Coupler Balun Active Load Modulation for Wideband mm-Wave PAs

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Solution Overview

Problem

Current millimeter-wave (mm-Wave) power amplifier architectures face challenges in supporting wideband operation, maintaining high power backoff efficiency, and achieving excellent linearity, especially when dealing with complex modulations and limited carrier bandwidth.

Innovation Solution

A wideband coupler balun system with a load modulated power amplifier is introduced, comprising coupled line couplers, a differential main power amplifier, and an auxiliary power amplifier. This system allows for the modulation of load impedance based on the current ratio between the differential and auxiliary power amplifiers, enhancing power backoff efficiency and linearity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If Doherty PA architecture is used to enhance power backoff efficiency, then power backoff efficiency is improved, but bandwidth is constrained due to impedance inverters

Engineering Contradiction:

Improvepower backoff efficiencyVSAvoidbandwidth

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The PA is divided into a main PA and an auxiliary PA that operate independently but cooperatively. The main PA handles the primary signal while the auxiliary PA provides supplemental power and impedance modulation, allowing each segment to be optimized for different functions rather than requiring a single broadband impedance inverter

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The auxiliary PA dynamically modulates the load impedance seen by the main PA through active load modulation. This dynamic impedance control replaces the static impedance inverter in Doherty architectures, enabling adaptive impedance transformation across a wider bandwidth while maintaining power backoff efficiency

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If Outphasing PA architecture is used to support wide bandwidth, then bandwidth is improved, but modulation speed is limited and baseband computation overhead increases

Engineering Contradiction:

ImprovebandwidthVSAvoidbaseband computation overhead

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The balun and power combining functions are merged into a single integrated structure. The coupled-line network simultaneously performs differential-to-single-ended conversion and power combining, eliminating the need for separate baseband processing of outphasing signals and reducing computational overhead

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If current mm-Wave PA architectures are used to maintain linearity through dynamic range, then linearity is improved, but power backoff efficiency deteriorates

Engineering Contradiction:

ImprovelinearityVSAvoidpower backoff efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The auxiliary PA receives feedback about the main PA's operating conditions and dynamically adjusts its output to modulate the load impedance. This feedback mechanism enables the system to maintain optimal load conditions for linearity while improving power backoff efficiency through active impedance control

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically changes the load impedance parameter seen by the main PA through active load modulation. By adjusting the impedance parameter in real-time based on operating conditions, the system maintains linearity across different power levels while improving power backoff efficiency

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The proposed system achieves wideband operation with improved power backoff efficiency and linearity, effectively addressing the limitations of existing mm-Wave power amplifier architectures.

Implementation Method 1

the first coupled line coupler and the second coupled line coupler can be electrically connected in series

Methodology Applied

Scientific EffectCoupled line coupling:

Implementation Method 2

the auxiliary power amplifier, when powered on, can be configured to modulate a load impedance for the differential main power amplifier

Methodology Applied

Scientific EffectActive load modulation:

Data Source

PatentUS20250158571A1Broadband coupler-based balun continuous active load modulation power amplifier

Publication Date: 2025.05.15 GEORGIA TECH RES CORP

AI summary

The present disclosure provides a system for a wideband coupler balun with a load modulated power amplifier wherein the system can comprise a first port, a second port, a differential port, a differential main power amplifier, and an auxiliary power amplifier. The first port can be electrically connected to a first coupled line coupler. The second port can be electrically connected to a second coupled line coupler. The differential port can be electrically connected to the first and second coupled line coupler. The differential main amplifier can be configured to be electrically connected to the differential port. The auxiliary power amplifier can be configured to be electrically connected to the first port.