Outphasing RF Transmission Using Constant-Envelope Signal Decomposition
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Solution Overview
Problem
Existing radio frequency power amplifiers are inefficient and costly due to their linear amplification requirements, which can lead to non-linear distortions in amplified signals.
Innovation Solution
The system decomposes an input signal into multiple substantially constant-envelope components, which are then amplified using non-linear amplifiers in each outphasing path. Discrete phase control is applied to each path to define constellation points in a constant envelope diagram, optimizing a cost function for efficiency and transmission power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If linear amplifiers are used to amplify radio frequency signals, then non-linear distortions are avoided in the amplified signal, but the amplifiers become inefficient and expensive
Solution Approach 1:
The input signal is decomposed into multiple substantially constant-envelope components that can be processed separately through different outphasing paths. This segmentation allows each component to be amplified independently using efficient non-linear amplifiers while maintaining overall signal integrity through subsequent combining operations.
Solution Approach 2:
The invention transforms the signal representation by decomposing it into constant-envelope components with specific phase relationships. By changing the parameter domain from direct amplitude-phase representation to outphasing component representation, the system enables use of non-linear amplifiers without introducing distortion.
2Reliability
If linear amplifiers are used to ensure accurate signal amplification, then non-linear distortions are not created, but the cost of the amplification system increases
Solution Approach 1:
The signal is divided into multiple constant-envelope components that can be processed through separate outphasing paths with non-linear amplifiers. This segmentation enables the use of cheaper non-linear amplifier components while maintaining signal accuracy through the combining of processed components.
Solution Approach 2:
The outphasing decomposition and combination processes act as intermediary transformations that enable the use of non-linear amplifiers. These intermediary steps convert the signal into a form suitable for non-linear processing and then restore it to the original signal characteristics, avoiding the need for expensive linear amplifiers.
3Loss of energy
If non-linear amplifiers are used to improve power efficiency, then energy consumption is reduced, but non-linear distortions are introduced in the amplified signal
Solution Approach 1:
By segmenting the signal into constant-envelope components, each component can be amplified by non-linear amplifiers without introducing distortion. The constant-envelope nature of each component makes it immune to amplitude distortion from non-linear amplification, while the overall signal quality is preserved through coherent combining of the components.
Solution Approach 2:
The invention changes the signal parameter representation to constant-envelope form before non-linear amplification. This parameter transformation ensures that non-linear amplifiers operate in a regime where they do not introduce distortion, as the constant envelope protects against amplitude non-linearity effects.
4Productivity
If discrete phase control is applied in each outphasing path to define constellation points, then transmission efficiency is optimized, but the device complexity increases
Solution Approach 1:
Discrete phase control is applied locally in each outphasing path independently, with each path defining constellation points according to its specific requirements. This localized approach allows optimization of each path's phase control without requiring complex coordinated control across all paths, reducing overall system complexity.
Data Source
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AI summary
An apparatus comprising: means for decomposing an input signal to multiple substantially constant-envelope components; an outphasing path for each substantially constant-envelope component; means for discrete phase control in each outphasing path; an amplifier in each outphasing path; and means for combining output signals from the outphasing paths.