RF Extractor Inductor Coupling for Harmonic Isolation Loss
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Solution Overview
Problem
In extractors combining band pass filters and band elimination filters, isolation is reduced in frequency bands higher than the stop band due to harmonic waves, leading to degraded insertion loss.
Innovation Solution
The extractor design includes a band elimination filter with series arm resonators and inductors, and a band pass filter connected via an external inductor, which provides a bypass path for radio-frequency signals, reducing insertion loss by inductive coupling and optimizing frequency transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a band pass filter and band elimination filter are combined in an extractor, then multi-frequency band support is achieved, but isolation between filters is reduced in frequency bands higher than the stop band due to harmonic waves
Solution Approach 1:
A first inductor is introduced as an intermediary element connected between the common terminal and the external connection terminal. This inductor is inductively coupled to the second inductor in the band elimination filter, creating a bypass path that mediates the interaction between the band pass filter and band elimination filter, thereby improving isolation in frequency bands higher than the stop band
Solution Approach 2:
The extractor is segmented into distinct functional paths: a main path through the band elimination filter for stop band frequencies, and a bypass path through the first and second inductors for frequency bands higher than the stop band. This segmentation allows different frequency components to be handled by different paths, reducing harmonic interference
2Reliability
If a bypass path with inductors is added to reduce insertion loss, then signal transmission quality is improved, but device complexity increases
Solution Approach 1:
The first inductor serves multiple functions: it acts as part of the bypass path for high frequency bands, provides inductive coupling to the second inductor, and helps establish the resonant characteristics for the bypass path. The second inductor similarly serves both as part of the band elimination filter and as the coupling element for the bypass path
Solution Approach 2:
The bypass path components (first and second inductors) are merged with the existing band elimination filter structure. The second inductor is integrated into the series arm of the band elimination filter, and both inductors together form the bypass path. This merging avoids adding completely separate components and reduces overall device complexity
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 reduces insertion loss in frequency bands higher than the stop band, maintaining high-quality signal transmission and minimizing the need for additional circuit elements, while reducing the extractor's size.
Implementation Method 1
The first inductor is inductively coupled to the second inductor
Data Source
AI summary
An extractor includes an external connection terminal, a common terminal, input-output terminals, a band elimination filter that is connected to the common terminal and the first input-output terminal input-output terminal and that uses a first frequency band as a stop band, a band pass filter connected to the common terminal and the second input-output terminal and that uses a second frequency band overlapped with at least a portion of the first frequency band as a pass band, and an inductor connected on a path connecting the common terminal to the external connection terminal. The band elimination filter includes series arm resonators located on a series arm connecting the common terminal to the input-output terminal and an inductor that is located on the series arm between the series arm resonator and the first input-output terminal. The inductor is inductively coupled to the inductor.