Hybrid Filter Layout Using Opposite Substrate Surfaces
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Solution Overview
Problem
The hybrid acoustic LC filter is large in size due to numerous components, leading to unnecessary coupling and deterioration of bandpass characteristics when mounting density is increased to reduce size.
Innovation Solution
The hybrid filter is designed with acoustic wave resonators, inductors, and capacitors disposed on opposite major surfaces of a substrate, separating circuit elements to reduce size and minimize coupling, thereby maintaining filter characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hybrid acoustic LC filter is formed by an acoustic wave resonator-inductor-capacitor combination, then the filter achieves a wide pass band and strict out-of-band rejection specification, but the filter includes many components and becomes relatively large in size
Solution Approach 1:
The patent applies dimensionality change by disposing circuit elements on both the first major surface and the second major surface (opposite surface) of the substrate. This three-dimensional arrangement allows the filter to achieve compact size while maintaining the necessary component separation, resolving the contradiction between small size and filter characteristic maintenance.
2Volume of moving object
If the mounting density is increased for the purpose of reducing the size, then the filter size is reduced, but unnecessary coupling between components occurs and the bandpass characteristic of the filter deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the circuit elements into two groups disposed on opposite surfaces of the substrate. This spatial segmentation reduces unnecessary coupling between components while maintaining compact overall size, thereby preserving bandpass characteristics despite high mounting density.
Solution Approach 2:
The patent utilizes the third dimension (z-axis) by disposing elements on both major surfaces of the substrate rather than concentrating all elements on a single plane. This dimensional arrangement reduces parasitic coupling while achieving compact footprint, resolving the contradiction between size reduction and characteristic maintenance.
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 results in a smaller hybrid filter with suppressed degradation of filter characteristics, enabling a multiplexer, radio-frequency module, and communication device.
Implementation Method 1
one or more acoustic wave resonator elements disposed at the substrate... the resonance band width of the one or more acoustic wave resonator elements
Data Source
AI summary
A hybrid filter includes a module substrate having a major surface and a major surface that are opposite to each other, acoustic wave resonator elements disposed at the module substrate, inductors disposed at the module substrate, and a capacitor disposed at the module substrate. The pass band of the hybrid filter is wider than the resonance band width of the acoustic wave resonator elements. One of the acoustic wave resonator elements, the inductors, and the capacitor is a first circuit element, and the first circuit element is disposed at the major surface. Another of the acoustic wave resonator elements, the inductors, and the capacitor is a second circuit element, and the second circuit element is disposed at the major surface.