Common-Path Digital Pre-Distortion for Multi-Antenna PA Linearity
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Solution Overview
Problem
In wireless communication systems, power amplifiers operating near the compression point introduce non-linear behavior, leading to spectral re-growth and efficiency issues, which existing technologies struggle to mitigate effectively.
Innovation Solution
A power amplifier network with a common input path splitting signals to multiple power amplifiers, each with its own power control network, and a single digital pre-distortion (DPD) processing circuit to ensure all amplifiers operate at the same compression point, applying a unified DPD function to maintain linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power amplifiers operate near the compression point to improve efficiency, then energy efficiency is improved, but non-linear behavior increases causing spectral re-growth
Solution Approach 1:
The patent applies digital pre-distortion (DPD) to the input signal before it reaches the power amplifier. The DPD circuit intentionally distorts the signal in advance to counteract the non-linear behavior that will occur in the power amplifier when operating near compression point. This preliminary anti-action ensures that the combined effect of DPD and power amplifier produces a linear output, allowing efficient operation without spectral re-growth.
2Reliability
If separate DPD circuits are used for each power amplifier to maintain linearity, then linearity is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple power amplifiers into parallel paths with a shared common input path. A single DPD circuit is placed in the common input path before the signal splits to multiple amplifier paths. This consolidation allows one DPD circuit to serve multiple power amplifiers simultaneously, reducing the total number of DPD circuits needed while maintaining linearity across all amplifiers through unified pre-distortion processing.
Solution Approach 2:
The single DPD circuit in the common input path performs a universal function for all parallel power amplifier paths. It processes the input signal once and distributes the pre-distorted signal to multiple amplifiers, making the DPD circuit multi-functional. This universal approach eliminates the need for separate DPD circuits for each amplifier, reducing overall system complexity while maintaining performance.
3Measurement precision
If multiple separate power control networks are used for each power amplifier path, then individual control precision is improved, but device complexity increases
Solution Approach 1:
The patent combines power control networks across parallel paths by placing gain control elements in the common input path. This allows a single power control network to adjust the signal level for all parallel power amplifier paths simultaneously, reducing the total number of separate power control networks needed while maintaining precise control over the overall output power and ensuring all amplifiers operate at their compression points.
Data Source
AI summary
Certain aspects of the present disclosure relate to methods and apparatus for power amplifier control. A power amplifier network includes a first path comprising a first power amplifier. The power amplifier network further includes a second path comprising a second power amplifier. The power amplifier network further includes a common input path to both the first path and the second path. The power amplifier network further includes a first power control network for controlling a first signal applied to the first power amplifier. The power amplifier network further includes a second power control network for controlling a second signal applied to the second power amplifier, wherein the first power control network is different from the second power control network.