scholarly journals Enhanced tunable performance of high Q-factor BaxSr1−xTiO3 film bulk acoustic wave resonators

2013 ◽  
Vol 5 (3) ◽  
pp. 361-369 ◽  
Author(s):  
Andrei Vorobiev ◽  
Spartak Gevorgian
Keyword(s):  
Acoustic Wave ◽  
Resonance Frequency ◽  
Coupling Coefficient ◽  
Piezoelectric Effect ◽  
Bulk Acoustic Wave ◽  
Electromechanical Coupling Coefficient ◽  
Q Factor ◽  
High Q ◽  
Series Resonance ◽  
Film Bulk

Emerging intrinsically tunable film bulk acoustic wave(BAW) resonators allow the development of new generation reconfigurable and agile microwave circuits. In this paper, we demonstrate the enhancement of tunable performance of the high Q-factor BaxSr1−xTiO3 BAW – solidly mounted resonators (BAW–SMR) by varying Ba concentration. The Ba0.5Sr0.5TiO3 BAW–SMR reveal tunability of series resonance frequency up to 2.4%, electromechanical coupling coefficient up to 7.5% and rather high Q-factor, up to 250 at 5.3 GHz. Correlations between the measured electroacoustic parameters are analyzed using the theory of dc field-induced piezoelectric effect in paraelectric phase ferroelectrics. Higher coupling coefficient and tunability of resonance frequency of the Ba0.5Sr0.5TiO3 BAW–SMR are associated with higher tunability of permittivity. Strong anisotropy in field-induced piezoelectric effect is predicted with highest coupling coefficient in (001) direction of the BaxSr1−xTiO3 films. It is also shown that the tunability of series resonance frequency of Ba0.5Sr0.5TiO3 BAW–SMR is limited by relatively high and negative nonlinear electrostriction coefficient which is found to be m ≈ −4·1010 m/F. The BAW–SMR Q-factor is limited significantly by extrinsic acoustic loss associated with wave scattering at reflection from relatively rough top interface. The results of analysis show possible ways of further improvement of the performance of tunable BAW–SMR.

Q-Factor Improving of Film Bulk Acoustic Wave Resonator for Chip-Scale Atomic Clocks

2015 ◽  
Vol 645-646 ◽  
pp. 509-512 ◽  
Author(s):  
Zhong Shan Zhang ◽  
Liang Tang ◽  
Lei Ji
Keyword(s):  
Acoustic Wave ◽  
Resonant Frequency ◽  
Piezoelectric Layer ◽  
Bulk Acoustic Wave ◽  
Atomic Clocks ◽  
Q Factor ◽  
Silicon Oxide Layer ◽  
Electrode Layer ◽  
Composite Support ◽  
Film Bulk

Film bulk acoustic wave resonators (FBARs) with relatively high Q-factor are considered good candidates to be used in the RF module of chip-scale atomic clocks (CSACs). In order to simulate and analyze the resonant properties, the Mason equivalent circuit of the FBAR device is introduced, which consists of five parts including top electrode layer, low temperature silicon oxide layer, piezoelectric layer, bottom electrode layer and a composite support structure layer. With the practical processing conditions considered, the piezoelectric layer with a reasonable thickness of 1.30um is selected to achieve a FBAR device with resonant frequency 4.60GHz and Q-factor 278 by the simulation and analysis. In order to further improve the Q-factor, SiO2 thin films with thicknesses from 0.10um to 0.50um placed between the top electrode and piezoelectric layer are introduced. However, as the SiO2 thin film is introduced, the resonant frequency of the FBAR device will drop. In order to keep the resonant frequency fixed to 4.60GHz, the thickness of the piezoelectric layer is adjusted. Finally, the FBAR device resonating at 4.60GHz with Q-factor 627 is achieved, the thicknesses of the SiO2 film and piezoelectric layer of which are 0.20um and 0.69um respectively. The Q-factor of the FBAR device improves about 350, and the FBAR device is expected to be used in CSACs.

Design and Simulation of Film Bulk Acoustic Wave Resonator in Ku-Band

2013 ◽  
Vol 662 ◽  
pp. 556-561 ◽  
Author(s):  
Nurul Izza Mohd Nor ◽  
Kriyang Shah ◽  
Jugdutt Singh ◽  
Zaliman Sauli
Keyword(s):  
Acoustic Wave ◽  
Fem Simulation ◽  
Bulk Acoustic Wave ◽  
Three Dimension ◽  
Series Resonance ◽  
Bulk Acoustic Wave Resonator ◽  
Wave Resonator ◽  
Film Bulk ◽  
The One ◽  
Ku Band

This paper presents the design of a Film Bulk Acoustic Wave Resonators (FBARs) operating in Ku-band. The one-dimensional (1-D) numerical and the three-dimension (3-D) Finite Element Method (FEM) simulation results are analysed and compared. The results show that coupling coefficient (k2eff) up to 6.5% can be obtained with optimised thickness ratio of electrode/piezoelectric layers of operating frequencies greater than 15GHz. The FBARs have areas of 1.69x10-4µm2and 7.84x10-4µm2for series resonance frequency of 14.7GHz and 15.9GHz respectively and achieves quality (Q) factor of 300. The designed FBAR filter operating in Ku-band has the centre frequency of 15.5 GHz, the insertion loss of 3.5dB, out-of-band rejection of 13dB and fractional bandwidth of 6.6%.

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