Phase Invertible Distortion Paths for CATV Laser Compensation
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Solution Overview
Problem
Existing distortion compensation circuits in CATV systems using directly-modulated lasers are ineffective in compensating for distortion caused by non-linear elements, particularly due to the inability to change the phase of secondary paths by 180°, which affects the magnitude and sign of coefficients in Taylor series expansions, leading to incomplete compensation during operation and with changes in system parameters.
Innovation Solution
The implementation of phase invertible distortion paths in distortion compensation circuits, which include both frequency-independent and frequency-dependent distortion sub-paths, allows for controllable phase inversion of distortion products, enabling effective compensation for composite second-order (CSO) and composite triple beat (CTB) distortions by generating compensating distortion products with adjustable magnitude and phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional distortion compensation circuits are used without phase inversion capability, then the circuit structure is simpler, but the distortion compensation effectiveness deteriorates when system parameters change
Solution Approach 1:
The patent introduces controllable phase inverters in the secondary signal path that can dynamically change the phase of distortion products by 180 degrees. This dynamic phase adjustment capability allows the compensation circuit to adapt to changing system parameters and maintain effective distortion compensation under varying operating conditions, resolving the contradiction between compensation reliability and circuit complexity.
2Adaptability or versatility
If the phase of distortion products cannot be inverted, then the circuit is easier to implement, but the ability to compensate for distortion with changing coefficients deteriorates
Solution Approach 1:
The patent implements phase inversion capability by introducing controllable phase inverter elements that can change the phase parameter of distortion products by 180 degrees. This parameter change enables the circuit to adapt to varying distortion characteristics caused by changing system parameters such as temperature and operating conditions, thereby improving compensation adaptability while adding controlled complexity to the circuit structure.
3Manufacturing precision
If fixed distortion compensation is used, then the circuit is simpler, but the precision of distortion compensation deteriorates under varying operating conditions
Solution Approach 1:
The patent introduces dynamic phase inversion capability to the distortion compensation circuit, allowing the phase of distortion products to be adjusted by 180 degrees based on operating conditions. This dynamic adjustment significantly improves compensation precision under varying operating conditions while adding controlled complexity to the circuit structure through the inclusion of controllable phase inverter elements.
Data Source
AI summary
A distortion compensation circuit compensates for distortion generated by one or more non-linear elements such as a laser device and may include a primary signal path for carrying an input signal and one or more secondary signal paths for generating distortion. The distortion compensation circuit may also include one or more controllable phase inverters on at least one of the paths. For example, the secondary signal path may include a distortion generator to produce distortion products from the input signal and a signal controlled phase inverter that inverts the phase of the distortion products. The distortion generator and phase inverter may be combined as an invertible distortion generator. The phase inversion may be controlled in response to a phase inversion control signal generated based on one or more parameters such as temperature.