Duplexer Filter Topology With Split Inductance Attenuation Poles
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Solution Overview
Problem
Conventional high-frequency filters face challenges in achieving low loss in the passband and high suppression in the opposite band, with increasing the number of stages in ladder filters leading to higher loss in the passband and difficulty in placing attenuation poles in frequency bands where suppression is most needed.
Innovation Solution
A filter configuration that includes a combination of series and parallel resonators connected in a specific manner, with inductors of different inductances connected to the parallel resonators, allowing for increased attenuation poles without increasing the number of stages, and placing these poles in desired frequency bands for effective suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of stages in the ladder filter is increased to increase the number of attenuation poles in suppression bands, then the suppression performance is improved, but the loss in the passband increases
Solution Approach 1:
The patent applies local quality by connecting inductors with different inductance values to different parallel resonators. Specifically, the first inductor has a first inductance value and the second inductor has a second inductance value that is different from the first. This allows each resonator-inductor combination to be optimized for specific frequency suppression requirements, achieving high suppression performance without requiring an increased number of filter stages that would otherwise increase passband loss.
2Adaptability or versatility
If inductors are connected to parallel resonators, then attenuation poles can be formed, but it is difficult to place attenuation poles in frequency bands where suppression is most needed
Solution Approach 1:
The patent employs parameter changes by utilizing inductors with different inductance values connected to different parallel resonators. The first inductor has a first inductance value and the second inductor has a second inductance value, allowing the attenuation poles to be positioned at different frequencies. This enables precise placement of attenuation poles in the frequency bands where suppression is most needed, such as placing poles in the Bluetooth and wireless LAN bands, thereby improving suppression effectiveness.
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 configuration enables reduced loss in the passband while achieving high suppression in the desired frequency bands, such as the Bluetooth and wireless LAN bands, improving the filter's performance in high-frequency applications.
Implementation Method 1
inductors are respectively connected to the at least two parallel resonators, and the inductors have different inductances from each other
Implementation Method 2
a plurality of series resonators connected to a signal line in series and a plurality of parallel resonators connected to the signal line in parallel
Data Source
AI summary
According to an aspect of the invention, each of a filter, a duplexer and a communication module includes a plurality of series resonators connected to a signal line in series and a plurality of parallel resonators connected to the signal line in parallel. At least two of the plurality of parallel resonators are connected to the signal line between two of the plurality of series resonators in parallel, inductors are respectively connected to the at least two parallel resonators, and the inductors have different inductances from each other.