24 GHz Stepped-Impedance Band-Pass Filter for Harmonic Suppression
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Solution Overview
Problem
Conventional bandpass filters are affected by the frequency multiplication effect, requiring high signal attenuation to prevent unwanted frequency bands from being amplified, which complicates their design and layout.
Innovation Solution
A 24 GHz bandpass filter with a stepped impedance resonator design that shifts multiplied frequencies away from the passband using a stepped impedance characteristic, combined with short-circuit stubs and open-circuit stubs to enhance bandwidth and suppress noise, and can be fabricated on a flexible substrate like Liquid Crystal Polymer (LCP) for flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional filters are used, then the design is simple, but the passband is affected by frequency multiplication effect requiring high signal attenuation
Solution Approach 1:
The patent changes the impedance parameters along the resonator path, creating stepped impedance sections with different characteristic impedances. This parameter variation shifts the frequency multiplication effect away from the passband, achieving high signal attenuation at unwanted frequencies without requiring complex additional filtering stages
Solution Approach 2:
The resonator is divided into multiple sections with different impedance levels (high impedance sections and low impedance sections). This segmentation allows different parts of the resonator to handle different frequency components, with the stepped impedance structure naturally suppressing frequency multiplied signals while maintaining passband performance
2Object-generated harmful factors
If high signal attenuation is required to prevent frequency multiplication, then unwanted frequencies are suppressed, but the filter design becomes more complex
Solution Approach 1:
By varying the impedance parameters along the resonator length and introducing stepped impedance transformations, the patent shifts the frequency multiplication effect to higher frequencies outside the passband. This achieves harmful factor suppression through parameter optimization rather than structural complexity
Solution Approach 2:
The patent converts the frequency multiplication effect from a harmful phenomenon into a beneficial feature by designing the stepped impedance resonator such that frequency multiplied signals are naturally shifted to desired frequency positions or suppressed at stopband frequencies, turning potential interference into useful signal separation
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 filter effectively prevents signal amplification of unwanted frequencies, improves bandwidth, reduces space requirements, and suppresses noise, while allowing for compact and flexible integration in electronic devices.
Implementation Method 1
The 24 GHz bandpass filter adopts a stepped impedance resonator, and thus the multiplied frequencies of the passband can be shifted to higher frequencies by using the stepped impedance characteristic
Implementation Method 2
a filter with high signal attenuation is required... The filter effectively prevents signal amplification of unwanted frequencies
Data Source
AI summary
A 24 GHz band-pass filter includes a step impedance resonator, a first U-shape feeding portion, a second U-shape feeding portion, short-circuit stubs and open-circuit stubs. The step impedance resonator includes a first main portion, a second main portion, and a connection portion for connecting the main portions to each other. The first main portion and the second main portion are electrically connected to a first signal input/output port and a second signal input/output port. The first U-shape feeding portion is electrically connected between the first main portion and the first signal input/output port. The second U-shape feeding portion is electrically connected between the second main portion and the second signal input/output port. The short-circuit stubs are electrically connected to coupling segments of the step impedance resonator. The open-circuit stubs are electrically connected to the first U-shape feeding portion and the second U-shape feeding portion.