Acoustic Wave Element Capacitance IMD Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Acoustic wave elements, particularly in branching filters, suffer from inter-modulation distortion (IMD) and harmonic distortion due to nonlinearity, leading to a decrease in signal-to-noise ratio (SNR) and potential interference with other wireless communication systems, with existing solutions increasing the size of the resonator and acoustic wave element.
Innovation Solution
The acoustic wave element incorporates a piezoelectric substrate with comb-shaped electrodes and capacitance elements connected to the IDT, where the capacitance elements are strategically positioned to cancel out distorted signals by satisfying specific gap length and width ratios, thereby reducing the impact of IMD and harmonic distortion without increasing the size of the resonator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a resonator is divided without changing electrostatic capacity to suppress distorted waves, then the distorted wave suppression is improved, but the size of the resonator and acoustic wave element increases
Solution Approach 1:
A capacitance element is introduced as an intermediary component connected between the first and second comb-shaped electrodes. This capacitance element provides an alternative current path that reduces the voltage across the IDT, thereby suppressing distorted waves without requiring physical division of the resonator structure. The capacitance element acts as a mediator that decouples the voltage stress from the IDT while maintaining electrical connectivity.
Solution Approach 2:
The invention changes the electrical parameters of the system by adding a capacitance element with specific capacitance value. This parameter change allows the system to operate with reduced voltage across the IDT, suppressing nonlinearity and distorted wave generation. The capacitance value is carefully selected to achieve the desired voltage division effect without altering the physical dimensions of the resonator.
2Object-generated harmful factors
If the voltage applied to the resonator is dispersed to suppress distorted waves, then the distorted wave suppression is improved, but the resonator becomes larger in size
Solution Approach 1:
The capacitance element serves as an intermediary that enables voltage dispersion without physical expansion. By connecting the capacitance element between the comb-shaped electrodes, the voltage is divided between the IDT and the capacitance element, achieving the desired voltage dispersion effect while keeping the resonator footprint unchanged.
Solution Approach 2:
Instead of dispersing voltage through spatial expansion (adding more resonator elements), the invention disperses voltage through an electrical dimension by introducing a capacitance element. This allows voltage division to occur in the electrical circuit domain rather than requiring physical expansion in the spatial domain.
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 effectively suppresses distorted waves, improving the SNR and reducing the risk of interference, while maintaining a compact size by optimizing the placement and design of capacitance elements within the acoustic wave element.
Implementation Method 1
the capacitance elements are strategically positioned to cancel out distorted signals by satisfying specific gap length and width ratios
Implementation Method 2
an acoustic wave element having a piezoelectric substrate and an IDT (InterDigital Transducer) provided on a major surface of the piezoelectric substrate
Implementation Method 3
an IDT having a first comb-shaped electrode and a second comb-shaped electrode which are located on an upper surface of the piezoelectric substrate
Implementation Method 4
Transform Electrical Energy to Acoustic Energy
Data Source
AI summary
SAW element has a substrate; an IDT having a first comb-shaped electrode and a second comb-shaped electrode located on an upper surface of the substrate; and a capacitance element located on the upper surface of the substrate. The capacitance element has a first counter electrode connected to the first comb-shaped electrode and a second counter electrode connected to the second comb-shaped electrode and facing the first counter electrode across a third gaps. The direction from the first counter electrode through the third gaps toward the second counter electrode is a reverse direction from the direction from the first comb-shaped electrode through the gaps toward the second comb-shaped electrode. If it is assumed that the gap and width of the gap are di and wi, and the gap and width of the third gap are Dj and Wj, the following formula holds:0<Σ(Wj/Dj2)<2Σ(wi/di2).