Light Receiving Circuit With Dynamic Transimpedance Against Saturation
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Solution Overview
Problem
In light data communication systems, the dynamic range of light receiving circuits is limited due to variations in light signal strength caused by changes in transmission distance, leading to signal distortion and incorrect output signals due to saturation of trans-impedance amplifiers.
Innovation Solution
A light receiving circuit design incorporating an inverting amplification circuit, a feedback circuit with resistors and capacitors, a limiter circuit, and a current mirror circuit that adjusts trans-impedance based on signal frequency and intensity, preventing saturation and ensuring stable operation across a wide dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gain of the trans-impedance amplifier is set to a high level to receive very weak signals, then weak signal reception is improved, but strong signals cause saturation and waveform distortion
Solution Approach 1:
The patent implements dynamic gain control by detecting the output signal level and automatically adjusting the trans-impedance amplifier gain accordingly. When the output signal exceeds a predetermined threshold, the gain is reduced to prevent saturation; when the signal is weak, the gain is increased to enhance reception capability. This dynamic adjustment resolves the contradiction between weak signal reception and strong signal accuracy.
Solution Approach 2:
The patent employs a feedback mechanism where the output signal from the trans-impedance amplifier is fed back to a gain control circuit. This feedback loop continuously monitors the output level and adjusts the amplifier gain in real-time, ensuring that both weak and strong signals are processed within the optimal dynamic range, thereby preventing saturation while maintaining sensitivity.
2Measurement precision
If the gain is set too high to accommodate weak signals, then weak signal detection is improved, but the trans-impedance amplifier becomes saturated with strong signals
Solution Approach 1:
The system dynamically adjusts the trans-impedance amplifier gain based on the detected signal level. For weak signals, the gain is set high to improve detection sensitivity; for strong signals, the gain is reduced to prevent saturation. This dynamic adaptation enables the system to maintain optimal performance across a wide operation range, resolving the contradiction between detection sensitivity and operational versatility.
Solution Approach 2:
The patent changes the operating parameters of the trans-impedance amplifier by dynamically adjusting the gain according to signal strength. This parameter adjustment allows the amplifier to adapt to different signal levels, maintaining both high sensitivity for weak signals and avoiding saturation for strong signals, thereby expanding the effective operation range.
3Device complexity
If a fixed gain is used in the trans-impedance amplifier, then circuit simplicity is maintained, but the dynamic range is limited
Solution Approach 1:
The patent introduces dynamic gain control mechanisms that automatically adjust the trans-impedance amplifier gain based on signal levels. While this adds some circuit complexity, it significantly expands the dynamic range, allowing the system to handle both very weak and very strong signals effectively, thus resolving the trade-off between circuit simplicity and adaptability.
Solution Approach 2:
By implementing feedback-based gain control, the system automatically adapts to different signal conditions without requiring manual intervention. The feedback mechanism monitors output levels and adjusts gain accordingly, expanding the dynamic range while maintaining reasonable circuit complexity through automated control.
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 effectively prevents signal distortion and maintains stable operation by adjusting trans-impedance and limiting output voltage, ensuring accurate signal processing from weak to strong light signals.
Implementation Method 1
a light receiving element which receives the light signal and outputs a current corresponding to the light signal
Data Source
AI summary
A light receiving circuit includes an inverting amplification circuit, a first light receiving element, a first circuit, and a charging circuit. The inverting amplification circuit includes an input terminal and an output terminal. The first light receiving element is connected between the input terminal and a reference potential terminal. The first circuit includes a first resistor, a second resistor, a third resistor and a capacitor. The first resistor second resistor connected through a connection point. The first resistor is connected between the input terminal and the connection point, and the second resistor connected between the output terminal and the connection point. The third resistor is connected between the connection point and connection node, and the capacitor is connected between the connection node and the reference potential terminal. The charging circuit connected between the power supply terminal and the connection node.