Digital Hybrid RF Power Amplifier Linearization Without I-Q Feedback
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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 complex nonlinear predistortion circuits, environmental fluctuations, and the need for costly and inflexible hardware, especially in systems lacking baseband I-Q signal sources.
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 capabilities 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
1Reliability
If conventional feedforward linear power amplifier with dedicated hardware circuitries is used, then linearity performance is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces conventional hardware-based predistortion circuitry with a digital signal processing approach. The predistortion function is implemented through digital algorithms that process the baseband signal before DAC conversion, eliminating the need for complex analog hardware circuitries while maintaining linearity performance.
Solution Approach 2:
The patent changes the implementation domain from analog hardware to digital processing. By performing predistortion in the digital baseband domain and using adaptive algorithms to adjust predistortion parameters, the system achieves the same linearity improvement with significantly reduced hardware complexity.
2Reliability
If conventional DSP-based predistortion with wideband feedback is used, then linearity is improved, but synchronization errors and complexity increase
Solution Approach 1:
The patent performs predistortion processing in the baseband domain before the signal is converted to analog and transmitted. By applying the predistortion function preliminarily in the digital domain, the system avoids the need for complex post-transmission synchronization and feedback alignment, simplifying the overall system while maintaining linearity.
3Measurement precision
If conventional PD schemes with baseband I-Q signal sources are used, then predistortion accuracy is improved, but adaptability to different systems decreases
Solution Approach 1:
The patent implements a universal predistortion architecture that operates in the digital baseband domain, which is common to all modern wireless communication systems. The adaptive algorithms can be configured to work with different modulation schemes and system types (base stations, repeaters, indoor coverage systems) without requiring system-specific hardware modifications, achieving both accuracy and versatility.
4Reliability
If conventional FFLPA with auxiliary PA is used, then non-linear distortion cancellation is improved, but power efficiency worsens
Solution Approach 1:
The patent extracts the predistortion function from the power amplifier stage and implements it separately in the digital baseband processing stage. This separation allows the main power amplifier to operate more efficiently without requiring an auxiliary PA for distortion cancellation, as the non-linearities are pre-compensated in the digital domain before amplification.
Data Source
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.