the current path length and eliminates the loop area that generates parasitic inductance, achieving connections with parasitic inductance below 0.1 nH.
2Ease of manufacture
If standardized laser diode strips are used, then manufacturing cost is reduced, but relative distances between diodes cannot be modified
Solution Approach 1:
The patent applies local quality by allowing different spacing configurations for different groups of laser diodes within the same array. Each diode or group of diodes can have optimized spacing according to specific application requirements, while still using standardized mounting techniques. This enables both cost-effectiveness and configuration flexibility.
Solution Approach 2:
The patent introduces dynamic adjustability in laser diode spacing through reconfigurable mounting structures that allow post-manufacturing adjustment of diode positions. This enables the system to adapt to different application requirements without requiring completely customized laser diode strips, maintaining cost efficiency while providing versatility.
3Measurement precision
If arrays of laser diodes are used to improve signal-to-noise ratio, then measurement performance is enhanced, but parasitic inductance increases
Solution Approach 1:
The patent merges multiple laser diodes into a closely-spaced array with unified electrical connections to the PCB. By combining the diodes into a single integrated mounting structure with shared low-inductance connection points, the system achieves high signal-to-noise ratio through multiple emitters while minimizing parasitic inductance through the unified connection approach.
Solution Approach 2:
The patent segments the electrical connection structure into individual low-inductance paths for each laser diode in the array, with each diode having its own dedicated PCB pad and soldering connection. This segmentation prevents current crowding and reduces mutual inductance effects between adjacent diodes, allowing the array to achieve high signal-to-noise ratio without the parasitic inductance penalty.
Data Source
AI summary
An electronic device is couplable to a plurality of laser diodes and includes a control switch having a drain coupled to a drain metallization and having a source coupled to a first source metallization that is electrically couplable to cathodes of the laser diodes. Each of a plurality of first switches has a drain coupled to the drain metallization and a source coupled to a respective second source metallization that is couplable to an anode of the laser diodes. The second source metallizations are aligned with one another in a direction of alignment, overlie, in a direction orthogonal to the direction of alignment, the respective sources of the first switches, and can be aligned, in a direction orthogonal to the direction of alignment, to the respective laser diodes. At least one of the sources of the first switches can be aligned, in a direction orthogonal to the direction of alignment, to the respective laser diode.