Laser Driver Sub-Switching Units for Uniform High-Current Pulses
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Solution Overview
Problem
Integrated laser driver circuits face limitations in switching high currents due to varying switching times of sub-switching units, making it difficult to implement required switching times and pulse shapes, especially in high-current applications.
Innovation Solution
Incorporating an energy store within each sub-switching unit to provide switching energy, connected between the supply and ground connections, which stabilizes the supply voltage and allows for quick switching of high pulse currents, and using low-impedance capacitors to minimize inductive effects and prevent interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple sub-switching units are connected in parallel to generate high pulse currents, then the total current capability is improved, but the switching time uniformity deteriorates due to different switching times of individual units
Solution Approach 1:
The laser driver circuit is divided into multiple identical sub-switching units, each capable of generating a partial pulse current. By segmenting the overall current generation task across parallel units, the circuit achieves high total current capability while each unit operates independently with consistent switching characteristics, improving overall switching time uniformity.
Solution Approach 2:
Each sub-switching unit is equipped with its own local energy storage device (capacitor) connected between the supply terminal and ground terminal. This local energy storage provides the switching energy required for each unit's switch independently, ensuring that all units switch simultaneously with uniform timing regardless of variations in other units, thereby resolving the switching time uniformity issue.
2Speed
If high pulse currents are switched rapidly, then the switching speed is improved, but the supply voltage stability deteriorates due to voltage collapse during switching
Solution Approach 1:
Energy storage devices (capacitors) are pre-charged during the non-switching period to store the switching energy required for rapid current transitions. When switching is required, this pre-stored energy is immediately available locally at each sub-switching unit, enabling fast switching without causing supply voltage collapse, thus maintaining voltage stability during high-speed operation.
3Productivity
If the switching time is reduced to achieve rapid pulse current switching, then the productivity is improved, but the pulse shape precision deteriorates
Solution Approach 1:
The circuit design allows independent optimization of switching speed and pulse shape by changing key parameters: the capacitance values of the energy storage devices, the switching thresholds, and the transistor dimensions. This enables the circuit to achieve both rapid switching (high productivity) and precise pulse shape control (high precision) simultaneously by selecting appropriate parameter values.
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
Enables the switching of high pulse currents in the ampere range quickly and reliably, with reduced switching times and improved pulse shape, while stabilizing the supply voltage and preventing interference, allowing for precise control of laser diodes in applications like LIDAR and automotive technology.
Implementation Method 1
the energy storage device is configured as at least one capacitor
Implementation Method 2
This capacitor preferably has a low impedance. Additionally, disruptive, time-limited overvoltages can be absorbed, thus reducing their propagation and harmful effects.
Implementation Method 3
it has also proven advantageous if the energy storage device is connected via a short and low-inductance connection. By using appropriately short conductors and/or large cross-sections of the conductor tracks, the energy storage device can be connected with low inductance.
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to an integrated laser driver circuit (1) for switching a pulse current (lP) for a laser diode (2) having a plurality of sub-switching units (3) for respectively generating a partial current (lT) using a switch (4) for pulsing the partial current (lT). The sub-switching units (3) for generating the pulse current (lP) are connected in parallel with one another. In the sub-switching units (3), one energy store (5) each is integrated for providing switching energy required for switching the switch (4). The invention further relates to a laser system (16) having at least one laser diode (2) and at least one integrated laser driver circuit (1).