3D Folded Low-Pass Filter for Miniaturized WLAN Applications
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Solution Overview
Problem
There is a need to reduce the size of filters used in wireless communication products, particularly in WLAN technology, to align with the miniaturization trend and enhance cost-effectiveness.
Innovation Solution
A low-pass filter design incorporating an input part, an output part, a high impedance part, and two low impedance parts, where the high impedance part is positioned between the low impedance parts and connected in a specific asymmetrical configuration to effectively filter electromagnetic signals, reducing the overall size while maintaining performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a microstrip filter is used to filter electromagnetic signals, then the filtering function is achieved, but the size of the filter becomes large
Solution Approach 1:
The patent transitions from traditional planar microstrip filter design to a three-dimensional structure by folding the transmission line into multiple layers. The filter comprises a first transmission line folded into a first loop and a second transmission line folded into a second loop, with the two loops positioned at different heights. This spatial arrangement in multiple dimensions enables compact filtering functionality while significantly reducing the planar area occupation.
Solution Approach 2:
The patent implements nesting by placing the first and second loops in an overlapping configuration where one loop is positioned above the other in the vertical dimension. The loops are arranged such that they occupy overlapping projected areas when viewed from above, allowing the filter to achieve compact size by nesting functional elements in three-dimensional space rather than spreading them out in two dimensions.
2Area of stationary object
If the filter size is reduced to meet miniaturization requirements, then the product size is reduced, but the filtering performance may deteriorate
Solution Approach 1:
By utilizing the vertical dimension through folded and multi-layer transmission lines, the patent maintains sufficient electrical path length for effective filtering while reducing the horizontal footprint. The folded structure increases the effective filtering length without proportionally increasing the planar area, thereby preserving filtering performance in a compact form factor.
Solution Approach 2:
The patent optimizes the geometric parameters of the folded transmission lines, including loop dimensions, spacing between loops, and characteristic impedances, to achieve effective filtering in a compact configuration. By carefully adjusting these parameters, the filter maintains its filtering performance while occupying minimal space.
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 achieves a compact filter design with good performance, as evident from the graph showing low insertion loss and high return loss, effectively suppressing noise signals and maintaining signal integrity within the pass band.
Implementation Method 1
a resonator defined by the high impedance part (140), the first low impedance part (160), and the second low impedance part (180)
Data Source
AI summary
A low-pass filter (10) is provided. The low-pass filter includes an input part (100), an output part (120), a high impedance part (140), a first low impedance part (160), and a second low impedance part (180). The input part is electronically connected to the high impedance part for input of electromagnetic signals thereinto. The output part is electronically connected to the high impedance part for output of electromagnetic signals therefrom. The input part and the output part are asymmetrical to a resonator defined by the high impedance part, the first low impedance part and the second low impedance part. One end of the high impedance part is electronically connected to the first low impedance part, the other end of that is electronically connected to the second low impedance part. Wherein the high impedance part is disposed partly between the first low impedance part and the second low impedance part.