Diplexer Attenuation Pole Layout for Low-Loss High-Band Filtering
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Solution Overview
Problem
Existing diplexers face challenges in improving attenuation characteristics in higher frequency bands without increasing loss, particularly in communication systems like Wi-Fi and 5G, where adding elements to the high frequency side filter can lead to increased loss.
Innovation Solution
A diplexer with a multilayer structure featuring a low pass filter on the low band side with a smaller inductance inductor and a high pass filter on the high band side, where the frequency of the attenuation pole defined by the inductor and capacitor is set higher than the high band pass band, allowing for improved attenuation without adding new elements to the high band side, thereby reducing loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an inductor is added to the high frequency side filter to improve attenuation characteristics in higher frequency bands, then attenuation characteristics are improved, but loss of the high frequency side filter increases
Solution Approach 1:
The invention extracts the attenuation pole generation function from the high frequency side filter and relocates it to the low frequency side filter. By removing the need for additional inductors in the high frequency side filter and implementing the attenuation mechanism in the low frequency side filter instead, the solution reduces filter loss while maintaining improved attenuation characteristics in higher frequency bands.
2Object-affected harmful factors
If elements are added to improve attenuation characteristics, then attenuation performance is enhanced, but device complexity increases
Solution Approach 1:
The invention makes the low frequency side filter serve multiple functions: it maintains its original low frequency signal passing function while simultaneously generating an attenuation pole for high frequency signal attenuation. This multi-functionality allows the single low frequency side filter to perform both frequency selection and high frequency attenuation, reducing the need for additional elements and simplifying the overall device structure.
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
Significantly enhances attenuation characteristics in higher frequency bands while maintaining low loss, effectively addressing the need for improved frequency attenuation without increasing overall filter loss.
Implementation Method 1
A frequency of an attenuation pole defined by the first inductor and the first capacitor is higher than a frequency of the second frequency band
Data Source
AI summary
A diplexer includes a common terminal, first and second terminals, and first and second filters which are electrically connected to the common terminal. The first filter passes a high frequency signal in a first frequency band. The second filter passes a high frequency signal in a second frequency band higher than the first frequency band. Each filter includes an inductor and a capacitor in a dielectric substrate. The first filter includes a first inductor with one end electrically connected to the common terminal, and a first capacitor electrically connected between another end of the first inductor and a ground. An inductance of the first inductor is smaller than an inductance of another inductor included in the first filter. A frequency of an attenuation pole defined by the first inductor and the first capacitor is higher than a frequency of the second frequency band.