Shared-Port TDD/FDD Multiplexer for Spurious Signal Isolation

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Solution Overview

Problem

Existing multiplexers for devices supporting both TDD and FDD face interference issues due to non-linear spurious emissions from FDD transmissions affecting TDD reception, leading to increased circuit interfaces and costs, and the need for separate transmit ports complicates circuit design.

Innovation Solution

A multiplexer architecture with a shared transmit port for TDD and FDD systems, utilizing a switch and multiple TDD filters to isolate and suppress spurious signals, along with shared receive and antenna ports to reduce circuit area and improve multiplexing rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate transmit ports are provided for TDD and FDD systems, then isolation between TDD and FDD signals is improved, but device complexity and circuit area increase

Engineering Contradiction:

Improveisolation between TDD and FDD signalsVSAvoidcircuit interfaces and connection lines

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the transmit ports for TDD and FDD systems into a single shared transmit port. The multiplexer architecture allows both TDD and FDD signals to access the same transmit port through different paths, eliminating the need for separate transmit ports while maintaining signal isolation through the multiplexer's switching and filtering mechanisms.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The multiplexer acts as an intermediary device between the signal sources and the transmit port. It includes switching components and filters that mediate the signals, directing TDD and FDD signals to the appropriate paths while preventing interference between the two systems, thus maintaining isolation without requiring separate physical ports.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If multiple filters are added to suppress FDD transmit spurious emissions, then TDD reception quality is improved, but device complexity increases

Engineering Contradiction:

ImproveTDD reception qualityVSAvoidfilter group structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The multiplexer is designed with multi-functionality, integrating both TDD and FDD signal processing capabilities within a single device. The filter group includes filters that serve multiple purposes: suppressing FDD transmit spurious emissions during TDD reception, and managing TDD signals during transmission, thereby reducing the need for separate dedicated filters for each function.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The multiplexer employs dynamic switching mechanisms that adapt the filter configurations based on the operational mode (TDD transmit/receive or FDD transmit/receive). This dynamic reconfiguration allows the same filter group to effectively suppress spurious emissions and manage signals in different modes without requiring permanent separate filter sets, thus managing complexity through adaptability.

Inventive Principle:

Principle #15Dynamics

3Productivity

If a switch is added for TDD transmit/receive switching, then multiplexing rate is improved, but device complexity increases

Engineering Contradiction:

Improvemultiplexing rateVSAvoidswitch and connection structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The multiplexer segments the signal paths into distinct TDD and FDD channels within the shared transmit port architecture. The switch components are strategically positioned to segment and route signals based on the operational mode, enabling high multiplexing rates by efficiently managing signal separation and switching without requiring excessive complex interconnection structures.

Inventive Principle:

Principle #1Segmentation

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 ensures reliable operation of both TDD and FDD systems by reducing circuit connections and area, lowering production costs, and enhancing multiplexing rates while maintaining isolation between TDD and FDD signals.

Implementation Method 1

The filter group includes a FDD transmit filter, an FDD receive filter

Methodology Applied

Scientific EffectFrequency selective filtering: Filter (electronic)

Implementation Method 2

a first TDD filter, and a second TDD filter

Methodology Applied

Scientific EffectFrequency selective filtering: Filter (electronic)

Data Source

PatentUS20250279794A1Multiplexer and communication device

Publication Date: 2025.09.04 HUAWEI TECH CO LTD

AI summary

In one example, a multiplexer includes a transmit port, at least one receive port, at least one antenna port, a filter group, and a switch. A fixed end and a first free end of the switch are respectively connected to a first TDD filter and an output end of a second TDD filter in the filter group, a second free end is connected to one of the at least one receive port. The transmit port is connected to an input end of an FDD transmit filter and an input end of the second TDD filter, an output end of an FDD receive filter in the filter group is connected to one of the at least one receive port. An output end of the FDD transmit filter, an input end of the FDD receive filter, and the first TDD filter are connected to one of the at least one antenna port.