Hybrid Acoustic Wave Filter Using High-Q Mount Inductors
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Solution Overview
Problem
High frequency filters with LC resonant circuits and acoustic wave resonators suffer from degraded bandpass characteristics due to small Q-factors and inductance value variations in the inductors formed using wiring pattern conductors, leading to increased insertion loss and filter characteristic deviations.
Innovation Solution
Incorporating a mount component inductor with a large Q-factor into the high frequency filter, which forms a hybrid filter with the capacitive component of the acoustic wave resonator or a capacitor, to improve the bandpass characteristic and reduce inductance value deviations, while aligning the magnetic flux direction parallel to the substrate to prevent eddy currents and electromagnetic coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an inductor is formed using a wiring pattern conductor within a substrate, then the device complexity is reduced and ease of manufacture is improved, but the Q-factor becomes small and the bandpass characteristic degrades
Solution Approach 1:
The patent introduces a mount component inductor as an intermediary element with high Q-factor characteristics to compensate for the poor bandpass characteristics caused by the wiring pattern inductor. This mount component inductor acts as a mediator that improves the overall filter performance without requiring changes to the integrated wiring pattern inductor structure
Solution Approach 2:
The patent changes the Q-factor parameter by introducing a mount component inductor with specifically designed high Q-factor characteristics (Q-factor of 20 or more at 2 GHz). This parameter change directly addresses the degradation of bandpass characteristics while maintaining the ease of manufacture benefit from the integrated wiring pattern inductor
2Device complexity
If an inductor is formed using a wiring pattern conductor within a substrate, then the device complexity is reduced, but the inductance value varies depending on accuracy of width and thickness of the pattern, causing deviation of filter characteristic
Solution Approach 1:
The mount component inductor serves as a mediator that compensates for inductance value deviations caused by wiring pattern variations. By carefully designing the mount component inductor with stable inductance characteristics, the overall filter performance becomes less sensitive to manufacturing variations in the wiring pattern inductor
Solution Approach 2:
The patent applies beforehand cushioning by pre-designing the mount component inductor to compensate for expected inductance variations in the wiring pattern inductor. This prior compensation approach ensures that filter characteristic deviations are minimized even when wiring pattern dimensions vary during manufacturing
3Speed
If the frequency of the second attenuation pole is positioned closer to the passband, then the steepness of the attenuation slope is increased, but the stopband width is reduced
Solution Approach 1:
The patent resolves this contradiction by operating in another dimension - using a mount component inductor with specific Q-factor characteristics to enhance the attenuation slope steepness without directly moving the second attenuation pole. This dimensional approach allows independent optimization of both attenuation slope and stopband width
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 solution enhances the steepness of the attenuation slope, broadens the stopband, and reduces insertion loss within the passband, achieving improved filter characteristics with a Q-factor of 20 or more at 2 GHz and minimizing variations in the filter characteristics.
Implementation Method 1
aligning the magnetic flux direction parallel to the substrate to prevent eddy currents and electromagnetic coupling
Implementation Method 2
aligning the magnetic flux direction parallel to the substrate to prevent eddy currents and electromagnetic coupling
Implementation Method 3
an acoustic wave resonator and at least one inductor, wherein a capacitive component of the acoustic wave resonator constitutes a hybrid filter
Implementation Method 4
the acoustic wave resonator and the LC resonant circuit, each constitutes a band elimination filter (BEF)
Data Source
AI summary
A high frequency filter includes series arm resonators and parallel arm resonators as acoustic wave resonators and at least one inductor, wherein capacitive components of the acoustic wave resonators constitute an LPF and an HPF as hybrid filters with an inductor or with an inductor and a capacitor, and the at least one inductor includes inductors as mount component inductors.