GaAs FET Switch Module for Multi-System Signal Isolation

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Solution Overview

Problem

Existing high-frequency modules for transmitting and receiving multiple communication signals using a single antenna face challenges in minimizing size, cost, and signal loss due to the need for numerous circuit elements and inadequate signal isolation, particularly when using diode switch circuits or expensive GaAs IC switches.

Innovation Solution

A high-frequency module utilizing an FET switch with multiple signal input-output portions and diplexers to securely switch and separate transmission-reception signals from different communication systems, minimizing circuit elements and signal loss while ensuring adequate isolation between signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If diode switch circuits are used to switch transmission and reception signals in multiple communication systems, then signal switching functionality is achieved, but the number of circuit elements increases and the module size becomes large

Engineering Contradiction:

Improvesignal switching functionalityVSAvoidnumber of circuit elements

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines multiple diode switch circuits into a single integrated switch circuit that can handle multiple communication systems (GSM, DCS, PCS) simultaneously. The switch circuit uses a small number of diodes to achieve multi-functionality by selectively connecting different frequency bands to the antenna, thereby reducing the overall number of circuit elements while maintaining versatility.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The switch circuit is designed to perform multiple functions across different communication systems. A single switch circuit structure handles GSM (900 MHz), DCS (1,800 MHz), and PCS (1,900 MHz) bands by using frequency-selective switching, allowing one circuit to replace what would traditionally require multiple separate circuits.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multiple diode switch circuits are used to achieve signal switching, then transmission and reception switching is enabled, but the cost increases due to the increase in circuit elements

Engineering Contradiction:

Improvetransmission and reception switchingVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent merges the functionality of multiple separate diode switch circuits into a single integrated switch circuit. By combining the switching functions for GSM, DCS, and PCS systems into one circuit block, the total number of diodes and associated components is reduced, leading to lower manufacturing costs while maintaining the ability to switch between transmission and reception modes across all systems.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If many circuit elements are connected in the transmission system to achieve signal switching, then multi-system communication is enabled, but signal loss increases and communication characteristics are worsened

Engineering Contradiction:

Improvemulti-system communication capabilityVSAvoidsignal loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent reduces signal loss by merging multiple switching functions into a single efficient circuit path. The integrated switch circuit minimizes the number of connection points and circuit elements that signals must pass through, thereby reducing cumulative insertion loss and improving overall communication characteristics while still supporting multiple systems.

Inventive Principle:

Principle #5Merging (Combining)

4Volume of moving object

If a compact module design is pursued to reduce size, then miniaturization is achieved, but adequate signal isolation between different communication systems becomes difficult to ensure

Engineering Contradiction:

Improvemodule sizeVSAvoidsignal isolation

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent segments the frequency spectrum into distinct bands (GSM 900 MHz, DCS 1,800 MHz, PCS 1,900 MHz) and uses frequency-selective switching to route each band through dedicated paths within the compact module. This segmentation approach allows adequate signal isolation to be maintained even in a small form factor by ensuring that signals from different frequency bands do not interfere with each other through proper routing and filtering.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS7904031B2High-frequency module for transmitting and receiving transmission-reception signals of at least three communication systems using a single antenna

Publication Date: 2011.03.08 MURATA MFG CO LTD

AI summary

A high-frequency module includes a GaAs switch defining an FET switch for selectively connecting one of four RF input-output terminals to an antenna input-output terminal to be connected to an antenna. A GSM transmission signal input terminal is connected to the RF input-output terminal of the GaAsSW through a low-pass filter, and a DCS/PCS transmission signal input terminal is connected to the RF input-output terminal through a low-pass filter. A GSM 850 reception signal output terminal and a PCS reception signal output terminal are connected to the RF input-output terminal through a diplexer, and a GSM 900 reception signal output terminal and a PCS reception signal output terminal are connected to the RF input-output terminal through a diplexer.