PA VSWR Quadrant Detection for Analog-Assisted DPD Linearity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional baseband digital pre-distortion (DPD) linearized power amplifiers use a single DPD coefficient set for different power amplifier load voltage standing wave ratio (VSWR) values, which is ineffective due to the baseband's lack of knowledge about the actual VSWR at the power amplifier output, leading to unreliable linearization.
Innovation Solution
A power amplifier system with an analog-assisted digital pre-distortion (DPD) circuitry that includes detectors to coarsely measure VSWR phase and/or amplitude, generating VSWR quadrant data to assist the baseband processor in selecting appropriate DPD coefficients, thereby enhancing linear operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single DPD coefficient set is used for different VSWR values, then device complexity is reduced, but power amplifier linearity deteriorates
Solution Approach 1:
The patent segments the VSWR operating space into multiple quadrants (Q1-Q4) on the Smith Chart, with each quadrant having its own DPD coefficient set. This segmentation allows the system to select appropriate coefficients based on the current VSWR quadrant, improving linearity without requiring a single complex coefficient set to cover all conditions.
Solution Approach 2:
The patent implements dynamic selection of DPD coefficient sets based on real-time VSWR quadrant detection. The system transitions from a static single coefficient set to a dynamic multi-set architecture where the appropriate coefficient set is automatically selected based on the detected VSWR quadrant, maintaining optimal linearity across varying load conditions.
2Adaptability or versatility
If VSWR measurements are taken at the antenna, then measurement capability is provided, but measurement accuracy for PA linearization deteriorates
Solution Approach 1:
The patent introduces an intermediary VSWR detection mechanism that indirectly measures the VSWR at the power amplifier output by detecting the quadrant location on the Smith Chart. This intermediary approach bypasses the need for direct antenna VSWR measurements, providing accurate PA output VSWR information without requiring physical proximity to the antenna.
Solution Approach 2:
The patent replaces the traditional physical VSWR measurement system at the antenna with an analog-assisted digital detection system that uses signal processing and quadrant analysis. This substitution transitions from direct physical measurement to indirect computational determination, achieving accurate VSWR information at the PA output without antenna-mounted sensors.
3Reliability
If extensive memory and calibration are used for DPD, then power amplifier linearity is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent applies partial action by implementing coarse VSWR quadrant detection rather than full-precision VSWR measurement. This partial measurement approach (determining only the quadrant) is sufficient for selecting appropriate DPD coefficient sets, reducing memory requirements and calibration complexity while maintaining adequate linearity performance.
Solution Approach 2:
The patent changes the measurement parameter from precise VSWR magnitude to quadrant location classification. By transforming the continuous VSWR parameter into discrete quadrant categories, the system reduces the complexity of memory storage and calibration requirements while maintaining effective DPD performance across different operating conditions.
Data Source
AI summary
The present disclosure pertains to a power amplifier system that promotes enhanced signal linearity and overall system efficiency. The system includes a power amplifier with an amplification path for a radio frequency (RF) signal, and detector circuitry operationally linked to sample locations along this path. The detector circuitry captures and transmits signal characteristics of the RF signal. A voltage standing wave ratio (VSWR) quadrant data generator in communication with the detector circuitry generates VSWR quadrant data based on the detected signal characteristics. The baseband circuitry, comprised of a memory unit preconfigured with digital pre-distortion (DPD) coefficients and a DPD processor, controls the shaping of pre-distortion applied to the RF signal based on the VSWR data, thereby enhancing signal linearity. The components of the system interconnect and collaboratively function to optimize the performance and efficiency of the power amplifier system.