RF Module Filter Layout for Harmonic Interference Suppression
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Solution Overview
Problem
In radio frequency modules, the filter characteristic of high-frequency band pass filters is degraded due to harmonic wave components from low-frequency signals passing through low-pass filters, leading to performance issues in multimode or multiband communication devices.
Innovation Solution
Incorporating an attenuation filter, such as a low pass filter or notch filter with reactive elements like inductors and capacitors, adjacent to band pass filters on a mounting board, which shifts the pass band to the low-frequency side to block harmonic waves, thereby preventing their interference with high-frequency filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low pass filter is connected between the common terminal and antenna terminal without reactive elements adjacent to band pass filters, then the structure is simple and easy to manufacture, but the filter characteristic of the second band pass filter is degraded due to harmonic wave components overlapping its attenuation region
Solution Approach 1:
The patent introduces reactive elements (inductors or capacitors) as intermediary components positioned between the low pass filter and the second band pass filter. These reactive elements act as mediators that suppress harmonic wave components in the attenuation region of the second band pass filter, preventing degradation of its filter characteristic while maintaining a relatively simple overall structure.
Solution Approach 2:
The patent applies local quality by adding reactive elements only in specific locations where harmonic wave suppression is needed - namely, between the low pass filter and the second band pass filter in the attenuation region. This localized approach improves filter characteristic reliability only where necessary, without unnecessarily complicating the entire filter structure.
2Adaptability or versatility
If carrier aggregation is performed using first and second band pass filters, then multiband communication capability is improved, but harmonic wave components from the first frequency band overlap with the attenuation region of the second band pass filter causing performance degradation
Solution Approach 1:
The patent converts the harmful effect of harmonic wave components into a beneficial solution by strategically placing reactive elements that target and suppress these harmonics in the attenuation region of the second band pass filter. This transforms the potential interference problem into an opportunity to enhance overall system performance through selective harmonic suppression, enabling reliable carrier aggregation across multiple frequency bands.
3Reliability
If the reactive element is positioned away from band pass filters, then the layout is easier and manufacturing is simpler, but the harmonic wave suppression effect is insufficient leading to degraded filter performance
Solution Approach 1:
The patent applies local quality by positioning reactive elements in specific strategic locations - adjacent to band pass filters in the attenuation region - where harmonic wave suppression is most needed. This localized placement ensures effective harmonic suppression and maintains filter characteristic reliability while keeping the overall layout relatively simple and manufacturable.
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
This configuration effectively suppresses the degradation of high-frequency filter characteristics by blocking harmonic waves from low-frequency signals, enhancing the overall performance of radio frequency modules in communication devices.
Implementation Method 1
The attenuation filter is a low pass filter or a notch filter including at least one reactive element out of an inductive element and a capacitive element
Implementation Method 2
The attenuation filter is a low pass filter or a notch filter including at least one reactive element out of an inductive element and a capacitive element
Implementation Method 3
The attenuation filter is a low pass filter or a notch filter including at least one reactive element out of an inductive element and a capacitive element
Data Source
AI summary
A radio frequency module (1) includes a first switch (4), an attenuation filter (3), and a plurality of band pass filters (12A to 12C, 22A to 22C). The first switch (4) is a switch that is capable of simultaneously connecting a common terminal (40) to selection terminals (41, 42) out of a plurality of selection terminals (41 to 43). The plurality of band pass filters (12A to 12C, 22A to 22C) include a first band pass filter (22A) and a second band pass filter (22B). The attenuation filter (3) includes at least one reactive element out of an inductive element and a capacitive element. In the radio frequency module (1), the reactive element is adjacent to at least one band pass filter out of the plurality of band pass filters (12A to 12C, 22A to 22C).