Adjustable RF Transformer Bandwidth for 5G mmWave Multi-Band Coverage

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Solution Overview

Problem

The 5G millimeter wave radio frequency transceiver faces challenges in covering higher bandwidths due to variations in on-chip device parameters with process, voltage, and temperature, making it difficult to support multiple frequency bands without a multi-band switching solution.

Innovation Solution

An adjustable transformer with adjustable bandwidth is integrated into the radio frequency circuit, allowing switching between n258, n257, and n261 frequency bands by altering the impedance between nodes, and includes features like Q value enhancement circuits and differential amplifiers to improve performance and flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single link is used to process RF signals, then device complexity is reduced, but the ability to cover higher bandwidths deteriorates due to PVT variations

Engineering Contradiction:
Improvedevice complexityVSAvoidfrequency band coverage
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent applies dynamics by making the transformer bandwidth adjustable through switching between different tap points on the primary and secondary coils. This allows the RF circuit to dynamically adapt its bandwidth to cover different frequency bands (n257, n258, n261) while using a single link architecture, thereby maintaining low device complexity while improving frequency band coverage adaptability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the electrical parameters of the transformer by switching between different tap points, which alters the turns ratio and bandwidth characteristics. This parameter adjustment enables the same hardware circuit to operate across multiple 5G millimeter wave frequency bands, resolving the contradiction between using a simple single link and achieving broad frequency coverage.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If independent receive/transmit links are used for different frequency bands, then frequency band coverage is improved, but device complexity increases

Engineering Contradiction:
Improvefrequency band coverageVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements universality by designing a single RF link that can handle multiple frequency bands through the adjustable transformer. The transformer's ability to switch bandwidth characteristics makes one link perform the function of multiple dedicated links would otherwise be needed, thereby reducing device complexity while maintaining broad frequency band coverage.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

By making the transformer bandwidth dynamically adjustable via tap switching, the single RF link can adapt to different frequency bands (n257, n258, n261), effectively replacing the need for multiple static independent links. This dynamic adaptation reduces the number of required components while preserving multi-band capability.

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If bandwidth of transformer is increased to cover higher frequency bands, then frequency band coverage is improved, but performance deteriorates due to PVT variations

Engineering Contradiction:
Improvefrequency band coverageVSAvoidperformance stability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies dynamics by enabling bandwidth adjustment through tap switching, allowing the transformer to optimize its performance for each specific frequency band. Rather than using a fixed wide bandwidth that suffers from PVT variations, the system dynamically selects the appropriate bandwidth setting, thereby maintaining both broad frequency coverage and stable performance across different operating conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the transformer's electrical parameters (bandwidth, turns ratio) by switching between different tap points, allowing optimization for each frequency band. This parameter adjustment compensates for PVT variations by selecting the most appropriate configuration for current operating conditions, thereby maintaining performance stability while achieving broad frequency band coverage.

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 solution enables efficient coverage of multiple 5G millimeter wave frequency bands with reduced system complexity and cost, while maintaining desirable performance characteristics.

Implementation Method 1

the primary coil and the secondary coil are magnetically coupled

Methodology Applied
Scientific EffectMagnetic coupling: Electromagnetic Induction

Implementation Method 2

the at least one first coil is magnetically coupled to both the primary coil and the secondary coil

Methodology Applied
Scientific EffectMagnetic coupling: Electromagnetic Induction

Data Source

PatentEP3937386B1Radio frequency circuit and adjustable transformer
Publication Date: 2025.06.25 HUAWEI TECH CO LTD
  • EP3937386B1 patent drawingFigure 1~3
  • EP3937386B1 patent drawingFigure 4~5
  • EP3937386B1 patent drawingFigure 6

AI summary

This application provides a radio frequency circuit and an adjustable transformer, relates to the field of electronic technologies, and is used for signal receiving or sending in different frequency bands in a 5G millimeter wave. The radio frequency circuit includes an adjustable transformer, a first-stage amplifier, and a second-stage amplifier, the first-stage amplifier is coupled to the second-stage amplifier by using the adjustable transformer, and a bandwidth of the adjustable transformer is adjustable. When the bandwidth of the adjustable transformer is adjusted, an operating frequency band of the radio frequency circuit covers an n258 frequency band and an n257 frequency band, or the n258 frequency band and an n261 frequency band.