Hybrid RF Power Amplifier Linearization Without Baseband I-Q
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Solution Overview
Problem
Conventional power amplifier systems for wideband mobile communication face challenges in achieving high linearity and efficiency due to complex nonlinear predistortion circuits, environmental fluctuations, and the need for costly and inflexible baseband I-Q signal sources, limiting their applicability and reconfigurability.
Innovation Solution
A digital hybrid mode power amplifier system utilizing adaptive digital predistortion algorithms and analog quadrature modulator compensation to linearize power amplifiers in the RF domain, enabling self-adjustment and supporting multi-modulation schemes, multi-carriers, and multi-channels, while being field-reconfigurable and independent of 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 digital processor implements predistortion algorithms that compute correction signals digitally, substituting complex analog hardware with flexible software-based processing while maintaining linearity performance.
Solution Approach 2:
The digital processor serves multiple functions: it performs predistortion correction, adapts to different modulation schemes, and adjusts to environmental variations. This multi-functional approach eliminates the need for dedicated hardware circuitries for each specific function, reducing overall device complexity.
2Loss of energy
If digital baseband predistortion with DSP is used, then power efficiency is improved, but linearity performance degrades under environmental variations
Solution Approach 1:
The patent implements a feedback mechanism where the digital processor continuously monitors the power amplifier's output and environmental conditions. Based on this feedback, the processor dynamically adjusts predistortion parameters to compensate for environmental variations such as temperature changes, maintaining stable linearity performance while preserving power efficiency gains.
Solution Approach 2:
The predistortion system transitions from static correction to dynamic adaptation. The digital processor continuously updates predistortion coefficients based on real-time environmental conditions and amplifier performance, enabling the system to maintain optimal linearity across varying operating conditions while keeping power consumption low.
3Reliability
If conventional PD schemes with baseband I-Q signal sources are used, then linearity correction is achieved, but adaptability to different standards and modulations is reduced
Solution Approach 1:
The digital predistortion system employs dynamic reconfigurability where the digital processor can be programmed with different predistortion algorithms and parameters suitable for various modulation schemes and communication standards. This software-based approach allows the same hardware platform to adapt to evolving standards without requiring hardware modifications.
Solution Approach 2:
The digital processor is designed to handle multiple modulation types and communication standards through a universal architecture. By implementing a suite of predistortion algorithms that can be selectively activated, the system provides universal linearity correction across different standards while maintaining the ability to specialize when needed.
4Measurement precision
If time-synchronization and amplitude-phase synchronization are required, then linearization accuracy is improved, but system complexity and calibration effort increase
Solution Approach 1:
The digital predistortion system incorporates self-calibration capabilities where the digital processor automatically performs time-synchronization and amplitude-phase alignment without requiring external calibration equipment or manual adjustment. The system uses built-in reference signals and algorithms to self-adjust synchronization parameters, reducing calibration complexity while maintaining high linearization accuracy.
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.