Multilayer SAW Resonator Duty Factors for Filter Band Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Acoustic wave devices with multilayer piezoelectric substrates face band imbalance due to manufacturing variability in interdigital transducer electrode duty factors, leading to shifts in resonant and antiresonant frequencies and passband misalignment in filters formed on the same die.
Innovation Solution
Incorporating surface acoustic wave resonators with different interdigital transducer electrode duty factors and utilizing silicon nitride trimming layers to adjust resonant frequencies and compensate for band imbalance, while forming filters with distinct target duty factors to maintain band balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If interdigital transducer electrodes are fabricated with standard manufacturing processes, then production efficiency is maintained, but manufacturing variability causes duty factor deviations and band imbalance
Solution Approach 1:
The patent changes the design parameter of duty factor from a fixed value to variable values tailored to different resonators. By assigning different target duty factors to resonators based on their resonant frequencies and positions on the substrate, the system compensates for manufacturing variability without requiring tighter process control, thus maintaining productivity while improving band balance.
Solution Approach 2:
The patent applies local quality by customizing the target duty factor for each resonator based on its specific location and resonant frequency. Instead of using a uniform duty factor across all resonators, the system tailors the duty factor locally to compensate for position-dependent manufacturing variations, achieving improved manufacturing precision without sacrificing overall production efficiency.
2Device complexity
If all resonators use the same target duty factor, then design simplicity is maintained, but passband misalignment occurs due to manufacturing variability
Solution Approach 1:
The patent implements local quality by assigning different target duty factors to different resonators based on their specific characteristics (resonant frequency, position on substrate). This localized customization ensures that each resonator's passband aligns correctly with its intended frequency range, improving reliability while the overall design framework remains relatively simple and systematic.
Solution Approach 2:
The patent changes the duty factor parameter from a constant value to a variable parameter that depends on resonator characteristics. This parameter variation allows the system to compensate for manufacturing variability and achieve accurate passband alignment across different resonators without significantly increasing design complexity.
3Measurement precision
If duty factor is increased to compensate for frequency shifts, then resonant frequency accuracy improves, but band balance deteriorates due to asymmetric effects on resonant and antiresonant frequencies
Solution Approach 1:
The patent uses parameter changes by adjusting the target duty factor to different values for different resonators. This allows precise control over the resonant frequency of each resonator while maintaining proper band balance. The systematic variation of duty factor parameters compensates for frequency shifts without causing asymmetric distortions to band balance.
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 approach effectively compensates for manufacturing variability, ensuring accurate alignment of passbands and maintaining band balance across filters formed on the same die, enhancing the operational characteristics of acoustic wave devices.
Implementation Method 1
a layer of piezoelectric material having a lower surface bonded to an upper surface of a layer of a second material different from the piezoelectric material
Implementation Method 2
first interdigital transducer electrodes having a first duty factor and disposed on a multilayer piezoelectric substrate
Implementation Method 3
utilizing silicon nitride trimming layers to adjust resonant frequencies and compensate for band imbalance
Data Source
AI summary
A die includes at least two surface acoustic wave resonators having different resonant frequencies. A first of the at least two surface acoustic wave resonators includes first interdigital transducer electrodes having a first duty factor and disposed on a multilayer piezoelectric substrate. The multilayer piezoelectric substrate a layer of piezoelectric material having a lower surface bonded to an upper surface of a layer of a second material different from the piezoelectric material. A second of the at least two surface acoustic wave resonators includes second interdigital transducer electrodes having a second duty factor different from the first duty factor and disposed on the multilayer piezoelectric substrate to improve band balance of a device formed from the at least two surface acoustic wave resonators.