Optical Receiver Signal Processing Device for QAM Phase Compensation
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Solution Overview
Problem
In optical communication systems using quadrature amplitude modulation (QAM), non-linear effects during signal transmission cause phase rotation, leading to demodulation errors, and existing compensation methods require increasing the number of non-linear compensation stages, which complicates the circuit design and increases the size of semiconductor devices.
Innovation Solution
A signal processing device and method that includes an electrical signal generation unit, a first phase compensation unit, and a distortion compensation unit, which performs dispersion compensation and phase rotation compensation in sequence, allowing for a reduced semiconductor device size without decreasing the number of non-linear compensation stages by optimizing the distribution of dispersion compensation between optical and electrical units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of non-linear compensation stages is increased to improve compensation capability, then the accuracy of signal processing is improved, but the circuit size and semiconductor device size increase
Solution Approach 1:
The patent divides the dispersion compensation function and non-linear compensation function into separate processing stages. The distortion compensation unit performs dispersion compensation in one stage, while the phase compensation unit performs non-linear compensation in another stage. This segmentation allows each unit to be optimized independently and reduces the overall circuit size compared to combining both functions in a single large circuit.
Solution Approach 2:
The patent extracts the dispersion compensation function from the non-linear compensation stage. By using a dedicated distortion compensation unit for dispersion compensation, the non-linear compensation unit can focus solely on phase rotation compensation, reducing its complexity and size while maintaining the required number of compensation stages for high accuracy.
2Reliability
If the number of non-linear compensation stages is increased to improve compensation capability, then the transmission quality is improved, but the power consumption increases
Solution Approach 1:
By segmenting dispersion compensation and non-linear compensation into separate units, the patent enables more compensation stages to be implemented with lower power consumption per stage. Each unit can be optimized for its specific function, reducing overall power requirements compared to a monolithic compensation system.
3Measurement precision
If the FFT/IFFT circuit is mounted to perform dispersion compensation, then the dispersion compensation accuracy is improved, but the mounting area and device size increase
Solution Approach 1:
The patent separates the FFT/IFFT-based dispersion compensation into a dedicated distortion compensation unit, allowing it to be implemented once with high accuracy while keeping the non-linear compensation units simpler and smaller. This segmentation enables the system to maintain high dispersion compensation accuracy without requiring large FFT/IFFT circuits in every compensation stage.
Data Source
AI summary
An optical receiver (20) includes an electrical signal generation unit (200), a first phase compensation unit (101), a distortion compensation unit (102), and a first dispersion compensation unit (400). The electrical signal generation unit (200) generates an electrical signal on the basis of received signal light. The first phase compensation unit (101) performs a phase rotation compensation process on the electrical signal generated by the electrical signal generation unit (200). The distortion compensation unit (102) performs a dispersion compensation process and a phase rotation compensation process in this order, at least once, on the electrical signal after having compensation performed thereon by the first phase compensation unit. The electrical signal generation unit (200), the first phase compensation unit (101), and the distortion compensation unit (102) are incorporated into one semiconductor device.