Multi-Channel Balun Transformer for Duplexing

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Solution Overview

Problem

Existing balun designs occupy large silicon area, are not integratable for lower-frequency applications, and fail to enable duplexing operation due to capacitive coupling and additional losses from switches, limiting their efficiency and reliability in transceiver circuits.

Innovation Solution

A multi-channel integrated transformer with inductively coupled primary and secondary circuits, allowing for adjustable impedance through parallel reactive elements, eliminating the need for commutating switches and reducing capacitive coupling, enabling duplexing and various transformation ratios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple baluns are used to increase the number of output channels, then the number of channels is increased, but the silicon area occupied is doubled

Engineering Contradiction:

Improvenumber of output channelsVSAvoidsilicon area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent combines multiple balun functions into a single integrated transformer structure with multiple primary inductive circuits (I1, I1') and secondary inductive circuits (I2, I2'). This merging approach allows the device to provide multiple output channels while occupying significantly less silicon area than using separate baluns, directly resolving the contradiction between channel quantity and area occupation.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated transformer is designed with multi-functionality to serve as a multi-channel balun, impedance transformer, and channel isolator simultaneously. The structure with multiple inductively coupled circuits enables it to provide multiple output channels with different transformation ratios while maintaining compact size, thus achieving both high adaptability and small area occupation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If baluns with transmission lines are used, then impedance transformation is achieved, but the device occupies large silicon area and is not integratable for lower-frequency applications

Engineering Contradiction:

Improveimpedance transformation capabilityVSAvoidsilicon area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent replaces the traditional transmission line-based balun structure with an inductor-based integrated transformer structure. This substitution eliminates the need for long transmission lines (λ/4 or λ/2) that occupy large silicon area, while maintaining the impedance transformation capability through inductive coupling between primary and secondary circuits, making the device integratable for lower-frequency applications.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If commutating switches are used to couple power amplifier and low-noise amplifier to secondary inductive circuit, then transceiver functionality is enabled, but switch-related losses and reliability risks increase

Engineering Contradiction:

Improvetransceiver functionalityVSAvoidswitch-related reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent employs dynamic impedance transformation ratios to enable transceiver functionality without commutating switches. By adjusting the transformation ratio between primary and secondary circuits, the device can adapt to different operating modes (transmit/receive) while avoiding the reliability issues and losses associated with mechanical or electronic switches, thus maintaining high reliability while enabling transceiver functionality.

Inventive Principle:

Principle #15Dynamics

4Adaptability or versatility

If multiple baluns are placed side by side, then the number of channels is increased, but capacitive coupling between baluns causes channel imbalance

Engineering Contradiction:

Improvenumber of channelsVSAvoidchannel balance

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent merges multiple balun functions into a single integrated structure where primary inductive circuits (I1, I1') and secondary inductive circuits (I2, I2') are inductively coupled. This unified structure eliminates the capacitive coupling problems that occur when multiple baluns are placed side by side, while maintaining channel balance and providing multiple output channels simultaneously.

Inventive Principle:

Principle #5Merging (Combining)

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 reduces silicon area usage, eliminates switch-related losses, enables duplexing, and improves efficiency and reliability by allowing different transformation ratios and impedance adjustments, while minimizing capacitive coupling and switch-related risks.

Implementation Method 1

integrated transformer of the balanced-to-unbalanced type with N channels comprising, on a substrate, N inductive circuits which are mutually inductively coupled

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS9008603B2Integrated circuit comprising an integrated transformer of the “BALUN” type with several input and output channels

Publication Date: 2015.04.14 STMICROELECTRONICS FRANCE

AI summary

An integrated circuit includes an integrated transformer of the balanced-to-unbalanced type with N channels, wherein N is greater than 2. The integrated transformer includes, on a substrate, N inductive circuits that are mutually inductively coupled, and respectively associated with N channels.