Multi-band filter phase shift attenuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multiband filters face challenges in achieving both passband formation and sufficient attenuation in suppression bands without increasing inductance and capacitance values, leading to consistency issues and increased loss due to the number of filter stages.
Innovation Solution
A multiband filter design featuring a printed circuit board with strategically arranged filters, inductors, and capacitors, where the first filter has lower passband frequencies than the second, and signal line conductor patterns form transmission lines with differing lengths to create phase shifts, enhancing suppression in the suppression band without increasing inductance or capacitance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the inductance value of inductor and capacitance value of capacitor are increased to secure attenuation in suppression band, then the attenuation in suppression band is improved, but the consistency among passbands collapses and passband formation becomes difficult
Solution Approach 1:
The patent divides the attenuation function into two parts: individual filter attenuation and transmission line phase shift attenuation. The transmission lines connecting filters are segmented to have different lengths, creating phase shifts that contribute to suppression band attenuation without affecting passband consistency.
Solution Approach 2:
The transmission lines act as intermediaries between filters. By adjusting transmission line lengths, the patent introduces phase shifts that enhance attenuation in suppression bands without requiring increased inductance or capacitance values, thus maintaining passband consistency.
2Area of stationary object
If two filters are stacked to downsize the multiband filter, then the size is reduced, but the attenuation in suppression band outside passbands becomes insufficient
Solution Approach 1:
The patent introduces a new dimension of control by using transmission line phase shifts. Instead of relying solely on filter stack depth for attenuation, the solution uses the phase dimension created by different transmission line lengths to enhance suppression band attenuation while maintaining compact size.
3Loss of energy
If inductor and capacitor are inserted into input/output unit of each filter to improve suppression band attenuation, then the attenuation is improved, but the device complexity increases
Solution Approach 1:
The transmission lines serve multiple functions: they connect filters in parallel configuration and simultaneously provide phase shift-based attenuation enhancement. This multi-functionality avoids the need for additional inductors and capacitors, reducing device complexity while improving suppression band attenuation.
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
This design allows for the formation of passbands and attainment of desired attenuation in suppression bands without increasing attenuation outside the passbands, preventing consistency collapse and loss, while enabling easier design and downsizing of the filter.
Implementation Method 1
the difference in length between the first transmission line and the second transmission line result in a phase shift difference of the signals flowing through each the transmission lines that increases the amount of suppression in a suppression band
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 3
AI summary
The multiband filter includes a printed circuit board (10), a first filter (20), a second filter (30) having an outer dimension different from that of the first filter (20) and passband frequencies higher than those of the first filter, an input terminal (61), an output terminal (62), a first inductor (50), a first capacitor (40), which are connected except the first capacitor by signal line conductor patterns (13) to form a first transmission line, which connect the second filter (30), the input terminal (61), the output terminal (62), and the first capacitor (40) to form a second transmission line, a part thereof in the first transmission line being arranged in an area on the printed circuit board (10), formed by the difference between the outer dimensions of the first and the second filters (20) and (30), to achieve desirable passbands and enough attenuation in a suppression band outside the passbands.