Balanced SAW Antenna Duplexer for Direct RF Module Integration

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Solution Overview

Problem

Conventional antenna duplexers have unbalanced terminals, which prevent direct connection with semiconductor devices having balanced terminals and are prone to noise issues like crosstalk, limiting their performance and size reduction.

Innovation Solution

An antenna duplexer design with either a balanced or unbalanced terminal connected to a longitudinal mode coupled surface acoustic wave filter, allowing direct connection to balanced semiconductor devices without baluns, using ladder type filters and phase shifters for efficient balanced-unbalanced conversion and improved frequency response.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional unbalanced terminals are used in antenna duplexers, then the device structure is simple, but direct connection to balanced semiconductor devices is prevented and noise susceptibility increases

Engineering Contradiction:

Improvecompatibility with balanced semiconductor devicesVSAvoidterminal structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies balanced terminals instead of conventional unbalanced terminals in the antenna duplexer structure. This inversion of the traditional terminal type enables direct connection to balanced semiconductor devices while maintaining the overall simplicity of the device structure, thus resolving the contradiction between adaptability and complexity.

Inventive Principle:

Principle #13The other way round (Inversion)

2Object-affected harmful factors

If unbalanced terminals are used in antenna duplexers, then the device size can be reduced, but noise susceptibility such as crosstalk increases

Engineering Contradiction:

Improvenoise susceptibilityVSAvoiddevice size

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The patent switches from unbalanced to balanced terminals, which reduces noise susceptibility including crosstalk. While balanced terminals traditionally imply larger size, the integration with longitudinal mode coupled SAW filters enables compact implementation, thus resolving the contradiction between noise immunity and device size.

Inventive Principle:

Principle #13The other way round (Inversion)

3Adaptability or versatility

If balanced terminals are implemented in antenna duplexers, then direct connection to balanced semiconductor devices is enabled, but additional components like baluns are required

Engineering Contradiction:

Improvedirect connection capabilityVSAvoidcomponent quantity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The longitudinal mode coupled SAW filter is designed to perform multiple functions simultaneously: it provides frequency selectivity, impedance transformation, and directly interfaces with balanced terminals. This multi-functionality eliminates the need for separate balun components, enabling direct connection to balanced semiconductor devices without increasing overall device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Reliability

If conventional antenna duplexers with unbalanced terminals are used, then the circuit structure is simple, but performance is limited by noise and connection compatibility

Engineering Contradiction:

Improvesignal-to-noise characteristicsVSAvoidfilter structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs longitudinal mode coupled SAW filters which utilize specific acoustic wave propagation parameters to achieve superior frequency selectivity and noise rejection. By optimizing the coupling parameters and resonator characteristics, the filter provides enhanced signal-to-noise characteristics while maintaining a relatively simple integrated structure suitable for modern RF modules.

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

Enables direct connection to balanced semiconductor devices, reduces size, improves signal-to-noise characteristics, and enhances power durability, achieving compact and high-performance RF modules and communication apparatuses.

Implementation Method 1

the balanced type terminal is connected to a longitudinal mode coupled surface acoustic wave filter

Methodology Applied

Scientific EffectSurface acoustic wave: Surface Acoustic Wave

Implementation Method 2

longitudinal mode coupled surface acoustic wave filter

Methodology Applied

Scientific EffectAcoustic wave coupling:

Implementation Method 3

the transmission filter and the receiving filter includes surface acoustic wave resonators or film bulk acoustic resonators

Methodology Applied

Scientific EffectAcoustic resonance: Resonance

Data Source

PatentUS7446629B2Antenna duplexer, and RF module and communication apparatus using the same

Publication Date: 2008.11.04 SKYWORKS PANASONIC FILTER SOLUTIONS JAPAN

AI summary

One of plurality of transmission terminals connected to a transmission filter and a receiving terminal connected to a receiving filter is a balanced type terminal, and another is an unbalanced type terminal. The transmission filter and the receiving filter includes surface acoustic wave resonators or film bulk acoustic resonators. The balanced type terminal is connected to a longitudinal mode coupled surface acoustic wave filter.