Coplanar CPW Filter with Recessed Ground for Miniaturization
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Solution Overview
Problem
Existing parallel coupled CPW line filters face challenges in achieving miniaturization and cost-effective fabrication due to complex processes and increased size, particularly when trying to enhance coupling between coupled lines and ground for wider bandwidth.
Innovation Solution
A parallel coupled CPW line filter design where coupled lines and ground are formed on the same plane, with recessed ground parts and zigzag bent lines, allowing for easier alignment and reduced size, while maintaining strong coupling through adjusted impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gaps between coupled lines are shortened or width of coupled lines is reduced to increase bandwidth, then coupling between coupled lines and ground is strengthened, but fabrication process becomes complicated and cost increases
Solution Approach 1:
The invention transitions from a traditional three-layer structure (coupled lines on one side, ground on the other side separated by insulating body) to a coplanar structure where both coupled lines and ground are formed on the same plane. This dimensional reconfiguration allows the ground to be positioned adjacent to the coupled lines without requiring precise vertical alignment through insulating layers, thereby simplifying fabrication while maintaining strong coupling for wide bandwidth.
2Reliability
If number of coupled lines is increased to increase bandwidth, then coupling is improved, but filter size becomes bulky
Solution Approach 1:
By placing the ground on the same plane as the coupled lines rather than on a separate layer, the invention enables more efficient spatial utilization. The coplanar configuration allows the electromagnetic fields to be concentrated in a smaller area while maintaining the necessary coupling, thus achieving wide bandwidth without increasing the overall filter footprint.
3Reliability
If aperture is formed on ground to improve coupling, then bandwidth increases, but alignment precision between coupled lines and aperture becomes critical
Solution Approach 1:
The invention eliminates the aperture structure from the ground by directly forming the ground pattern on the same plane as the coupled lines. This extraction of the aperture requirement removes the critical alignment constraint, as the coplanar ground can be precisely positioned relative to the coupled lines through standard photolithography processes without requiring complex multi-layer alignment.
4Reliability
If insulating body thickness is increased to adjust distance between coupled lines and ground, then coupling is improved, but miniaturization becomes difficult
Solution Approach 1:
The invention achieves strong coupling without increasing the thickness of the insulating body by reconfiguring the ground and coupled lines to lie on the same plane. This coplanar arrangement allows the electromagnetic interaction to occur laterally rather than vertically, maintaining effective coupling while enabling miniaturization in the vertical dimension.
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
Facilitates easier and cost-effective fabrication, achieves miniaturization, and enhances coupling between coupled lines and ground, supporting Ultra Wide Band (UWB) communications with improved bandwidth and reduced size.
Implementation Method 1
When the electric current flows along the coupled lines 20 in opposite directions as shown in FIG. 2B, electromagnetic field is formed between the coupled lines 20
Implementation Method 2
the impedance Zoe increases as the distance between the coupled lines 20 and the ground 10 increases, and accordingly, the coupling C therebetween is strengthened
Data Source
AI summary
A parallel coupled CPW line filter is provided, including a first and a second coupled lines arranged on one side of an insulating body and connected in parallel with each other, and a ground arranged on the same plane as the first and the second coupled lines, comprising a pair of ground parts spaced apart from the first and the second coupled lines, respectively, the ground parts each comprising recesses sunken from areas close to the first and the second coupled lines.