LED Driver Circuit Reducing Output Impedance for High-Speed Optical Transmission
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Solution Overview
Problem
Conventional driver circuits for light-emitting components in optical data transmission suffer from high power requirements, high output resistances, low output voltage, and electromagnetic interference, limiting switching speed and efficiency, especially in applications with limited supply voltage.
Innovation Solution
A circuit arrangement utilizing a voltage-limiting element, such as a diode or varistor, to control the operating voltage of the light-emitting component, eliminating the need for additional current paths and reducing output impedance, allowing for high-frequency operation and efficient voltage utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional driver circuits with multiple current paths are used to control light-emitting components, then current modulation capability is improved, but power consumption increases and output voltage decreases
Solution Approach 1:
The patent extracts and eliminates the unnecessary second current path (I2) and associated constant current source (K2) from the conventional circuit. By removing this redundant current path that causes power consumption without contributing to useful modulation, the invention achieves lower power consumption while maintaining adequate current modulation capability through the remaining first current path (I1) with constant current source (K1).
Solution Approach 2:
Instead of using multiple current paths in parallel as in conventional circuits, the patent inverts the approach by using a single current path with the constant current source positioned in the high-frequency signal path. This inversion allows the constant current source to directly modulate the light-emitting component without being bypassed, thereby improving power utilization efficiency.
2Measurement precision
If constant current sources are arranged in the high-frequency path, then current control precision is improved, but parasitic capacitances and voltage drop increase
Solution Approach 1:
The patent changes the operational parameters and configuration of the constant current source by positioning it directly in the high-frequency signal path connected to the light-emitting component. This parameter change allows the constant current source to operate at high frequencies while maintaining precise current control, and the use of a switching element minimizes the voltage drop across the current source, thereby reducing parasitic effects.
3Power
If additional current paths are added to increase output current, then current modulation range is improved, but output voltage and switching speed decrease
Solution Approach 1:
The patent removes the additional second current path (I2) that was intended to increase output current modulation range. By extracting this redundant path, the circuit achieves faster switching speed because there are fewer current paths to switch between, and the voltage drop is reduced, allowing higher output voltage to be maintained across the light-emitting component.
Solution Approach 2:
The patent employs periodic switching action of a switching element (such as a transistor) to modulate the current through the light-emitting component. This periodic switching allows efficient current modulation without requiring multiple parallel current paths, thereby maintaining fast switching speed while achieving the desired current modulation range through time-domain control rather than spatial-domain multiplication of current paths.
4Use of energy by moving object
If voltage-limiting elements are used to control operating voltage, then power consumption is reduced, but voltage control complexity increases
Solution Approach 1:
The patent introduces a switching element as an intermediary component between the power source and the light-emitting component. This switching element acts as a mediator that controls the operating voltage by switching the connection on and off, thereby reducing power consumption during non-active periods. The switching element simplifies voltage control compared to using complex voltage-limiting elements like diodes or varistors, as it provides binary control that is easy to implement and manage.
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 achieves low power consumption, high output voltage, and fast switching speeds by directly varying the operating voltage of the light-emitting component, reducing parasitic capacitances and electromagnetic interference, thereby enhancing the performance of optical data transmission systems.
Implementation Method 1
a voltage-limiting element, such as a diode or varistor, to control the operating voltage of the light-emitting component
Implementation Method 2
a semiconductor laser or a light-emitting diode is used as the light-emitting component E for optical data transmission
Data Source
Figure 1~2
Figure 3A~3B
Figure 4~5A
AI summary
The invention relates to a circuit arrangement (100), especially a driver circuit, and to a method for controlling at least one light-emitting component (20), of especially at least one electro-optical transducer, for example of at least one light-emitting diode (LED) or at least one laser such as e.g. at least one semiconductor laser, by switching at least one switching element (30) between at least one first switching position and a second switching position, at least one further circuit component (40; 40') being actively or additionally switched in the second switching position. The aim of the invention is to improve said arrangement and said method in such a manner that the power requirement and output impedance are as low as possible, thereby obtaining as high a frequency or switching speed and as high an output voltage as possible for the light-emitting component (20). According to the invention, the light-emitting component (20) can be controlled by varying its operating voltage.