Pseudo-Doherty Balanced Amplifier Drive Splitting for RF Efficiency

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Solution Overview

Problem

Existing radio systems face challenges with power amplifier efficiency, output power, and linearity, particularly in multi-stage pseudo-Doherty load modulated balanced amplifiers, where drive signal optimization is complex and sub-optimal, leading to degraded performance and spectral emissions.

Innovation Solution

A multi-stage pseudo-Doherty load modulated balanced amplifier circuit with separate drive signals for each stage, utilizing current sensors and a digital splitter to estimate efficiency and adaptively optimize drive signals, enabling high efficiency over wide bandwidths and reducing saturation effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If separate drive signals are provided to each stage with adaptive optimization, then efficiency is improved by 6-10 dB per stage, but device complexity increases due to multiple current sensors and digital splitter

Engineering Contradiction:

Improveamplifier efficiencyVSAvoidcircuit complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent implements feedback by using current sensors to monitor the operating point of each amplifier stage and feeding this information to a digital splitter. The digital splitter adaptively adjusts the drive signals based on the feedback from current sensors, optimizing the efficiency of each stage dynamically. This closed-loop feedback mechanism enables the system to maintain optimal efficiency across varying operating conditions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent employs dynamic adaptation by allowing the drive signals to each amplifier stage to be independently optimized in real-time. The digital splitter modifies the amplitude and phase of drive signals dynamically based on feedback from current sensors, enabling each stage to operate at its optimal efficiency point regardless of loading conditions or signal variations.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If multi-stage configuration is used to extend high efficiency range, then efficiency range is extended, but device complexity increases due to additional stages and couplers

Engineering Contradiction:

Improveefficiency rangeVSAvoidmulti-stage configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent divides the amplifier system into multiple independent stages, each with its own drive signal optimization. By segmenting the amplifier into separate stages with individual current sensors and drive signal control, the system can optimize each stage independently, extending the overall efficiency range while managing complexity through modular architecture.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The digital splitter serves multiple functions simultaneously: it generates separate drive signals for each stage, optimizes the amplitude and phase of each drive signal, and adapts to varying operating conditions. This multi-functional component reduces the need for separate control circuits for each stage, managing complexity while achieving extended efficiency range.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Power

If Class C biasing is used for balanced amplifiers, then power output is optimized, but linearity deteriorates leading to spectral emissions

Engineering Contradiction:

Improvepower outputVSAvoidspectral emissions

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The patent converts the non-linear characteristic of Class C biased amplifiers into a benefit by using adaptive drive signal optimization. The digital splitter adjusts the amplitude and phase of drive signals to compensate for the non-linearity, transforming what would be harmful spectral emissions into controlled output. The system exploits the high efficiency of Class C operation while mitigating its non-linearity through intelligent signal control.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent dynamically changes the parameters of the drive signals (amplitude, phase, frequency) to optimize the operation of Class C biased amplifiers. By adjusting these parameters in real-time based on feedback from current sensors, the system maintains high power output while minimizing spectral emissions through precise control of the non-linear amplification process.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250293641A1Transceiver for driving load modulated balanced amplifier

Publication Date: 2025.09.18 ANALOG DEVICES INT UNLTD CO

AI summary

Aspects of this disclosure relate to methods of drive signal extraction for driving a pseudo-Doherty load modulated balanced amplifier, related circuitry to generate the drive signals, and related systems that include pseudo-Doherty load modulated balanced amplifiers. Methods can include generating test signal for a pseudo-Doherty load modulated balanced amplifier and estimating efficiency of the pseudo-Doherty load modulated balanced amplifier. The efficiency can be estimated based on an observed radio frequency signal and/or output signals from one or more current sensors associated with the pseudo-Doherty load modulated balanced amplifier. A digital splitter can be set based the estimated efficiency of the pseudo-Doherty load modulated balanced amplifier. The digital splitter can provide two or more drive signals to the pseudo-Doherty load modulated balanced amplifier.