Polyphase Digital Pre-Distortion for Low-Complexity PA Linearization
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Solution Overview
Problem
Current digital pre-distortion (DPD) technologies in radio transmitters face challenges in efficiently linearizing power amplifiers over large bandwidths with minimal sample rate requirements, often requiring complex optimization and significant hardware resources, which can be burdensome and not feasible on legacy hardware.
Innovation Solution
The implementation of an enhanced polyphase DPD structure that simplifies the system by severing interconnections between phases, allowing each DPD block to be dependent only on its own phase, and using a sub-sampled output filter to reduce complexity and improve modeling accuracy without extensive optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex optimization and significant hardware resources are used for DPD, then linearization accuracy over large bandwidth is improved, but device complexity and hardware feasibility deteriorate
Solution Approach 1:
The patent applies segmentation by dividing the signal processing into polyphase components and separating memoryless nonlinearity compensation from dynamic nonlinearity compensation. This allows the system to achieve accurate linearization over large bandwidths by processing separate phases independently, reducing the overall computational complexity and hardware requirements while maintaining high linearization accuracy.
Solution Approach 2:
The patent implements local quality by making each DPD block dependent only on its own phase rather than requiring full interconnections between all phases. This localized approach reduces the complexity of inter-phase dependencies while maintaining effective linearization performance for each phase, thereby simplifying the overall hardware structure.
2Measurement precision
If high sample rate is used for DPD processing, then linearization performance is improved, but processing speed and hardware resource requirements worsen
Solution Approach 1:
The patent uses segmentation to divide the high-rate signal processing into multiple polyphase components processed at lower rates. By separating the signal into phases that can be processed independently at reduced sample rates, the system achieves the same linearization performance as high-rate processing would provide, thereby reducing the actual sample rate requirements and associated hardware resource demands.
3Measurement precision
If interconnections between phases are maintained, then modeling accuracy is improved, but system complexity increases
Solution Approach 1:
The patent applies local quality by making each DPD block dependent only on its own phase input rather than requiring inputs from all phases. This localized dependency structure reduces the number of interconnections and computational operations required while maintaining effective modeling accuracy for each phase, thereby simplifying the overall system complexity.
Solution Approach 2:
The patent extracts and compensates for memoryless nonlinearity separately from dynamic nonlinearity. By removing the memoryless component first and handling it independently, the remaining dynamic nonlinearity can be processed with simpler inter-phase relationships, reducing overall system complexity while maintaining comprehensive modeling accuracy.
Data Source
AI summary
Systems, methods, apparatuses, and computer program products for an enhanced polyphase digital pre-distortion (DPD) structure in a radio transmitter. A method may include creating a combined pre-distorted component by combining each of the pre-distorted polyphase components. Each of the plurality of pre-distorted polyphase components are single phase dependent. Further, the method may include feeding the combined pre-distorted component to an output filter to form a pre-distorted transmission signal. The method may also include generating an output signal by applying the pre-distorted transmission signal to the power amplifier to generate an output signal.