Tunable RF Transmit Filter Impedance Matching Network

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Solution Overview

Problem

Existing radio frequency transmit filters and impedance matching networks in communications devices often experience significant insertion loss and mismatched impedances across different frequency channels, leading to inefficient signal transmission and isolation between transmitter and receiver components.

Innovation Solution

A tunable impedance matching network (TTIMN) is introduced, which includes variable/switchable reactive elements controlled by a tuning input to dynamically match the output impedance of the power amplifier to the input impedance of the transmit filter for the active frequency channel, reducing insertion loss and enhancing isolation between transmitter and receiver.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a fixed impedance matching network is used to match the output impedance of the power amplifier to the nominal impedance value, then the impedance matching is simplified and easier to manufacture, but significant insertion loss occurs at frequencies away from the design center frequency

Engineering Contradiction:

Improveimpedance matching network design simplicityVSAvoidinsertion loss

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent applies dynamics by making the impedance matching network tunable rather than fixed. The matching network includes variable reactive elements that can be adjusted based on the operating frequency channel, allowing the system to adapt to different frequency requirements and minimize insertion loss across multiple channels while maintaining manufacturability through a reconfigurable architecture.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameters of the impedance matching network by introducing tunable reactive elements whose values can be modified according to the active frequency channel. This allows the matching network to optimize its performance for different operating conditions, reducing insertion loss by adjusting the electrical parameters to match the specific frequency being used.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the output impedance of the power amplifier and the input impedance of the transmit filter are designed to deviate differently from the nominal value, then each component can be optimized for its specific function, but the mismatch between them results in significant insertion loss

Engineering Contradiction:

Improvecomponent function optimizationVSAvoidinsertion loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent introduces an intermediary tunable impedance matching network between the power amplifier and the transmit filter. This intermediary component mediates the impedance mismatch by providing adjustable reactive elements that can be tuned to bridge the gap between the differently optimized components, thereby reducing insertion loss while allowing each component to maintain its functional optimization.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The matching network is made dynamic and tunable, allowing it to adapt to the specific impedance characteristics of the power amplifier and transmit filter combination for each frequency channel. This dynamic adjustment capability enables the system to compensate for the intentional impedance deviations of individual components.

Inventive Principle:

Principle #15Dynamics

3Reliability

If separate impedance matching networks are used for different frequency channels, then each channel can be optimized independently, but the device complexity and number of components increases

Engineering Contradiction:

Improvefrequency channel optimizationVSAvoidnumber of impedance matching networks

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies universality by designing a single impedance matching network that can serve multiple frequency channels through tuning capabilities. Rather than implementing separate matching networks for each channel, the network is designed to be reconfigurable and adaptable to different frequency requirements, reducing component count while maintaining optimization for each channel.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The matching network is made dynamically reconfigurable to handle multiple frequency channels. By incorporating tunable elements that can be adjusted based on the active channel, the system achieves independent optimization for each frequency without requiring physically separate matching networks, thereby reducing overall device complexity.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10243539B2Radio frequency transmit filter with integrated impedance matching network

Publication Date: 2019.03.26 MURATA MFG CO LTD

AI summary

A transmit filter for a communications device includes a surface acoustic wave (SAW) band-pass filter configured to pass a transmit frequency band and a tunable transmitter impedance matching network in series. The tunable transmitter impedance matching network matches an input impedance of the SAW band-pass filter to the output impedance of a power amplifier over a portion of the transmit frequency band in response to a tuning input.