Series Acoustic Resonator Layout for Secondary Distortion Suppression
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Solution Overview
Problem
Surface acoustic wave devices with piezoelectric thin film resonators experience secondary distortion due to non-linearity, particularly when connected in series, leading to local deterioration of distortion at antiresonant frequencies.
Innovation Solution
The acoustic wave device connects two resonators in series, where the electrode of the second resonator has an electric potential identical to the first resonator, and adjusts the antiresonant frequency of the second resonator to be lower than the first, sharing a common electrode or extending the piezoelectric substance to cancel out secondary distortion voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If two resonators are connected in series with identical electric potentials at corresponding electrodes to reduce secondary distortion, then secondary distortion is reduced, but local deterioration of distortion occurs at antiresonant frequencies
Solution Approach 1:
The patent changes the antiresonant frequency parameter of the second resonator to be lower than that of the first resonator. This parameter adjustment prevents the simultaneous occurrence of antiresonant frequencies in both resonators, thereby avoiding local deterioration of distortion at antiresonant frequencies while maintaining the series connection configuration with identical electric potentials
Solution Approach 2:
The patent introduces asymmetry in the antiresonant frequency characteristics between the two series-connected resonators. By making the antiresonant frequency of the second resonator different from (lower than) that of the first resonator, the system avoids symmetric reinforcement of distortion at the same frequency points, thus preventing local deterioration
2Reliability
If the antiresonant frequency of the second resonator is adjusted to be lower than the first resonator, then local deterioration at antiresonant frequencies is prevented, but additional design complexity is introduced
Solution Approach 1:
The patent applies parameter changes by adjusting the antiresonant frequency of the second resonator to be lower than the first. This can be achieved through modifying physical dimensions, material properties, or structural characteristics of the second resonator, providing a straightforward design guideline that reduces complexity compared to more complex frequency matching approaches
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 reduces secondary distortion by aligning electric potentials and adjusting antiresonant frequencies, improving the harmonic cancellation and reducing local distortion at resonant frequencies.
Implementation Method 1
a piezoelectric substance sandwiched between a lower electrode and an upper electrode have drawn attention as elements having good characteristics at high frequencies
Implementation Method 2
Surface acoustic wave devices have been conventionally used for filters and duplexers of wireless communication devices
Data Source
AI summary
An acoustic wave device includes: a first resonator that includes a first piezoelectric substance, and first lower and upper electrodes sandwiching the first piezoelectric substance in a direction of a c-axis orientation or a polarization axis of the first piezoelectric substance; and a second resonator that is located closer to a signal input terminal than the first resonator is, is connected in series to the first resonator, includes a second piezoelectric substance, and second lower and upper electrodes sandwiching the second piezoelectric substance so that an electrode in a direction of the c-axis orientation or a polarization axis of the second piezoelectric substance has an electric potential identical to an electric potential of an electrode of the first resonator in the direction of the c-axis orientation or the polarization axis of the first piezoelectric substance, and has an antiresonant frequency less than an antiresonant frequency of the first resonator.