Miniature RF Filter Layout Using Grounded Inductive Coupling
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Solution Overview
Problem
Existing miniature filter designs for high-frequency RF applications, such as 5G millimeter wave, face challenges in realizing transmission zeros, especially on the high side of the passband, due to difficulties in realizing inductance in multilayer designs, which are often lossy and complex, such as whirl or spiral inductive structures.
Innovation Solution
An inductive coupling arrangement using a grounded coupling plate to provide inductive coupling between parallel-coupled resonators, allowing for the creation of transmission zeros on both sides of the passband, reducing complexity and loss by utilizing a simpler design compared to traditional capacitive or spiral inductive elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional capacitive coupling or spiral inductive structures are used in multilayer filters, then the filter can be miniaturized for high frequency operation, but the filter becomes very lossy and complex to manufacture
Solution Approach 1:
The patent replaces traditional capacitive coupling structures with inductive coupling using a coupling plate that provides magnetic field coupling between resonators. This substitution of the coupling mechanism reduces power loss while maintaining the miniaturized multilayer filter design, as inductive coupling through a plate structure is more efficient than capacitive coupling or spiral inductive elements in this application context
Solution Approach 2:
The patent changes the coupling parameter from capacitive to inductive by introducing a coupling plate with specific geometric parameters (size, position, orientation) between resonators. This parameter change enables transmission zero realization on the high side of the passband while reducing overall filter loss and maintaining compact dimensions
2Ease of manufacture
If traditional capacitive coupling structures are used, then the filter design is simpler to manufacture, but it is difficult to realize transmission zeros on the high side of the passband
Solution Approach 1:
The patent substitutes capacitive coupling with inductive coupling through a plate structure, enabling transmission zero realization on the high side of the passband. The coupling plate is manufactured using standard PCB or LTCC techniques, maintaining ease of manufacture while achieving the desired electromagnetic coupling characteristics for transmission zero control
Solution Approach 2:
The patent changes the coupling type from capacitive to inductive by introducing a coupling plate with controllable geometric parameters. This parameter change provides the versatility to realize transmission zeros on both sides of the passband while maintaining manufacturability through standard fabrication processes
3Adaptability or versatility
If whirl or spiral inductive structures are used to realize inductance, then transmission zeros can be realized, but the structures become very complicated and lossy
Solution Approach 1:
The patent replaces complex spiral or whirl inductive structures with a simple planar coupling plate that provides inductive coupling through its geometric configuration. This substitution dramatically reduces structural complexity while maintaining the ability to realize transmission zeros, as the coupling plate can be fabricated using standard planar technology without requiring spiral or three-dimensional winding structures
Solution Approach 2:
The patent uses the third dimension (vertical spacing between resonator layers) to create inductive coupling through the coupling plate, rather than using complex planar spiral structures. This dimensional approach allows inductance realization with simple planar geometry, reducing overall device complexity while achieving transmission zero control
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 solution effectively creates transmission zeros on both sides of the passband, enhancing filter performance and reducing size and loss, while maintaining a compact design suitable for high-frequency applications.
Implementation Method 1
An inductive coupling arrangement using a grounded coupling plate to provide inductive coupling between parallel-coupled resonators
Data Source
AI summary
A filter and array of filters providing inductive coupling are disclosed. According to one aspect, an RF filter includes a plurality of dielectric layers with a first ground plane on one side of the dielectric layers and a second ground plane on an opposite side of the dielectric layers. One of the first and second ground planes provides an input port and one of the first and second ground planes provides an output port. Two parallel strip line resonators, lie in a first plane parallel to, and between, the first and second ground planes, the two parallel strip line resonators, having a gap there between. An inductive coupling plate in proximity to the gap, is grounded at an edge and lies in a second plane, the second plane parallel to the first plane and lying between the first plane and one of the first and second ground planes.