3D Stacked Filter Circuit for Millimeter-Wave Miniaturization
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Solution Overview
Problem
Designing miniaturized filters for millimeter-wave applications that offer good filtering performance and can be easily implemented on package substrates is challenging, particularly in 5G wireless communications and 77 GHz automotive radar technologies, where tradeoffs between physical size, insertion loss, and co-design with active devices need to be balanced.
Innovation Solution
A filter circuit comprising input and output nodes with first and second filtering elements, where the filtering elements are implemented using traces routed on a substrate, functioning as notch or band-pass filters to separate signals by frequency, allowing wanted signals to pass while blocking unwanted ones, with adjustable trace lengths to optimize filtering performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional filter designs are used, then filtering performance is achieved, but physical size becomes large and insertion loss increases
Solution Approach 1:
The patent transitions from traditional planar filter layouts to a three-dimensional stacked configuration where filtering elements are arranged in multiple layers vertically. This dimensional change allows the filter to achieve the required filtering performance with a significantly reduced footprint area, as the filtering function is distributed across multiple vertical layers rather than requiring a large planar area.
Solution Approach 2:
The patent implements a nested structure where multiple filtering elements and transmission lines are integrated within a compact stacked architecture. Each layer contains filtering elements that are electrically connected to elements on adjacent layers, creating a nested arrangement that maximizes the filtering function within a minimal physical volume.
2Reliability
If traditional filter designs are used, then filtering performance is achieved, but insertion loss increases
Solution Approach 1:
By stacking filtering elements in three dimensions, the patent reduces the signal path length within each individual layer, thereby minimizing resistive losses and improving insertion loss performance while maintaining the required filtering characteristics.
Solution Approach 2:
The filter is segmented into multiple independent filtering elements arranged in different layers. This segmentation allows each element to be optimized for minimal loss at its operating frequency, and the overall filtering performance is achieved through the combined effect of these low-loss segmented elements.
3Volume of moving object
If filter size is reduced, then miniaturization is achieved, but implementation complexity on package substrate increases
Solution Approach 1:
The patent resolves implementation complexity by organizing the stacked filter elements in a systematic vertical arrangement where corresponding elements on different layers are aligned. This regular stacking pattern simplifies the routing and interconnection design compared to attempting to pack miniaturized elements in a planar configuration, making the fabrication process more manageable.
Data Source
AI summary
A filter circuit includes an input node, an output node, a first filtering element and a second filtering element. The first filtering element has a first terminal coupled to the input node and a second terminal, and is configured to provide a first signal conducting path toward the second terminal for conducting a first signal received at the input node to the second terminal. The second filtering element has a first terminal coupled to the input node and a second terminal, and is configured to provide a second signal conducting path toward the output node for conducting a second signal received at the input node to the output node. The second terminal of the first filtering element and the second terminal of the second filtering element are open-circuit terminals.