Integrated HBAR Resonator Layout for Low Temperature Frequency Drift
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-frequency electric resonators in the 2 to 20 GHz range face challenges in achieving both high temperature stability and reduced mass and volume, with existing mechanical resonators being bulky and having limited integration due to thermal drift issues.
Innovation Solution
A high bulk acoustic resonator (HBAR) design featuring a piezoelectric transducer and acoustic substrate with specific cutting angles and materials, aligned polarization directions, and a thermo-compressible counter-electrode to minimize temperature coefficient of frequency variations, enabling improved thermal stability and integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If mechanical resonators are used for temperature stabilization, then temperature stability is improved, but mass and volume increase significantly
Solution Approach 1:
The patent replaces traditional mechanical resonators with a microstrip-based resonator design that uses electromagnetic fields instead of mechanical vibrations. This substitution eliminates the need for bulky mechanical structures while achieving the same temperature stabilization function through electromagnetic resonance in the 2-20 GHz range.
Solution Approach 2:
The invention changes the operating parameters from mechanical frequency ranges to electromagnetic frequency ranges (2-20 GHz). By operating at these higher frequencies with microstrip structures, the resonator achieves comparable temperature stability with dramatically reduced mass and volume, as the electromagnetic fields interact with the dielectric substrate rather than requiring large mechanical components.
2Stability of the object's composition
If mechanical resonators are used for temperature stabilization, then temperature stability is improved, but device volume increases
Solution Approach 1:
The patent replaces traditional mechanical resonators with a microstrip-based resonator design that uses electromagnetic fields instead of mechanical vibrations. This substitution eliminates the need for bulky mechanical structures while achieving the same temperature stabilization function through electromagnetic resonance in the 2-20 GHz range.
Solution Approach 2:
The invention transitions from three-dimensional mechanical structures to two-dimensional microstrip patterns on a dielectric substrate. This dimensional reduction allows the resonator to achieve the required temperature stability with a compact planar footprint, dramatically reducing the volume occupied by the device while maintaining the stabilization function.
3Volume of moving object
If microstrip components are used for integration, then dimensions are reduced, but thermal drift control deteriorates
Solution Approach 1:
The invention changes the operating parameters from mechanical frequency ranges to electromagnetic frequency ranges (2-20 GHz). By operating at these higher frequencies with microstrip structures, the resonator achieves comparable temperature stability with dramatically reduced mass and volume, as the electromagnetic fields interact with the dielectric substrate rather than requiring large mechanical components.
4Volume of moving object
If microstrip components are used for integration, then dimensions are reduced, but resonance quality decreases
Solution Approach 1:
The invention changes the operating parameters from mechanical frequency ranges to electromagnetic frequency ranges (2-20 GHz). By operating at these higher frequencies with microstrip structures, the resonator achieves comparable temperature stability with dramatically reduced mass and volume, as the electromagnetic fields interact with the dielectric substrate rather than requiring large mechanical components.
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 HBAR resonator achieves a temperature coefficient of frequency with an absolute value of less than 20 ppm/K, providing enhanced thermal stability and reduced size, allowing for high-frequency operation with improved integration and reduced bulkiness.
Implementation Method 1
a piezoelectric transducer formed by a layer with a first thickness of a first material oriented along an angle φ defined by the nomenclature (YXw)/φ of the IEEE Std-176 (1949 revision) standard equal to zero, cut along a first cutting angle θ1 defined by the nomenclature (YX1)/θ of the IEEE Std-176 (1949 revision) standard, such that the electroacoustic coupling of the shear waves within that material alone is greater than 5%
Implementation Method 2
an acoustic substrate formed by a second layer with a second thickness of a second material having a working frequency acoustic quality coefficient product at least equal to 5.1012
Implementation Method 3
the relative arrangement of the transducer and the substrate is such that the direction of polarization {right arrow over (P )}A of the shearing mode of the transducer and the polarization direction {right arrow over (P)}B1 of the at least one shearing mode of the substrate corresponding to the second cutting angle θ2 are aligned, and the second cutting angle θ2 of the substrate is such that the temperature coefficient of the frequency of the corresponding first order CTFB1 is a local extremum with an absolute value of less than 20 ppm·K−1
Data Source
AI summary
The invention relates to a resonator of the high bulk acoustic resonator HBAR type, for operating at a pre-determined working frequency, comprising: a piezoelectric transducer (6), an acoustic substrate (10), a counter-electrode (8) formed by a metal layer adhering to a first face of the transducer (6) and a face of the acoustic substrate (10), and an electrode (4) arranged on a second face of the transducer (6) facing away from the first face of the transducer (6) and the substrate (10). Said resonator is characterized in that the relative arrangement of the transducer (6) and the substrate (10) is such that the polarization direction P of the shearing mode of the transducer (6) and the direction of polarization P of the at least one shearing mode of the substrate (10) corresponding to the second cutting angle θ2 are aligned, and the second cutting angle θ2 of the substrate (10) is such that the temperature coefficient of the frequency of the corresponding first order CTFB1 is a local extremum with an absolute value of less than 20 ppm·K−1, and the variation of CTFB1 from said value of Θ2 is slight with an absolute value of less than 2 ppm·K−1/degree.