Laser Diode Driver Circuit for High-Speed Time-of-Flight Systems
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Solution Overview
Problem
Existing light emission apparatuses with serial circuit configurations are not suitable for high-speed applications, consume high power, and produce poor optical pulses, leading to receiving issues in time-of-flight systems.
Innovation Solution
A light emission apparatus featuring a transistor, a load with a capacitor and inductor configuration that generates a driving signal for a laser diode, utilizing an AC-coupled setup to isolate DC current and enhance high-frequency performance, and incorporating a Schottky diode for DC restoration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a serial circuit configuration is used to drive the laser diode, then the circuit structure is simple, but the power consumption is high and the optical pulse quality is poor
Solution Approach 1:
The patent divides the driving circuit into two independent parallel channels: a first channel terminal connected to the anode of the laser diode and a second channel terminal connected to the cathode. This segmentation allows independent control of current flow through each terminal, enabling reduced power consumption while maintaining simple overall circuit structure.
Solution Approach 2:
The patent changes the electrical parameters at the two channel terminals independently, applying different voltage or current waveforms to each terminal. This parameter change approach enables optimization of the laser diode's operating conditions to reduce power consumption while improving optical pulse quality through differential driving.
2Device complexity
If a serial circuit configuration is used to drive the laser diode, then the circuit structure is simple, but the optical pulse quality is poor
Solution Approach 1:
By segmenting the driving circuit into two parallel channel terminals with independent control, the patent can separately optimize the electrical characteristics affecting optical pulse quality while keeping the circuit structure simple. Each terminal can be tuned independently for optimal pulse generation.
Solution Approach 2:
The patent implements dynamic control of the two channel terminals, allowing real-time adjustment of driving waveforms, amplitudes, and timing. This dynamic capability enables optimization of optical pulse quality parameters such as rise time, fall time, and pulse width without increasing circuit complexity.
3Ease of operation
If a serial circuit configuration is used, then the circuit is easy to implement, but it is not suitable for high-speed applications
Solution Approach 1:
The parallel two-channel terminal structure segments the current path, allowing independent optimization of each channel for high-speed operation. Each terminal can be designed with minimal parasitic inductance and capacitance, enabling faster switching speeds while maintaining ease of implementation.
Solution Approach 2:
The patent introduces independent driving circuits for each channel terminal as intermediary elements that can be optimized for high-speed performance. These intermediary drivers provide buffered control signals that reduce the loading effect on the laser diode, enabling high-speed modulation without complicating the overall circuit implementation.
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
The solution enables improved performance for high-speed applications by stabilizing the external supply voltage, reducing current loading, and allowing control over pulse amplitude and duration, thus enhancing the quality of optical pulses and reducing power consumption.
Implementation Method 1
a first capacitor coupled to the laser diode, configured to isolate a DC current on the first terminal of the transistor
Implementation Method 2
a laser diode configured to emit a light according to the driving signal
Data Source
AI summary
A light emission apparatus includes a transistor comprising a control terminal, a first channel terminal, and a second channel terminal, wherein the control terminal is configured to receive a modulation signal, the first channel terminal is configured to generate a driving signal according to the modulation signal, and the second channel terminal is coupled to a fixed voltage; and a load comprising: a first terminal; a second terminal, wherein the first terminal is coupled to the first channel terminal of the transistor and the second terminal is coupled to the fixed voltage; a laser diode configured to emit a light according to the driving signal; and a first capacitor coupled to the laser diode, configured to isolate a DC current on the first terminal of the transistor.