Multiband Filter Topology for Steep Stop-to-Passband Transition
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Solution Overview
Problem
Existing multiband filters have a wide transition width between the stop band and passband, resulting in a flattened transmission range, which is inefficient for mobile radio applications.
Innovation Solution
A multiband filter design featuring a band-stop filter with two parallel filter branches, one containing a bandpass filter and the other a high-pass filter, integrated into a multilayer substrate with LC-elements, achieving a steep transition from the stop band to the passband and allowing for multiple passbands with high relative bandwidth and low insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wide passband is used to cover multiple mobile radio bands, then the transmission range is extended, but the transition width between stop band and passband becomes excessively large
Solution Approach 1:
The filter is divided into two separate parallel filter branches: a first bandpass filter for a first mobile radio band and a second bandpass filter for a second mobile radio band. This segmentation allows each branch to be optimized independently, achieving steep transitions for both bands while maintaining wide overall coverage
Solution Approach 2:
The filter structure provides multi-functionality by simultaneously supporting multiple mobile radio bands (first band, second band, and optionally third band) through parallel filter branches, each designed for specific frequency ranges while sharing a common substrate and mounting structure
2Adaptability or versatility
If multiple bandpass filters are used in parallel to cover different frequency ranges, then the transmission range is improved, but the device complexity increases
Solution Approach 1:
Multiple bandpass filters are merged into a single compact structure by mounting them in parallel on a common substrate, sharing input and output connections, and utilizing the substrate as a common mechanical and electrical platform, thereby reducing overall device complexity
Solution Approach 2:
The filter design transitions from a planar layout to a three-dimensional structure by stacking multiple filter branches vertically on the substrate, with input and output terminals extending in different spatial dimensions, enabling compact multi-band functionality
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 design achieves a steep transition from the stop band to the passband with high attenuation, enabling efficient transmission and reception in multiple mobile radio bands with reduced insertion loss and compact, cost-effective production.
Implementation Method 1
from the first filter branch, a transverse branch is transversely connected to ground, an impedance element and, in particular, a resonator being arranged in the transverse branch. Such a construction yields a band-stop filter which has a stop band which is formed below the first passband and which undergoes transition to a first passband with a steep flank.
Implementation Method 2
bandpass filter and high-pass filter are constructed from LC-elements that are at least partly integrated in the multilayered substrate
Data Source
AI summary
A band-stop filter is proposed which is constructed on a multilayered substrate and consists of a parallel circuit comprising a bandpass filter and a high-pass filter. The two filters are at least partly realized in the form of LC-elements integrated into the substrate. Further circuit components can be arranged as discrete components on the substrate. In the filter branch having the bandpass filter, an electroacoustic resonator is arranged in a transverse branch to ground. By means of the filter, a wide stop band is obtained, while the passband or passbands can comprise a plurality of radio bands.