RF Front-End Switch-Filter Layout for Stable Multi-Band Impedance
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Solution Overview
Problem
Existing radio-frequency circuits experience increased variations in filter impedances across communication bands when performing simultaneous communication, such as carrier aggregation, which affects signal transmission efficiency.
Innovation Solution
A radio-frequency circuit design that includes an antenna terminal, a first switch, a second switch, a first filter, a second filter, and an inductor. The inductor is connected in series with the first switch and the second switch between them, allowing for reduced impedance variations across filters when seen from the antenna terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple acoustic wave filters are connected directly to the antenna terminal to support simultaneous communication, then multi-band communication capability is improved, but impedance variations among filters increase
Solution Approach 1:
A series inductor is introduced as an intermediary component between the antenna terminal and the second acoustic wave filter. This inductor acts as a mediator that adjusts and balances the impedance characteristics, reducing impedance variations among multiple filters when viewed from the antenna terminal, thereby enabling stable multi-band simultaneous communication.
Solution Approach 2:
The invention changes the impedance parameter of the filter network by introducing an inductor with specific inductance value. This parameter change compensates for the inherent impedance differences among filters operating at different frequency bands, achieving consistent impedance characteristics across all bands when viewed from the antenna terminal.
2Adaptability or versatility
If filters for different communication bands are connected in parallel to the antenna terminal, then communication band coverage is improved, but signal transmission efficiency deteriorates due to impedance mismatch
Solution Approach 1:
The series inductor serves as an intermediary that improves signal transmission efficiency by reducing impedance mismatch. It mediates between the antenna terminal and filters of different communication bands, ensuring better impedance matching and reducing energy loss during simultaneous multi-band operation.
3Device complexity
If no inductor is used between switches to simplify the circuit, then device complexity is reduced, but impedance variations increase
Solution Approach 1:
By adding a single inductor component, the invention achieves significant improvement in impedance stability without substantially increasing circuit complexity. The inductor's electrical parameter (inductance) is carefully selected to compensate for impedance variations, providing a simple yet effective solution.
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
The proposed design effectively reduces variations in impedances of plural filters within communication bands, enhancing signal transmission efficiency during simultaneous communication modes.
Implementation Method 1
The radio-frequency circuit includes an inductor. The inductor is not connected in series with the first filter and is connected in series with the first switch and the second switch between the first switch and the second switch.
Data Source
AI summary
In a radio-frequency circuit, a first switch is connected to an antenna terminal. A second switch is connected to the first switch and is connected to the antenna terminal via the first switch. A first filter is connected to the first switch without having the second switch interposed therebetween and allows a radio-frequency signal of a first communication band to pass through the first filter. A second filter is connected to the first switch via the second switch and allows a radio-frequency signal of a second communication band to pass through the second filter. The second communication band is higher than the first communication band. The radio-frequency circuit further includes an inductor. The inductor is not connected in series with the first filter and is connected in series with the first switch and the second switch between the first switch and the second switch.