New piezoelectric materials for SAW filters

Adrian Anghelescu; Monica Nedelcu

doi:10.1117/12.882299

3 December 2010 New piezoelectric materials for SAW filters

Adrian Anghelescu, Monica Nedelcu

Proceedings Volume 7821, Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies V; 78210E (2010) https://doi.org/10.1117/12.882299
Event: Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies, 2010, Constanta, Romania

Abstract

Scientific research of surface acoustic wave (SAW) devices had an early start by the end of 1960s and led to the development of high frequency and small size piezo devices. A sustained effort was dedicated for these components to be transformed into many more interesting applications for telecom market. Recently the employment of new piezo materials and crystallographic orientations open new opportunities for SAW filters. New piezoelectric crystals of gallium orthophosphate (GaPO₄) provide higher electromechanical coupling than quartz, while maintaining temperature compensated characteristics similar to quartz. Based on this material phase transition of 970°C, development of new piezo devices to operate at higher temperatures up to 800°C can be done. SAW velocities about 30% lower than ST-X quartz, favors smaller and more compact devices. Other advantages of GaPO₄ are: stability with high resistance to stress induced twinning, 3~4 times higher electromechanical coupling than quartz and existence of SAW temperature compensated orientations. Another family of new materials of the trigonal 32 class has received much attention recently because of their temperature behavior similar to quartz and the promise of higher electromechanical coupling coefficients. It is the family of langasite (LGS, La₃Ga₅SiO₁₄), langatate (LGT, La₃Ga_5.5Ta_0.5O₁₄) and langanite (La₃Ga₅.5Nb_0.5O₁₄). Langasite crystals, easier to obtain and with the value of electromechanical coupling coefficient intermediate between quartz and lithium tantalate (k²=0.32% for 0°, 140°, 22.5° orientation and k²=0.38% for 0°, 140°, 25° orientation), enable us to design SAW filters with a relative pass band of 0.3% to 0.85%. Other piezoelectric materials are reviewed for comparison.

Citation Download Citation

Adrian Anghelescu and Monica Nedelcu "New piezoelectric materials for SAW filters", Proc. SPIE 7821, Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies V, 78210E (3 December 2010); https://doi.org/10.1117/12.882299

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available