Multibranch Doherty Transmitter With Dynamic Phase Alignment

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Solution Overview

Problem

Existing Doherty amplifiers face inefficiencies due to complex gain fluctuations, power-dependent phase misalignment, and power loss in multiple-stage architectures, particularly in high peak-to-average power ratio (PAPR) scenarios, leading to imperfect load modulation and degraded efficiency.

Innovation Solution

A digital Doherty amplifier architecture incorporating a baseband signal processing block with digital predistortion, adaptive signal distribution, and dynamic phase alignment units, along with a predefined RF Doherty combining network, to ensure ideal current profiles and phase alignment across multiple amplifier branches.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If multiple-stage Doherty amplifier architecture is used to handle high PAPR signals, then the power amplifier can operate efficiently at backed-off power levels, but complex gain fluctuations and power-dependent phase misalignment occur between branches

Engineering Contradiction:

Improvepower amplifier efficiencyVSAvoidphase alignment stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by implementing digital predistortion and pre-computing optimal power distribution coefficients before signal amplification. The system calculates the required power distribution among multiple peaking amplifiers in advance based on the input signal characteristics, and applies phase correction predistortion to compensate for anticipated phase misalignment. This preliminary processing ensures that when the signal passes through the multiple-stage Doherty architecture, the branches remain properly aligned despite power-dependent phase variations, thereby maintaining both efficiency and phase stability.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If more peaking amplifiers are added to extend the efficient operation range, then the amplifier can handle higher PAPR signals, but device complexity and implementation cost increase significantly

Engineering Contradiction:

ImprovePAPR handling capabilityVSAvoidamplifier architecture complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements dynamics by introducing adaptive power distribution that dynamically adjusts the contribution of each peaking amplifier branch based on the instantaneous signal conditions. The system continuously monitors the input signal characteristics and recomputes the optimal power distribution coefficients in real-time, enabling the amplifier to adaptively allocate power among branches. This dynamic adaptation allows the system to achieve high PAPR handling capability with a moderate number of peaking amplifiers, avoiding the need for excessive hardware while maintaining versatility across different signal conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent applies parameter changes by digitally adjusting the power distribution coefficients and phase correction parameters based on operating conditions. Instead of adding more hardware components, the system changes the operational parameters (power split ratios, phase offsets) of existing amplifiers to optimize performance for different PAPR levels. This software-controlled parameter adjustment provides a flexible and cost-effective way to extend the efficient operation range without proportionally increasing device complexity.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If digital signal processing is implemented for phase alignment and power distribution, then phase accuracy and load modulation perfection improve, but device complexity and computational requirements increase

Engineering Contradiction:

Improvephase alignment accuracyVSAvoidsignal processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces mechanical/analog phase alignment and power distribution mechanisms with digital signal processing. Instead of using complex analog circuits for phase shifting and power splitting, the system uses digital algorithms to compute the required adjustments and applies them through digital-to-analog conversion and baseband processing. This substitution achieves high phase alignment accuracy and precise power distribution while avoiding the hardware complexity and tolerances issues associated with analog implementations. The digital approach provides programmable precision without proportional increases in physical device complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS20250357900A1Multiple Branch Transmitter

Publication Date: 2025.11.20 GHANNOUCHI FADHEL M

AI summary

A multiple branch transmitter, comprising an RF power amplifier block having at least two amplifiers, each amplifier having a respective input and respective output, each amplifier for amplifying a signal presented at the respective input, an RF combining network coupled to the respective output of each amplifier for combining signals from each respective output, and a processing block for distributing portions of an input signal amongst the respective inputs of the amplifiers, by generating two or more output signals with dynamically varying complex ratios to realize a targeted load modulation of the power amplifier block over at least a first range of an entire operable power range of the multibranch transmitter.