Acoustic Wave Resonator Electrode Layout for Lower Insertion Loss
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Solution Overview
Problem
Acoustic wave devices used in filters, particularly those employing thickness-shear mode bulk waves, face challenges in achieving high electrostatic capacitance ratios without increasing device size, leading to larger filter devices and higher insertion loss.
Innovation Solution
The acoustic wave device incorporates a piezoelectric layer made of lithium niobate, with a specific configuration of comb-shaped electrodes and a reference potential electrode, along with a pair of reflectors, to achieve miniaturization and reduce insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrostatic capacitance of the acoustic wave resonator is increased to obtain good characteristics in the ladder filter, then the filter characteristics are improved, but the acoustic wave resonator and the ladder filter are increased in size
Solution Approach 1:
The patent introduces a novel electrode configuration where a reference potential electrode is positioned between the input and output electrodes in the acoustic wave resonator. This spatial rearrangement in the electrode dimension enables increased electrostatic capacitance without proportionally increasing the overall device volume, thereby improving filter characteristics while controlling size.
Solution Approach 2:
The patent modifies the electrical parameters of the acoustic wave resonator by implementing a specific electrode arrangement that changes the capacitance distribution. By adjusting the electrode configuration parameters (positioning reference potential electrode between input and output), the electrostatic capacitance is optimized to improve filter performance without requiring proportional size increase.
2Loss of energy
If the acoustic wave resonator is increased in size to increase the electrostatic capacitance, then the electrostatic capacitance is increased, but the ladder filter becomes larger and insertion loss increases
Solution Approach 1:
The patent utilizes dimensional optimization by reconfiguring the electrode arrangement in the acoustic wave resonator. By placing the reference potential electrode between the input and output electrodes, the design achieves higher electrostatic capacitance within a controlled volume, preventing the proportional size increase that would otherwise lead to higher insertion loss.
Solution Approach 2:
The patent optimizes electrical parameters through a modified electrode configuration. By changing the spatial parameters of the electrodes (specifically positioning the reference potential electrode between input and output), the electrostatic capacitance is enhanced without requiring a proportional increase in device size, thereby controlling insertion loss.
3Loss of energy
If a simple configuration with reference potential electrode is provided, then the device structure is simplified, but insertion loss is not sufficiently reduced
Solution Approach 1:
The patent implements a specific dimensional arrangement of electrodes where the reference potential electrode is positioned between the input and output electrodes. This spatial configuration achieves sufficient insertion loss reduction while maintaining relatively simple device structure, balancing complexity and performance.
Solution Approach 2:
The patent optimizes the electrical parameters by implementing a specific electrode arrangement pattern. By changing the configuration parameters (positioning reference potential electrode between input and output), the insertion loss is sufficiently reduced while keeping the device structure relatively simple and manageable.
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 allows for a suitable filter waveform without increasing device size and reduces insertion loss, effectively addressing the challenges of size and performance in acoustic wave filter devices.
Implementation Method 1
a piezoelectric layer made of lithium niobate... An AC voltage is applied between the electrodes to excite bulk waves in the thickness-shear mode
Implementation Method 2
An acoustic wave device using bulk waves in a thickness-shear mode has recently been proposed... to excite bulk waves in the thickness-shear mode
Data Source
AI summary
An acoustic wave device includes a piezoelectric layer, first and second comb-shaped electrodes respectively including first and second electrode fingers, and a reference potential electrode including third electrode fingers. An order in which the first, second, and third electrode fingers are arranged is the first electrode finger, the third electrode finger, the second electrode finger, and the third electrode finger and defines one period. A pair of reflectors sandwich a region where the first electrode finger, the second electrode finger, and the third electrode finger are provided in an electrode finger orthogonal direction.