Optical Receiving Circuit Gain Switching With Reset Offset Compensation
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Solution Overview
Problem
Conventional optical receiving circuits in PON systems face challenges in achieving high sensitivity and wide dynamic range due to level detection errors and waveform distortion caused by circuit delays during gain switching, especially at high speeds, leading to deteriorated waveform quality and sensitivity.
Innovation Solution
A receiving method and circuit that includes a preamplifier with a level detector and reset signal generator to detect level variations and generate a reset signal with opposite polarity, which is added to the output voltage signal, and a post amplifier with a reset signal detector to reset the offset compensator, ensuring accurate offset compensation and minimizing waveform distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If gain switching is performed in the preamplifier to widen dynamic range, then the receiving circuit can handle signals of varying levels, but circuit delay causes level detection errors and waveform distortion in the offset compensator
Solution Approach 1:
The invention applies preliminary action by detecting level variations in the preamplifier output and generating a reset signal before the offset compensator performs its compensation operation. This reset signal is added to the output voltage signal to cancel the waveform distortion caused by circuit delay, ensuring accurate level detection by the offset compensator subsequent to the gain switching operation.
2Productivity
If high speed operation is implemented to improve transmission performance, then burst data signal response is enhanced, but circuit delay increases causing deterioration in waveform quality
Solution Approach 1:
The invention converts the harmful effect of circuit delay into a beneficial correction by detecting the level variation caused by the delay and generating a reset signal with opposite polarity. This reset signal is added to the output voltage signal to cancel the waveform distortion, thereby converting the harmful delay effect into a corrected waveform that maintains high speed operation performance.
3Reliability
If offset compensation is performed after gain switching, then receiving sensitivity is improved, but level detection errors occur due to waveform variation during the switching transition
Solution Approach 1:
The invention implements feedback by having the preamplifier detect the level variation of its own output voltage signal and generate a reset signal based on this detection. This feedback mechanism ensures that the offset compensator receives an accurate level indication despite gain switching operations, thereby maintaining both receiving sensitivity and level detection accuracy.
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 highly sensitive operation with a wide dynamic range, capable of rapidly responding to burst data signals, thereby improving waveform quality and transmission characteristics without the need for expensive components like avalanche photodiodes, reducing costs and enhancing optical access system performance.
Implementation Method 1
converting an optical signal into an electronic signal by the photodiode (100)
Data Source
AI summary
A receiving method according to the present invention adjusts a level of an output voltage signal by switching a gain to be used for converting an inputted current signal to a voltage signal, in a preamplifier. Performing offset compensation on the output voltage signal in an offset compensator, in a post amplifier. Adding a reset signal, whose polarity is made opposite to a polarity of the output voltage signal, to the output voltage signal, in the preamplifier. Detecting the reset signal having added to the output voltage signal, and resetting the offset compensator by use of the detected reset signal, in the post amplifier.