Longitudinal leaky SAW resonators and filters on YZ-LiNbO/sub 3/

The high-phase velocity (above 6100 m/s in and aluminum (Al) grating on lithium niobate (LiNbO/sub 3/)) of the longitudinal leaky surface acoustic wave (SAW) (LLSAW) mode makes it attractive for application in high-frequency SAW ladder filters in the 2-5 GHz range. We investigate the dependence of one-port synchronous LLSAW resonator performance or YZ-LiNbO/sub 3/ on the metallization thickness and metallization ratio, both experimentally and theoretically. Our results indicate a strong dependence of the Q factor and resonance frequency on the aluminum thickness, with the optimal thickness that produces the highest Q values being about 8%. The optimal thickness increases with the metallization ratio. The observed behavior is interpreted with the help of simulations using a combined finite element method (FEM)/boundary element method (BEM) technique. As an application, bandpass filters have been fabricated in the 2.8 GHz frequency regime, based on LL-SAWs. The synchronous resonators constituting the ladder filters operate in the fundamental mode. The filters feature low insertion losses below 3 dB and wide relative passbands of 4.5-5%.

[1]  L. Kopp,et al.  FEM/BEM simulation and experimental study of LLSAW resonator characteristics on YZ-LiNbO/sub 3/ , 2002, 2002 IEEE Ultrasonics Symposium, 2002. Proceedings..

[2]  R. Holland,et al.  Representation of Dielectric, Elastic, and Piezoelectric Losses by Complex Coefficients , 1967, IEEE Transactions on Sonics and Ultrasonics.

[3]  N. Naumenko,et al.  High-velocity surface acoustic waves in diamond and sapphire with zinc oxide film , 1999 .

[4]  T. Makkonen,et al.  Existence of harmonic metal thickness mode propagation for longitudinal leaky waves , 2004, IEEE Ultrasonics Symposium, 2004.

[5]  K. Shibata,et al.  1.9-GHz-Band Surface Acoustic Wave Device Using Second Leaky Mode on LiTaO3 , 1996 .

[6]  T. Sato,et al.  SAW device applications of longitudinal leaky surface waves on lithium tetraborate , 1998, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[7]  M. Hikita,et al.  Propagation characteristics of longitudinal leaky SAW in Al-grating structure , 1997, 1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118).

[8]  Leaky SAW in an isotropic substrate with thick electrodes , 2001, 2001 IEEE Ultrasonics Symposium. Proceedings. An International Symposium (Cat. No.01CH37263).

[9]  J. Kaitila,et al.  Thin film bulk acoustic wave filter , 2002, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[10]  T. Makkonen,et al.  Surface-acoustic-wave devices for the 2.5–5 GHz frequency range based on longitudinal leaky waves , 2003 .

[11]  M. Solal,et al.  Fundamental mode 5 GHz surface-acoustic-wave filters using optical lithography , 2003 .

[12]  T. Sato,et al.  Propagation properties of longitudinal leaky surface waves on lithium tetraborate , 1998, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[13]  F. Hickernell,et al.  The experimental and theoretical characterization of the SAW propagation properties for zinc oxide films on silicon carbide , 2000, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[14]  V. I. Grigorievski.  Fast leaky surface acoustic waves on lithium niobate and lithium tantalate , 2000, 2000 IEEE Ultrasonics Symposium. Proceedings. An International Symposium (Cat. No.00CH37121).

[15]  J. Koskela,et al.  SAW/LSAW COM parameter extraction from computer experiments with harmonic admittance of a periodic array of electrodes , 1999, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[16]  Marc Solal,et al.  Numerical methods for SAW propagation characterization , 1998, 1998 IEEE Ultrasonics Symposium. Proceedings (Cat. No. 98CH36102).

[17]  T. Sato,et al.  Propagation of longitudinal leaky surface waves under periodic metal grating structure on lithium tetraborate , 1998, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[18]  Clemens Ruppel,et al.  Improved material constants for LiNbO/sub 3/ and LiTaO/sub 3/ , 1990, IEEE Symposium on Ultrasonics.

[19]  Alexei A. Maradudin,et al.  Leaky surface‐elastic waves on both flat and strongly corrugated surfaces for isotropic, nondissipative media , 1983 .

[20]  M. P. D. Cunha.  High velocity pseudo surface waves (HVPSAW): further insight , 1996 .

[21]  Didenko,et al.  "Fast" quasilongitudinal sagittally polarized surface waves in layer-substrate structures , 2000, The Journal of the Acoustical Society of America.