Tunable Duplexer for Multi-Mode Front End Circuits

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Solution Overview

Problem

Current front end circuits for mobile phones are complex due to the need to support multiple frequency bands and both TDD and FDD duplexing modes, requiring a large number of filters and switches.

Innovation Solution

A front end circuit utilizing tunable duplexer filters that can switch between RX and TX modes, eliminating the need for separate switches and allowing operation in multiple frequency bands by tuning bandpass filters to specific frequency bands for FDD and TDD modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional front end circuits use separate filters and switches for TDD and FDD modes, then they can support different operational modes in different frequency bands, but the number of components increases significantly

Engineering Contradiction:

Improvesupport for multiple frequency bands and duplexing modesVSAvoidnumber of filters and switches

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies universality by designing a single bandpass filter that can function in both TDD and FDD modes. The filter is configured to operate as a receive filter, transmit filter, or both simultaneously depending on the operational mode, eliminating the need for separate dedicated filters for each duplexing type and reducing overall component count

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent implements dynamics through configurable filter settings that can be dynamically adjusted based on the operational mode. The bandpass filter's characteristics (passband frequencies, stopband frequencies) are made variable to adapt to different TDD and FDD requirements, allowing the same physical filter to serve multiple functions through reconfiguration rather than requiring static dedicated filters

Inventive Principle:

Principle #15Dynamics

2Reliability

If TDD duplexing uses switches to alternate between TX and RX modes, then signal isolation is achieved, but the device complexity and component count increase

Engineering Contradiction:

Improvesignal isolation between TX and RXVSAvoidnumber of switches

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the switching function entirely from the system by using a bandpass filter configuration that provides inherent isolation between transmit and receive paths. Instead of adding switches to alternate between modes, the solution removes the need for switching by relying on the filter's frequency-selective properties to naturally isolate TX and RX signals in TDD operation

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The bandpass filter acts as an intermediary element that provides signal isolation without requiring active switching components. By strategically positioning the filter's passband and stopband frequencies, it mediates between TX and RX signals, allowing the system to achieve isolation through passive filtering rather than active switching

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If multiple dedicated filters are used for different frequency bands and modes, then operational reliability is maintained, but manufacturing cost and device size increase

Engineering Contradiction:

Improveoperational reliability in different modesVSAvoidnumber of filter components

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent implements parameter changes by making the filter's operational characteristics variable. The bandpass and stopband frequencies are configured based on the selected operational mode (TDD or FDD), allowing the same physical filter to adapt to different frequency requirements and operational scenarios without requiring multiple dedicated filters

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

This solution reduces the number of components required, enabling efficient operation in various frequency bands and modes while preventing signal damage to RX circuits, and supports carrier aggregation with minimal components.

Implementation Method 1

a first tunable duplexer comprising a first tunable RX bandpass filter and a first tunable TX bandpass filter

Methodology Applied

Scientific EffectBandpass filtering: Filter (electronic)

Implementation Method 2

the tunable bandpass filter may comprise at least one tunable acoustic element

Methodology Applied

Scientific EffectAcoustic wave filtering: Surface Acoustic Wave

Data Source

PatentUS9948327B2Front end circuit and method of operating a front end circuit

Publication Date: 2018.04.17 SNAPTRACK INC

AI summary

The present invention concerns a front end circuit (1) which comprising a first tunable duplexer (5) comprising a first tunable RX bandpass filter (9) and a first tunable TX bandpass filter (10), wherein the first tunable duplexer (5) is configured to support a first FDD mode in a first FDD frequency band and a first TDD mode in a first TDD frequency band. Furthermore, the present invention concerns a method of operating the front end circuit.