A Novel Frequency Selective Device: The Stacked-Crystal Filter

Ballato, A.; Lukaszek, T.

doi:10.1109/freq.1973.199966

Cited by 30 publications

(4 citation statements)

References 5 publications

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“…Auxiliary inductors were also adopted to modify the lattice type for a large bandwidth [58]. Besides the ladder and lattice types, stacked crystal filter (SCF) [65,66] and coupled resonator filter (CRF) [67] were employed for the BAW resonators, corresponding structures are presented in Fig. 2c and d, respectively.…”

Section: Filter Topologymentioning

confidence: 99%

Surface and bulk acoustic wave resonators based on aluminum nitride for bandpass filters

Zha,

Luo,

Tao

et al. 2024

AAPPS Bull.

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Bandpass filters with high frequency and wide bandwidth are indispensable parts of the fifth-generation telecommunication technologies, and currently, they are mainly based on surface and bulk acoustic wave resonators. Owing to its high mechanical strength, excellent stability at elevated temperatures, good thermal conductivity, and compatibility with complementary metal-oxide-semiconductor technology, aluminum nitride (AlN) becomes the primary piezoelectric material for high-frequency resonators. This review briefly introduces the structures and key performance parameters of the acoustic resonators. The common filter topologies are also discussed. In particular, research progresses in the piezoelectric AlN layer, electrodes, and substrates of the resonators are elaborated. Increasing the electromechanical coupling constant is the main concern for the AlN film. To synthesize AlN in single-crystalline or poly-crystalline with a high intensity of (0002) orientation, and alloy the AlN with other elements are two effective approaches. For the substrates and bottom electrodes, lattice and thermal expansion mismatch, and surface roughness are critical for the synthesis of a high-crystal-quality piezoelectric layer. The electrodes with low electrical resistance, large acoustic-impedance mismatch to the piezoelectric layer, and low density are ideal to reduce insertion loss. Based on the research progress, several possible research directions in the AlN-based filters are suggested at the end of the paper.

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Section: Filter Topologymentioning

confidence: 99%

Surface and bulk acoustic wave resonators based on aluminum nitride for bandpass filters

Zha,

Luo,

Tao

et al. 2024

AAPPS Bull.

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“…Second-order stacked thin-film piezoelectric BAW filters have been demonstrated with narrow passbands and excellent isolation suitable for applications in which small size is critical or single-ended to differential-ended operation is desired [4, 5]. The principle of operation for these acoustically coupled filters is the same as stacked crystal filters [6]. However, the fabrication process is relatively complicated in the sense that multiple precisely controlled thin-film deposition steps are involved and thickness inaccuracy can degrade the performance of the filter.…”

Section: Introductionmentioning

confidence: 99%

High-frequency monolithic thin-film piezoelectric-on-substrate filters

Abdolvand

Ayazi

2009

Int. j. microw. wirel. technol.

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A class of micromachined acoustic filters is presented in which the number of individual resonant structures is reduced to 1 (monolithic filter). This resonant structure is comprised of a stack of thin-film piezoelectric-on-silicon. Symmetric and anti-symmetric resonance modes (dual modes) of the silicon structure are piezoelectrically excited and coupled to realize a 2-pole narrowband filter. High-order lateral bulk acoustic resonance modes of a rectangular plate are utilized to design dispersed-frequency UHF filters fabricated on a single substrate. Thickness mode filters are also realized at GHz frequencies using a new interdigitated electrode design. Additionally, it is shown that the filter bandwidth can be controlled by changing the dimensions of the resonant structure and the electrode pattern. Narrowband lateral mode filters with filter Q’s larger than 300 at ~440 MHz and thickness mode filters with filter Q’s in the range of 150–900 at ~3.1 GHz are demonstrated.

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“…The SCF is composed of multi-layers of piezoelectric and metal layers, as shown in Fig. 18a [42][43][44][45].…”

Section: Acoustically Coupled Resonator Filtersmentioning

confidence: 99%

Thin film resonator technology

Lakin¹

IEEE International Frequency Control Sympposium and PDA Exhibition Jointly With the 17th European Frequency and Time Forum, 200

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The thin film resonator technology has been under development for over forty years in one form or another. Although the basic approach is derived from the desire to reach higher frequencies than those readily achieved by thinning bulk crystals, there have always been competing technologies or fundamental material or processing problems that have impeded the development. Finally, a point was reached in the wireless market wherein competing technologies appeared unable to meet the demands of modern wireless applications and thin film approaches began to receive some emphasis. This paper will survey the thin film resonator technology. Every effort will be made to provide an objective analysis of the technology in relation to applications and competing technologies, and point out obstacles and promises, as known, for further technology advancement to high frequencies.

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A Novel Frequency Selective Device: The Stacked-Crystal Filter

Cited by 30 publications

References 5 publications

Surface and bulk acoustic wave resonators based on aluminum nitride for bandpass filters

Surface and bulk acoustic wave resonators based on aluminum nitride for bandpass filters

High-frequency monolithic thin-film piezoelectric-on-substrate filters

Thin film resonator technology

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