Beamforming RF Chain for Nonlinear Amplifier Power Efficiency
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Solution Overview
Problem
Conventional power optimization methods for communications satellites are limited by conservative assumptions about amplifier linearity, leading to inefficiencies in power usage and capacity, especially with the advent of new nonlinear solid-state power amplifiers and digital ASIC technologies.
Innovation Solution
The implementation of a novel RF chain architecture that includes beamforming and intermodulation decorrelation techniques to compensate for nonlinearities, allowing the use of highly nonlinear components like digital amplifiers and low-resolution ADCs/DACs, which improves power efficiency and signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional linear amplifiers are used with conservative design assumptions, then system reliability is maintained, but power efficiency deteriorates
Solution Approach 1:
The patent converts the harmful effect of amplifier nonlinearities into a beneficial outcome by using beamforming techniques to manage and exploit the nonlinear distortion products. Instead of avoiding nonlinear amplifiers, the system uses digital beamforming to steer interference away from desired signals, thereby enabling the use of highly efficient nonlinear amplifiers while maintaining system performance.
Solution Approach 2:
The patent changes the operating parameters of power amplifiers from linear mode to nonlinear/saturated mode, which dramatically improves power efficiency. By combining this parameter change with beamforming signal processing, the system maintains reliability while achieving superior power efficiency compared to conventional linear amplifier operation.
2Loss of energy
If nonlinear power amplifiers are used to improve power efficiency, then power consumption is reduced, but intermodulation distortion increases
Solution Approach 1:
The patent converts the harmful intermodulation distortion generated by nonlinear amplifiers into a manageable parameter through beamforming. By using adaptive beamforming algorithms, the system steers distortion products into specific spatial directions away from desired communication signals, thereby enabling the use of efficient nonlinear amplifiers without sacrificing signal quality.
Solution Approach 2:
The patent moves the problem of intermodulation distortion from the signal domain to the spatial domain by employing beamforming. Instead of trying to eliminate distortion in the traditional signal processing sense, the system uses spatial filtering to separate desired signals from distortion products based on their different spatial characteristics.
3Use of energy by moving object
If beamforming is implemented to manage nonlinearities, then power efficiency improves, but system complexity increases
Solution Approach 1:
The patent replaces complex hardware solutions for managing amplifier nonlinearities with digital signal processing techniques. Instead of using additional analog components or complex RF circuitry, the system uses digital beamforming algorithms to manage distortion, thereby reducing hardware complexity while maintaining power efficiency benefits.
4Ease of manufacture
If digital amplifiers and low-resolution ADCs/DACs are used, then hardware costs are reduced and power efficiency improves, but signal quality deteriorates
Solution Approach 1:
The patent converts the signal quality degradation caused by low-resolution ADCs/DACs and digital amplifiers into an acceptable outcome by using beamforming to recover signal integrity. The beamforming process in the digital domain compensates for the quantization noise and distortion introduced by low-resolution converters, thereby enabling cost-effective hardware implementations.
Data Source
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AI summary
A satellite communication system processes a plurality of input signals to generate beamformed signals, drives a plurality of nonlinear power amplifiers with the beamformed input signals to produce RF signals for transmission; and transmits the RF signals with a plurality of Tx antenna elements. Conversion to and from linear signals to and from nonlinear or digitized signals is performed. Temporal or spatial decorrelation of the beamformed signals is employed to reduce the impact of intermodulation products. In some cases the power amplifiers are nonlinear, and can be one-sided or two-sided and produce two or three distinct output levels.