Beamforming RF Amplifiers Using Intermodulation Decorrelation

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Solution Overview

Problem

Communications satellites are limited by power efficiency, which restricts their data capacity and revenue potential, due to conventional approaches that fail to effectively utilize new nonlinear solid-state power amplifiers and digital ASIC technologies, leading to conservative estimates and increased hardware costs.

Innovation Solution

The implementation of a system that includes a beamformer to generate beamformed signals, power amplifiers to amplify these signals, and low noise amplifiers or digital power amplifiers, along with intermodulation decorrelation techniques to mitigate nonlinearities, allowing for the use of highly nonlinear components like digital amplifiers and low-resolution ADCs/DACs, thereby improving power efficiency and signal quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If conventional linear power amplifiers are used with conservative design assumptions, then system reliability is maintained, but power efficiency deteriorates

Engineering Contradiction:

Improvepower efficiencyVSAvoidsystem reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent changes the operating parameters of power amplifiers from traditional linear operation to nonlinear operation, specifically utilizing solid-state power amplifiers (SSPA) and digital amplifiers that operate in nonlinear regions. This parameter change enables significantly improved power efficiency while maintaining signal integrity through digital predistortion and beamforming techniques that compensate for nonlinear effects.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces conventional linear power amplification mechanisms with digital signal processing and nonlinear amplifier technologies. Specifically, it substitutes traditional linear amplifiers with digital amplifiers and SSPAs, and introduces digital predistortion algorithms to compensate for nonlinearities, thereby achieving higher power efficiency without sacrificing reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Use of energy by moving object

If nonlinear solid state power amplifiers are utilized, then power efficiency improves, but signal nonlinearities increase

Engineering Contradiction:

Improvepower efficiencyVSAvoidsignal nonlinearities

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by implementing digital predistortion before the signal enters the nonlinear power amplifier. The predistorter pre-compensates the signal with inverse nonlinear characteristics, so that when the signal passes through the nonlinear amplifier, the combined effect produces a linear output. This preliminary correction prevents nonlinear distortion from affecting the transmitted signal.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent introduces digital signal processing algorithms as intermediaries between the input signal and the nonlinear power amplifier. The beamformer and digital predistorter act as intermediary processing stages that prepare the signal to accommodate nonlinear amplification while maintaining signal quality. These intermediary digital processors enable the nonlinear amplifier to operate efficiently without degrading signal integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by stationary object

If advanced digital amplifiers and low-resolution ADCs/DACs are used, then power consumption reduces, but manufacturing precision requirements increase

Engineering Contradiction:

Improvepower consumptionVSAvoidcomponent precision

Core Design Contradiction:

Use of energy by stationary objectVSManufacturing precision

Solution Approach 1:

The patent changes the resolution parameter of ADCs and DACs from high-resolution to low-resolution implementations. By using lower-resolution converters (e.g., 1-4 bit instead of 16-24 bit), power consumption is dramatically reduced. The system compensates for the reduced precision through digital signal processing techniques including beamforming and predistortion, which maintain overall signal quality despite the lower converter resolution.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs low-resolution, lower-cost ADCs and DACs that consume less power, accepting that these components have lower precision. Rather than using expensive, high-resolution, high-power components, the system uses simpler, more power-efficient converters and compensates through algorithmic processing, effectively replacing precision hardware with computational solutions.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS10771145B2Power efficiency in beamforming RF systems

Publication Date: 2020.09.08 SEAKR ENGINEERING INC

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.