Thermally compensated ZnO film bulk acoustic resonator for RF application above 5GHz frequency

We present a study of the effect of introducing two-series air gap capacitor and tailoring the oxide in thin-film bulk acoustic resonator (FBARs) for thermal compensation at a frequency > 5 GHz. This approach reduces the temperature coefficient of frequency value of ZnO FBAR upto 0.011 ppm/? C within the industrial temperature range at 5.45 GHz frequency. The quality factor of the compensated FBARs is 1100 with a motional impedance of 38 O. This exceeds significantly the qual-ity factor of uncompensated FBARs (similar to 120). Additionally, we report on the stress and strain required to obtain an optimal design of compensated FBARs.

Automated summary

In this study, we investigate the impact of introducing two-series air gap capacitor and tailoring oxide in thin-film bulk acoustic resonator (FBARs) for thermal compensation at a frequency higher than 5 GHz. This approach reduces the temperature coefficient of frequency of ZnO FBAR to 0.011 ppm/°C within the industrial temperature range at 5.45 GHz. The compensated FBARs exhibit a higher quality factor of 1100 and a motional impedance of 38 O, which significantly surpasses the quality factor of uncompensated FBARs (approximately 120). We also analyze the stress and strain required to achieve an optimal design of compensated FBARs.