Optical Receiver Threshold Convergence for Low-Distortion Signals
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Solution Overview
Problem
Conventional optical receivers face challenges with high power consumption, system complexity, and pulse-width distortion due to the limitations of Automatic Gain Control (AGC) and Automatic Threshold Control (ATC) techniques, particularly in achieving stable threshold voltage convergence for high-performance audio and communication applications.
Innovation Solution
The optical receiver employs a level shifter with multiple linear subtractors to converge voltage signals to a threshold voltage, removing offsets and using a reference voltage generator to maintain a stable threshold, thereby minimizing pulse-width distortion and reducing system complexity and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If AGC-based optical receiver is used, then stability and accuracy of feedback system is improved, but device complexity and manufacturing cost increase due to offset removal technique requirements
Solution Approach 1:
The patent extracts and removes the DC offset component separately from the main signal path using a dedicated offset removal circuit. This allows the AGC feedback system to operate without being affected by DC offsets, improving stability while keeping the offset removal as a separate, manageable function rather than integrating it into the complex feedback loop.
Solution Approach 2:
The patent introduces an intermediary offset removal circuit between the optical detector and the AGC amplifier. This intermediary component handles the DC offset removal function, allowing the AGC system to focus on gain control without being complicated by offset management, thus reducing overall system complexity.
2Ease of manufacture
If ATC-based optical receiver is used, then manufacturing cost is reduced with low speed devices, but system complexity increases due to DC offset removal method and reset circuit requirements
Solution Approach 1:
The patent combines the DC offset removal function with the threshold voltage generation function in the ATC circuit. By merging these functions, the patent eliminates the need for separate offset removal circuits and reset circuits, reducing system complexity while maintaining the benefit of using low-speed devices for cost-effective manufacturing.
3Device complexity
If fixed threshold voltage is used, then device complexity is reduced, but pulse-width distortion occurs resulting in quality deterioration of digital audio signal
Solution Approach 1:
The patent implements a dynamic threshold voltage that automatically adjusts based on the received signal conditions. The threshold voltage is generated dynamically through the ATC circuit, which monitors the signal levels and adjusts the threshold accordingly. This dynamic adjustment prevents pulse-width distortion while keeping the system relatively simple by using feedback from the existing signal path.
4Reliability
If bipolar junction transistor process is used for optical receiver fabrication, then device performance is improved, but device size and power consumption increase compared to CMOS technique
Solution Approach 1:
The patent replaces the traditional bipolar junction transistor fabrication process with CMOS fabrication technology. This substitution maintains adequate device performance for optical reception while significantly reducing power consumption and device size, enabling the optical receiver to be integrated into mobile devices with strict power and size constraints.
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
This approach results in a compact, low-power optical receiver with reduced manufacturing costs and improved data reliability, capable of handling high-performance digital audio and communication standards with minimized pulse-width distortion.
Implementation Method 1
an optical detector for converting a received optical signal to a current signal
Data Source
AI summary
An optical receiver with a threshold voltage convergence and audio apparatus and communication apparatus using the optical receiver are provided. The optical receiver of the present invention includes an optical detector for converting a received optical signal to a current signal; a transimpedance amplifier for converting the current signal to a voltage signal; a level shifter for converging the voltage signal to a threshold voltage by removing an offset of the voltage signal, the level shifter comprising a plurality of linear subtractors connected in series; a reference voltage generator for generating a reference voltage in proportion to a variation of the offset of the voltage signal; and a comparator for comparing the threshold voltage and the reference voltage and generating a digital signal of a logic level according to a comparison result. The optical receiver of the present invention can compensate the shortcomings of the automatic voltage gain control and automatic threshold control techniques and reduce system complexity, thereby minimizing pulse-width distortion with a compact and low power consumption design and reducing the manufacturing costs of high performance digital interfaces.