Acoustic Wave Filter Resonators for Lower Third Harmonics
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Solution Overview
Problem
Band pass filters with multiple acoustic wave resonators suffer from increased harmonic wave levels due to reduced linearity, leading to deteriorated filter characteristics.
Innovation Solution
The use of a first resonator with an epitaxial film and a second resonator with a non-epitaxial film, connected in parallel or series, to improve linearity and lower harmonic wave levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polycrystalline thin film with twin crystal structure is used for the electrode, then stress migration resistance is improved and electric power handling capability is enhanced, but linearity deteriorates and harmonic wave level rises
Solution Approach 1:
The electrode is divided into two distinct layers: an underlying electrode layer and a main electrode layer. The underlying layer (made of Al, Cu, or Ag) provides stress migration resistance and electric power handling capability, while the main layer (made of Ti, W, Mo, or Ni) provides high linearity and low harmonic wave generation. This segmentation allows each layer to optimize its function independently, resolving the contradiction between durability and linearity.
Solution Approach 2:
The electrode uses a composite structure combining two different metal materials with complementary properties. The underlying layer material is selected for its stress resistance and power handling, while the main layer material is selected for its linearity and low harmonic generation. This composite approach allows the electrode to simultaneously achieve both stress migration resistance and low harmonic wave level.
2Object-generated harmful factors
If an epitaxial film is used for the IDT electrode, then linearity is improved and harmonic wave level is lowered, but stress migration resistance may be reduced
Solution Approach 1:
The electrode is divided into two distinct layers: an underlying electrode layer and a main electrode layer. The underlying layer (made of Al, Cu, or Ag) provides stress migration resistance and electric power handling capability, while the main layer (made of Ti, W, Mo, or Ni) provides high linearity and low harmonic wave generation. This segmentation allows each layer to optimize its function independently, resolving the contradiction between durability and linearity.
Solution Approach 2:
The electrode uses a composite structure combining two different metal materials with complementary properties. The underlying layer material is selected for its stress resistance and power handling, while the main layer material is selected for its linearity and low harmonic generation. This composite approach allows the electrode to simultaneously achieve both stress migration resistance and low harmonic wave level.
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
Significantly reduces third harmonic wave signals by up to 5-10 dBm in specific frequency ranges, enhancing filter performance and maintaining signal strength.
Implementation Method 1
an acoustic wave device according to a preferred embodiment of the present invention includes a piezoelectric layer, an IDT electrode laminated on the piezoelectric layer
Data Source
AI summary
An acoustic wave device includes an IDT electrode laminated on a piezoelectric substrate and defining a first resonator, and an IDT electrode laminated on the piezoelectric substrate and defining a second resonator. The first and second resonators are connected in parallel or in series. The IDT electrode of the first resonator includes an electrode layer including an epitaxial film and the IDT electrode of the second resonator includes an electrode layer including a non-epitaxial film.