Multilayer Front-End Filter Layout for Stable Frequency Response
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Solution Overview
Problem
Existing filters in wireless communication terminals face challenges in maintaining consistent transmission characteristics due to shifts in dielectric layers, leading to variations in passband and attenuation pole frequencies.
Innovation Solution
A filter design incorporating multiple parallel resonant circuits and strategically positioned via wirings within a multilayered structure, where capacitors and striplines are shunt-connected to specific nodes, and via wirings connect these components to input, output, and ground terminals, stabilizing the frequency response by maintaining magnetic field coupling and reducing the impact of dielectric layer shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multilayered filter structure with via wirings is used, then the filter can achieve frequency selection and attenuation functions, but the transmission characteristics vary when dielectric layers shift
Solution Approach 1:
The patent applies preliminary action by pre-positioning via wirings to connect strip lines across dielectric layers before the layers are assembled. The via wirings are formed in advance in the dielectric layers to establish electrical connections, so that when the dielectric layers are stacked, the connections are already in place. This preliminary preparation ensures that even if layers shift during assembly, the electrical connections remain stable and consistent, maintaining reliable filter performance.
Solution Approach 2:
The patent uses via wirings as intermediary elements that mediate the electrical connection between strip lines on different dielectric layers. These via wirings act as intermediaries that transfer electromagnetic signals through the dielectric layers, ensuring stable connections despite potential layer shifts. The intermediary via wirings isolate the impact of layer position variations from the overall filter performance.
2Ease of manufacture
If via wirings are used to connect strip lines across dielectric layers, then electrical connections are established, but frequency variation occurs when via wirings shift
Solution Approach 1:
The via wirings are formed in advance within the dielectric layers during the manufacturing process, before the layers are stacked. This preliminary formation of via wirings allows for precise positioning and alignment to be built into the structure, reducing sensitivity to assembly variations. The preliminary action of creating via holes and filling them with conductive material ensures precise positioning without requiring high-precision alignment during final assembly.
Solution Approach 2:
The patent applies beforehand cushioning by designing the via wiring structure with sufficient length and positioning tolerance to accommodate potential shifts during assembly. The via wirings are made long enough to maintain electrical connection even if dielectric layers shift slightly from their intended positions. This prior cushioning against position variations ensures that manufacturing precision requirements are relaxed while still achieving reliable connections.
3Measurement precision
If multiple parallel resonant circuits are used, then frequency selectivity is improved, but the structure becomes more complex
Solution Approach 1:
The patent merges multiple parallel resonant circuits into a single integrated filter structure where multiple strip lines and capacitors are combined on stacked dielectric layers. Instead of separate discrete resonant circuits, the design integrates multiple resonance paths that share common dielectric layers and via wiring infrastructure. This merging reduces overall structural complexity while maintaining the frequency selectivity benefits of multiple resonant circuits.
Solution Approach 2:
The patent resolves complexity by transitioning from a planar two-dimensional layout to a three-dimensional stacked configuration. Multiple parallel resonant circuits are arranged in different layers along the vertical dimension, allowing frequency-selective functionality to be achieved without increasing the footprint or planar complexity. This dimensional change enables compact integration of multiple resonant circuits while maintaining manufacturability.
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 solution effectively minimizes frequency variation and maintains consistent filter characteristics even when via wirings shift, reducing the change in passband width and attenuation at higher frequencies, thereby enhancing the reliability of the filter's performance.
Implementation Method 1
a first parallel resonant circuit including a first capacitor and a first line... a second parallel resonant circuit including a second capacitor and a second line
Implementation Method 2
an inductor and a capacitor as disclosed in Japanese Patent Application Publication Nos. 2012-209767 and 2014-53689
Data Source
AI summary
A filter includes: first and second parallel resonant circuits including a first capacitor, a first line, a second capacitor, and a second line that are shunt-connected to a series pathway connecting the input and output terminals; and first to sixth vias penetrating through a second dielectric layer on which the first and second lines are disposed, the first via connecting the first line to the series pathway, the second via connecting the first line to the ground terminal, the third via connecting the first line at a position between the first and second vias to the first connection line at a first position, the fourth via connecting the second line to the series pathway, the fifth via connecting the second line to the ground terminal, the sixth via connecting the second line at a position between the fourth and fifth vias to the first connection line at a second position.