Digital Hybrid RF Power Amplifier for Multi-Modulation Linearity
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Solution Overview
Problem
Conventional power amplifier systems for wideband wireless communication face challenges in achieving high linearity and efficiency due to poor power efficiency, environmental vulnerabilities, and the need for complex hardware and calibration, while digital predistortion schemes are limited by synchronization errors and require baseband I-Q signal sources, making them inflexible and costly.
Innovation Solution
A field-reconfigurable digital hybrid mode power amplifier system using adaptive digital predistortion algorithms in the RF domain, combining crest factor reduction and power efficiency boosting techniques, with self-adaptation algorithms to compensate for nonlinearities and memory effects, allowing for multi-modulation and multi-channel support without requiring baseband I-Q signal sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional feedforward linear power amplifier is used, then linearity performance is improved, but power efficiency deteriorates
Solution Approach 1:
The power amplifier is divided into a main PA and an auxiliary PA, each handling different signal components. The main PA processes the bulk signal while the auxiliary PA corrects nonlinear distortion errors, allowing each segment to operate more efficiently while maintaining overall linearity.
Solution Approach 2:
An intermediary signal processing path is introduced that captures distortion errors from the main PA, processes them through the auxiliary PA, and subtracts them from the original signal. This intermediary correction mechanism improves linearity without requiring the main PA to operate at low efficiency points.
2Measurement precision
If traditional predistortion schemes are implemented, then linearity is improved, but device complexity increases
Solution Approach 1:
The auxiliary PA is designed to perform multiple functions: it generates distortion errors, processes correction signals, and provides linearity improvement. This multi-functional approach reduces the need for separate dedicated circuits for each function, thereby reducing overall system complexity.
Solution Approach 2:
The system uses its own output signal to generate the correction needed. The auxiliary PA captures distortion errors from the main PA output and uses these same errors to create the correction signal, eliminating the need for external reference signals or complex calibration hardware.
3Use of energy by moving object
If conventional DSP-based predistortion is used, then power efficiency is improved, but adaptability to environmental changes deteriorates
Solution Approach 1:
The system implements a feedback mechanism where the auxiliary PA continuously monitors distortion errors from the main PA and adjusts its correction signal accordingly. This real-time feedback allows the system to adapt to environmental changes such as temperature variations without requiring complex recalibration procedures.
Solution Approach 2:
The correction signal from the auxiliary PA is dynamically adjusted based on the actual distortion errors observed in real-time operation. This dynamic adaptation allows the system to maintain optimal performance across varying environmental conditions, unlike static predistortion approaches.
4Measurement precision
If baseband predistortion is implemented, then linearity performance is improved, but ease of operation deteriorates due to synchronization requirements
Solution Approach 1:
The system extracts distortion errors directly from the RF output signal of the main PA, eliminating the need to work with baseband I-Q signals. This extraction approach removes the synchronization complexity associated with baseband processing while maintaining the linearity benefits of predistortion.
Solution Approach 2:
The system replaces the mechanical/baseband signal processing approach with an RF-domain approach. By working directly with RF signals in the auxiliary PA, the system eliminates the need for ADCs, DACs, and complex synchronization mechanisms required in baseband systems.
5Measurement precision
If conventional FFLPA with auxiliary PA is used, then linearity is improved, but manufacturing cost increases
Solution Approach 1:
The auxiliary PA is merged with the main PA to form an integrated power amplifier system. This merging allows shared components such as power supply, control logic, and housing, reducing the overall bill of materials and assembly costs compared to completely separate PA units.
Solution Approach 2:
The auxiliary PA performs multiple functions including distortion error generation, correction signal processing, and linearity improvement. This multi-functionality reduces the need for separate dedicated circuits and components, thereby lowering manufacturing costs despite the added functionality.
Data Source
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AI summary
A RF-digital hybrid mode power amplifier system for achieving high efficiency and high linearity in wideband communication systems is disclosed. The present invention is based on the method of adaptive digital predistortion to linearize a power amplifier in the RF domain. The present disclosure enables a power amplifier system to be field reconfigurable and support multi-modulation schemes (modulation agnostic), multi-carriers and multi-channels. As a result, the digital hybrid mode power amplifier system is particularly suitable for wireless transmission systems, such as base-stations, repeaters, and indoor signal coverage systems, where baseband I-Q signal information is not readily available.