Multilayer DMS Filter Wiring to Cut Loss and Frequency Drift
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Solution Overview
Problem
Existing RF filters in mobile communication devices face challenges in minimizing electrical and acoustic losses, temperature-induced frequency drift, impedance matching, bandwidth, and manufacturing costs, while also requiring miniaturization and reduced parasitic capacitances.
Innovation Solution
An 11-IDT DMS filter with a multilayer electrode structure comprising metal and dielectric materials, arranged between acoustic reflectors, which reduces electrical losses and parasitic capacitances, and includes insulating patches to minimize ohmic losses and temperature-induced frequency drift, enabling improved signal conduction and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the number of IDTs is increased to improve filter performance, then electrical losses are reduced, but the device area increases
Solution Approach 1:
The patent transitions from a planar arrangement of IDTs to a three-dimensional stacked configuration where multiple IDT pairs are arranged vertically between acoustic reflectors. This dimensional change allows increasing the number of IDTs (from 9 to 11) without proportionally increasing the device footprint, thereby reducing electrical losses while maintaining compact area.
Solution Approach 2:
The patent employs a nested structure where multiple IDT pairs are stacked between acoustic reflectors, with each IDT pair nested within the vertical space defined by the reflectors. This nesting approach maximizes the use of available space, allowing more IDTs to be incorporated without linearly increasing the device area.
2Productivity
If a multilayer electrode structure with dielectric material is used to reduce parasitic capacitances, then filter bandwidth is improved, but device complexity increases
Solution Approach 1:
The patent introduces a multilayer electrode structure combining metal layers with dielectric material layers. This composite structure effectively reduces parasitic capacitances between adjacent IDT fingers, thereby improving filter bandwidth and selectivity. The dielectric material acts as an insulating barrier that minimizes unwanted capacitive coupling.
Solution Approach 2:
The electrode structure is segmented into multiple thin layers (metal and dielectric) rather than using a single thick layer. This segmentation reduces the overall capacitance by creating multiple smaller capacitive interfaces with lower individual capacitance values, while the layered structure can be systematically manufactured.
3Area of stationary object
If the filter structure is miniaturized to meet size requirements, then device area is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent achieves miniaturization by stacking IDT pairs vertically between acoustic reflectors, utilizing the third dimension (height) to accommodate more functional elements. This vertical stacking reduces the horizontal footprint while maintaining the necessary number of IDTs for filter performance, thereby minimizing device area without excessively increasing manufacturing difficulty.
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 11-IDT DMS filter achieves reduced electrical and parasitic losses, increased bandwidth, and compatibility with miniaturization trends, while maintaining excellent filter performance and power durability, thus addressing the challenges of existing RF filters.
Implementation Method 1
the transducers have an electrode structure coupled to a piezoelectric material. Due to the piezoelectric effect, such an electrode structure together with a piezoelectric material converts between electromagnetic RF signals and acoustic RF signals
Implementation Method 2
DMS filters that work with surface acoustic waves (SAW=surface acoustic wave)
Data Source
AI summary
An improved DMS filter with electrode structures between a first port and a second port is provided. Wiring junctions are realized in multilayer crossing with dielectric material in between. There are insulating patches (L2) between crossing conductor layers (L1,L3). Signal wirings may be realized with multiple conductor layers (L1, L3) to reduce wiring resistance and the upper conductor layer (L3) of the signal wiring may partly overlap the insulating patches (L2). The insulating patches (L2) may extend over the acoustic path to achieve temperature compensation.