The power flow angle of acoustic waves in thin piezoelectric plates

IEEE Trans. Microwave Theory Techn.

et al. 2020

We present the first group of acoustic delay lines (ADLs) at 5 GHz, using the first-order antisymmetric (A1) mode in Z-cut lithium niobate thin films. The demonstrated ADLs significantly surpass the operation frequency of the previous works with similar feature sizes, because of its simultaneously fast phase velocity, large coupling coefficient, and low-loss. In this work, the propagation characteristics of the A1 mode in lithium niobate is analytically modeled and validated with finite element analysis. The design space of A1 ADLs is then investigated, including both the fundamental design parameters and those introduced from the practical implementation. The implemented ADLs at 5 GHz show a minimum insertion loss of 7.9 dB, an average IL of 9.1 dB, and a fractional bandwidth around 4%, with delays ranging between 15 ns to 109 ns and the center frequencies between 4.5 GHz and 5.25 GHz. The propagation characteristics of A1 mode acoustic waves have also been extracted for the first time. The A1 ADL platform can potentially enable wide-band high-frequency passive signal processing functions for future 5G applications in the sub-6 GHz spectrum bands.

Section: B In-plane Orientation Of A1 Acoustic Delay Linesmentioning

confidence: 99%

Section: B In-plane Orientation Of A1 Acoustic Delay Linesmentioning

confidence: 99%

Section: B In-plane Orientation Of A1 Acoustic Delay Linesmentioning

confidence: 99%

See 1 more Smart Citation

5-GHz Antisymmetric Mode Acoustic Delay Lines in Lithium Niobate Thin Film

IEEE Trans. Microwave Theory Techn.

et al. 2020

“…The second reason for the selected orientation is to attain a small power flow angle (PFA) for SH0 so that longer delay ADLs can be attained [47]. The PFA is defined as the angle between the phase velocity and the group velocity (pointing to the phase velocity).…”

Section: A Unidirectional Acoustic Delay Line Overviewmentioning

confidence: 99%

GHz Broadband SH0 Mode Lithium Niobate Acoustic Delay Lines

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

et al. 2020

We present the first group of GHz broadband SH0 mode acoustic delay lines (ADLs). The implemented ADLs adopt unidirectional transducer designs in a suspended X-cut lithium niobate thin film. The design space of the SH0 mode ADLs at GHz is first theoretically investigated, showing that the large coupling and sufficient spectral clearance to adjacent modes collectively enable the broadband performance of SH0 delay lines. The fabricated devices show 3-dB fractional bandwidth ranging from 4% to 34.3% insertion loss between 3.4 and 11.3 dB. Multiple delay lines have been demonstrated with center frequencies from 0.7 to 1.2 GHz, showing great frequency scalability. The propagation characteristics of SH0 in lithium niobate thin film are experimentally extracted. The demonstrated ADLs can potentially facilitate broadband signal processing applications.

“…First, we assume plane wave characteristics in the ADL waveguide. It is based on the fact that our ADL aperture is significantly longer than the lateral wavelength, and these Lamb waves have zero power flow angle (angle between the phase and group velocities [54]) along X-axis and Y-axis in Z-cut LiNbO 3 [40]. The minor wave diffraction and loss near the busline and release window regions might cause a slight underestimation of the acoustic Q.…”

Section: Discussionmentioning

confidence: 99%

Acoustic Loss of GHz Higher-Order Lamb Waves in Thin-Film Lithium Niobate: A Comparative Study

J. Microelectromech. Syst.

Gong

2021

This work reports a comparative study of acoustic loss between different Lamb waves at GHz in thin-film lithium niobate (LiNbO 3 ). The propagation loss (PL) of higher-order Lamb waves in thin-film LiNbO 3 is studied for the first time using acoustic delay line (ADL) testbeds. The acoustic wave attenuation and quality factors ( Q) of different Lamb waves are extracted, showing higher Qs for higher-order Lamb modes than fundamental modes in air and vacuum at room temperature. The extracted Qs are higher than those reported in thin-film LiNbO 3 resonators, implying the electrode and anchor-induced loss as the dominant loss factors. The ADL-based loss analysis framework is readily extendable to acoustic damping study in other microwave acoustic platforms.