33 GHz Overmoded Bulk Acoustic Resonator

This paper reviews the latest developments in microwave acoustic wave devices. After an introduction and brief history of bulk acoustic wave (BAW) and surface acoustic wave (SAW) devices, a review is given for guided SAWs and XBARs -two new technologies, which are promising for future 5G applications. Following this, we discuss recent simulation techniques, such as 3D finite element method (3D FEM) and simulation of nonlinearities, as well as filter synthesis. Next, a review on tunable and reconfigurable acoustics is given. Finally, we present the latest developments in microwave acoustics for millimeter-wave (mm-wave) operation as well as BAW oscillators.INDEX TERMS Bulk acoustic wave (BAW) devices, filter, filter-synthesis, front-end, high power, MTT 70th Anniversary Special Issue, multiplexer, nonlinearity, resonator, surface acoustic wave (SAW) devices.

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“…In other words, it is optimal to have the ratio between piezoelectric stress coefficient and permittivity spatially correlated to the strain profile of the desired mode, as is discussed in existing designs [1], [2], [4], [5]. Therefore, when designing multilayer structures, it is preferable to have the material interfaces placed at the zero strain locations, resulting in half wavelength per layer at the eigenfrequency ω i (the parallel resonance frequency).…”

Section: A Electrical Excitation Of Vibrations In An Fbarmentioning

confidence: 99%

“…Recent efforts in pushing the maximum operating frequencies of FBARs demonstrate that another approach is to use a higher order mode in an FBAR where a boost in electromechanical coupling coefficient is achieved with forward and reverse axis piezoelectric layers [2]- [4]. A previous work observed through simulations that for these resonators with thick electrodes, low characteristic acoustic impedance are preferred in electrodes in an overmoded structure [1]. Other works discussed mode selection in a multilayer structure with alternating polarities of identical piezoelectric layers but simplified the contribution of electrodes in their discussions [5].…”

Section: Introductionmentioning

confidence: 99%

Electrode Effects in mmWave Frequency Multilayer Bulk Acoustic Wave Resonators

Peng¹

2023

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<p>Electrodes are present in acoustic resonators to set electrical boundary conditions. Electrodes are acoustically part of a bulk acoustic wave (BAW) resonator that affect both its electromechanical coupling coefficient and its quality factor. Calculation of electromechanical coupling coefficient in multilayer structures requires the analysis of a system of equations relating the waves inside each layer to those in its adjacent layers. In this work, layer thicknesses and material constants in each layer are used to calculate the series and parallel resonance frequencies. Due to the proximity in frequency of series and parallel resonance, a series expansion of the series resonance frequency equation is performed around the parallel resonance frequency, and a closed form expression for electromechanical coupling coefficient from material constants and layer thicknesses is obtained to facilitate the observation of the electromechanical coupling coefficient effects of electrodes. Thermoelastic damping (TED) has been identified as the dominant acoustic loss mechanism in conductors. In this work, the complex wavenumber is calculated based on the unified theory of thermoelasticity to incorporate acoustic loss due to the interaction between elastic deformation and heat flow. Acoustic quality factors due to TED for common metals in microelectromechanical systems (MEMS) processing are calculated to facilitate the observation of the quality factor effects of electrodes. It is observed that there exists tradeoff among electromechanical coupling coefficient, acoustic quality factor, and electrical conductivity in the selection of electrode metals.</p>

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“…Enhancing electromechanical coupling coefficient in such FBARs is currently done through a maximal modal excitation approach. One single-piezoelectric layer design is to make the top and bottom electrodes and the piezoelectric half wavelength thick [1]. Recent efforts in pushing the maximum operating frequencies of FBARs demonstrate that another approach is to use a higher order mode in an FBAR where a boost in electromechanical coupling coefficient is achieved with forward and reverse axis piezoelectric layers [2]- [4].…”

Section: Introductionmentioning

confidence: 99%

Electrode Effects in mmWave Frequency Multilayer Bulk Acoustic Wave Resonators

Peng¹

2023

Preprint

0

View full text Add to dashboard Cite

<p>Electrodes are present in acoustic resonators to set electrical boundary conditions. Electrodes are acoustically part of a bulk acoustic wave (BAW) resonator that affect both its electromechanical coupling coefficient and its quality factor. Calculation of electromechanical coupling coefficient in multilayer structures requires the analysis of a system of equations relating the waves inside each layer to those in its adjacent layers. In this work, layer thicknesses and material constants in each layer are used to calculate the series and parallel resonance frequencies. Due to the proximity in frequency of series and parallel resonance, a series expansion of the series resonance frequency equation is performed around the parallel resonance frequency, and a closed form expression for electromechanical coupling coefficient from material constants and layer thicknesses is obtained to facilitate the observation of the electromechanical coupling coefficient effects of electrodes. Thermoelastic damping (TED) has been identified as the dominant acoustic loss mechanism in conductors. In this work, the complex wavenumber is calculated based on the unified theory of thermoelasticity to incorporate acoustic loss due to the interaction between elastic deformation and heat flow. Acoustic quality factors due to TED for common metals in microelectromechanical systems (MEMS) processing are calculated to facilitate the observation of the quality factor effects of electrodes. It is observed that there exists tradeoff among electromechanical coupling coefficient, acoustic quality factor, and electrical conductivity in the selection of electrode metals.</p>

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33 GHz Overmoded Bulk Acoustic Resonator

Cited by 35 publications

References 17 publications

From Microwave Acoustic Filters to Millimeter-Wave Operation and New Applications

From Microwave Acoustic Filters to Millimeter-Wave Operation and New Applications

Electrode Effects in mmWave Frequency Multilayer Bulk Acoustic Wave Resonators

Electrode Effects in mmWave Frequency Multilayer Bulk Acoustic Wave Resonators

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