Hybrid RF Filter Layout to Limit Inductor Magnetic Coupling
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Solution Overview
Problem
Existing radio-frequency modules experience a decrease in characteristics due to the magnetic field generated by the inductor, which affects the performance of the acoustic wave filter.
Innovation Solution
A radio-frequency module design where the inductor is disposed on the first major surface of the mounting substrate, adjacent to the acoustic wave filter, and positioned such that the inner part of the inductor's winding portion does not overlap with the input/output electrodes of the acoustic wave filter, thereby minimizing electromagnetic coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inductor is disposed on the first major surface of the mounting substrate adjacent to the acoustic wave filter, then the magnetic field generated by the inductor affects the characteristics of the radio-frequency module, but the inductor is needed for the hybrid filter functionality
Solution Approach 1:
The patent extracts the harmful magnetic field effect by positioning the inductor's winding portion such that its inner part does not overlap with the input/output electrodes of the acoustic wave filter. This spatial separation removes the detrimental magnetic coupling while preserving the inductor's necessary function in the hybrid filter circuit.
Solution Approach 2:
The patent applies local quality by creating a specific non-overlapping arrangement between the inductor and acoustic wave filter electrodes in the overlapping region. The inductor is disposed adjacent to the acoustic wave filter with controlled positioning, ensuring that the harmful magnetic field effect is localized and avoided in critical areas while maintaining overall system functionality.
2Reliability
If the inductor overlaps with the input/output electrodes of the acoustic wave filter, then the magnetic coupling increases, but this degrades the attenuation near the pass band of the hybrid filter
Solution Approach 1:
The patent extracts the harmful magnetic coupling by designing the inductor position such that the inner part of the winding portion does not overlap with the input/output electrodes. This removes the source of excessive magnetic coupling that would otherwise degrade the attenuation characteristics near the pass band.
Solution Approach 2:
The patent applies preliminary anti-action by pre-positioning the inductor to avoid overlapping with the electrodes before the harmful magnetic coupling can occur. The design proactively prevents the degradation of attenuation characteristics by establishing a non-overlapping configuration from the outset.
3Reliability
If the inductor is positioned to minimize electromagnetic coupling with the acoustic wave filter, then the isolation between signal terminals improves, but the layout complexity increases
Solution Approach 1:
The patent applies local quality by implementing a specific non-overlapping arrangement only in the critical region where the inductor interacts with the acoustic wave filter electrodes. This localized design approach improves isolation between signal terminals without requiring complete redesign of the entire layout, thus limiting the increase in layout complexity to a manageable scope.
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 design effectively suppresses the degradation of attenuation near the pass band of the hybrid filter, maintaining the characteristics of the radio-frequency module and improving isolation between signal terminals.
Implementation Method 1
the characteristics of the radio-frequency module can be decreased under the influence of the magnetic field generated by the inductor
Data Source
AI summary
In a radio-frequency module, a hybrid filter includes an acoustic wave filter including at least one acoustic wave resonator, an inductor having a winding portion, and a capacitor. A plurality of outer electrodes of the acoustic wave filter includes a first input and output electrode connected to a first signal terminal, a second input and output electrode connected to a second signal terminal, and a ground electrode connected to a ground terminal. The inductor is disposed on a first major surface of a mounting substrate and is adjacent to the acoustic wave filter in plan view in a thickness direction of the mounting substrate. When viewed in a direction of a winding axis of the winding portion of the inductor, an inner part of the winding portion in the inductor does not overlap any of the first input and output electrode, the second input and output electrode, and ground electrode.