3D RF Filter With Separate Capacitive Inductive Substrates
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Solution Overview
Problem
Current low pass RF filters, particularly lumped LC and planar 2D printed circuit board types, suffer from high insertion loss and slow roll-off rejection, and are costly due to manual assembly and discrete component requirements.
Innovation Solution
A three-dimensional RF filter design featuring separate capacitive and inductive substrates coupled together, utilizing low impedance capacitive and high impedance inductive RF signal transmission lines to create transmission zeros, reducing insertion loss and improving roll-off performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If lumped LC or planar 2D printed circuit board low pass filters are used, then the filter structure is simple and easy to manufacture, but the insertion loss is high and the roll-off rejection is slow
Solution Approach 1:
The patent transitions from planar 2D printed circuit board filters to a three-dimensional structure where capacitive and inductive substrates are stacked and coupled together. This 3D configuration reduces the current path length and parasitic effects, thereby reducing insertion loss while maintaining manufacturing simplicity through standardized substrate coupling techniques.
Solution Approach 2:
The filter is segmented into separate capacitive and inductive substrates that are coupled together. This segmentation allows independent optimization of capacitive and inductive elements, enabling lower insertion loss through optimized current paths while keeping each substrate relatively simple to manufacture.
2Ease of manufacture
If lumped LC or planar 2D printed circuit board low pass filters are used, then the filter structure is simple and easy to manufacture, but the roll-off rejection is slow
Solution Approach 1:
The three-dimensional stacking of capacitive and inductive substrates creates shorter coupling paths and more effective electromagnetic field confinement, enabling faster roll-off rejection. The vertical arrangement allows for more compact filter sections that achieve steeper attenuation characteristics without complicating the manufacturing process.
Solution Approach 2:
The patent implements different impedance characteristics in different regions of the filter structure. By creating high impedance inductive paths and low impedance capacitive paths in specific locations, the filter achieves faster roll-off rejection through localized impedance transformations that do not require complex overall restructuring.
3Loss of energy
If separate capacitive and inductive substrates are coupled together in a 3D configuration, then insertion loss is reduced and roll-off rejection is improved, but the device complexity increases
Solution Approach 1:
By dividing the filter into separate capacitive and inductive substrates, each with relatively simple individual structures, the patent reduces the complexity of each component while achieving superior overall performance through their coupling. This segmentation allows standard manufacturing techniques to be applied to each substrate independently.
Solution Approach 2:
The coupled substrate structure serves multiple functions simultaneously: it provides the filtering action, reduces insertion loss through optimized current paths, and achieves fast roll-off through the 3D configuration. This multi-functionality is achieved without proportionally increasing complexity, as the same basic substrate coupling structure accomplishes all these goals.
4Loss of energy
If separate capacitive and inductive substrates are coupled together in a 3D configuration, then insertion loss is reduced and roll-off rejection is improved, but the manufacturing and assembly process becomes more difficult
Solution Approach 1:
The capacitive and inductive substrates are prepared separately with pre-defined coupling interfaces before being assembled together. This preliminary preparation of standardized interfaces simplifies the final assembly process, allowing the substrates to be coupled efficiently without complex alignment procedures, thereby reducing assembly difficulty while maintaining the 3D configuration benefits.
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 3D filter design achieves low insertion loss and fast roll-off rejection while being more cost-effective and easier to manufacture and assemble compared to traditional filters.
Implementation Method 1
A three-dimensional RF filter design featuring separate capacitive and inductive substrates coupled together, utilizing low impedance capacitive and high impedance inductive RF signal transmission lines to create transmission zeros
Data Source
AI summary
An RF filter comprises a first substrate which in one embodiment is a plate including one or more exterior surfaces with a pattern of conductive material defining a plurality of capacitors. A second substrate which in one embodiment is a block includes one or more exterior surfaces with a pattern of conductive material defining a plurality of inductors. The block is seated on the plate in a relationship with the block normal to the plate and the capacitors coupled to the inductors respectively. In one embodiment, the capacitors comprise low impedance open ended capacitive RF signal transmission lines and the inductors comprise high impedance inductive RF signal transmission lines coupled to the low impedance capacitive RF signal transmission lines respectively to define transmission zeros.