RF Switch Module Using Shared Filter Impedance Matching
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Solution Overview
Problem
Existing switch modules for wireless communication face challenges in supporting multiple frequency bands and modes without degrading signal quality, particularly in carrier aggregation mode, and tend to increase in size due to the need for additional impedance matching components.
Innovation Solution
A switch module that includes multiple filter circuits and a switch circuit with a common terminal and selection terminals, allowing for impedance equalization across different frequency bands and modes, reducing propagation loss and insertion loss by adjusting impedance matching without additional components in certain configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inductor is added for impedance matching when two duplexers are used in parallel, then frequency characteristics are improved, but the electronic circuit increases in size
Solution Approach 1:
The third filter circuit is designed to serve dual purposes: it functions as a filter for a third frequency band during single-band operation, and simultaneously serves as an impedance matching element when two duplexers are used in parallel. This eliminates the need for a separate inductor component, resolving the contradiction between maintaining frequency characteristics and reducing circuit size.
Solution Approach 2:
The invention changes the operational parameters of the third filter circuit based on the operating mode. In parallel dual-band mode, the third filter circuit is configured to provide impedance matching characteristics, while in single-band mode, it provides filtering characteristics for the third frequency band. This parameter change allows one component to fulfill multiple functions.
2Loss of energy
If multiple filter circuits are connected to the common terminal in single band mode, then impedance equalization is achieved and propagation loss is reduced, but the switch circuit complexity increases
Solution Approach 1:
The switch circuit is designed to dynamically reconfigure the connection topology based on the operating mode. In single-band mode, multiple filter circuits are connected to the common terminal to achieve impedance equalization and reduce propagation loss. In dual-band parallel mode, the switch circuit reconfigures to connect only the necessary filter circuits. This dynamic reconfiguration allows the system to optimize performance for each mode without permanent complexity.
Solution Approach 2:
The switch circuit is segmented into multiple independent switching elements that can control the connection state of each filter circuit independently. This segmentation allows flexible configuration where only the necessary filter circuits are connected in each operating mode, reducing the effective complexity while maintaining the capability for impedance equalization when needed.
Data Source
AI summary
A switch module switches among a first state where first and second frequency bands are used in parallel, a second state where only the first frequency band is used, and a third state where none of the first and second frequency bands is used, and includes first, second, and third filters and an antenna switch. In the first state, a common terminal and the first and second filters are connected and the common terminal and the third filter are not connected. In the second state, the common terminal and the first and third filters are connected, and the common terminal and the second filter are not connected.