The Influence of the Acoustic Reflector Design on the Temperature Coefficient of Frequency for Shear and Longitudinal Mode AlN Resonators

The property of temperature-frequency drift has an effect on the passband ripples, center frequency and insertion loss of FBAR filters, reducing the reliability of its electrical application. A temperature-frequency drift simulation of a typical Mo/AlN/Mo FBAR is achieved by means of finite element analysis software ANSYS, the simulated temperature coefficient of frequency is about-35ppm/°C within the temperature range of-50°C~150°C. By adding a compensated layer with positive temperature coefficient in the FBAR structure, the effects of the compensated layer thickness on temperature-frequency drift, resonant frequency and electromechanical coupling are analyzed. The simulated temperature coefficient of frequency of designed temperature compensated FBAR, which composed of Mo/AlN/SiO2/Mo, is about 0.8ppm/°C, the property of temperature-frequency drift is effectively improved.

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Zero Temperature Coefficient of Frequency Surface Acoustic Wave Resonator for Narrow-Duplex-Gap Application on SiO2/Al/LiNbO3Structure

Japanese Journal of Applied Physics ◽

10.1143/jjap.50.07hd13 ◽

2011 ◽

Vol 50 (7) ◽

pp. 07HD13 ◽

Cited By ~ 10

Author(s):

Hidekazu Nakanishi ◽

Hiroyuki Nakamura ◽

Tetsuya Tsurunari ◽

Joji Fujiwara ◽

Yosuke Hamaoka ◽

...

Keyword(s):

Acoustic Wave ◽

Temperature Coefficient ◽

Surface Acoustic Wave ◽

Zero Temperature ◽

Wave Resonator ◽

Temperature Coefficient Of Frequency

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On the Control of the Temperature Coefficient of Frequency of AT-Crystals

10.1109/freq.1964.199553 ◽

1964 ◽

Author(s):

C. Franx

Keyword(s):

Temperature Coefficient ◽

Temperature Coefficient Of Frequency

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The Improvement of Temperature Coefficient of Frequency in Thin Film Bulk Acoustic Wave Resonator using Secondary Harmonics

MRS Proceedings ◽

10.1557/proc-741-j10.4 ◽

2002 ◽

Vol 741 ◽

Author(s):

Yukio Yoshino ◽

Masaki Takeuchi ◽

Hajime Yamada ◽

Yoshihiko Goto ◽

Tadashi Nomura ◽

...

Keyword(s):

Thin Film ◽

Acoustic Wave ◽

Temperature Coefficient ◽

Finite Element Method Simulation ◽

Thickness Ratio ◽

Bulk Acoustic Wave ◽

Bulk Acoustic Wave Resonator ◽

Wave Resonator ◽

Film Bulk ◽

Temperature Coefficient Of Frequency

ABSTRACTWe have succeeded in making an 870MHz-range thin film bulk acoustic wave (BAW) resonator that has a small temperature coefficient of frequency (TCF) using secondary harmonics. The 870MHz-range BAW resonator has been requested to have nearly zero TCF, because it will be used in an oscillator for remote keyless entry systems. The BAW resonator has composite structure that consists of Al electrodes and ZnO/SiO2. We directed our attention to the fact that ZnO and Al have negative TCF, and SiO2 has a positive one. It is theoretically possible to make zero TCF BAW resonators by optimizing the thickness ratio of ZnO and SiO2. However, using fundamental resonance, TCF is so sensitive to the thickness ratio that it cannot be easily controlled by MEMS techniques. We founds in finite element method simulation and confirmed by experiment that the TCF of secondary harmonics has a local minimum when changing the ZnO/SiO2 thickness ratio. As the result, a nearly zero TCF resonator without strict control of ZnO/SiO2 thickness ratio has been realized by adopting Al/ZnO/SiO2/ZnO/Al/SiO2 structure and combining thermal oxidized Si and sputtered SiO2. The resonator has the TCF of -1.86ppm/degree in the range of −40 to 85 degrees centigrade.

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