FBAR Oscillator Stabilized by Rb Atomic Resonator for SHF/EHF-Band Wireless Devices

We propose an FBAR oscillator for the wireless system used in the superhigh-frequency (SHF) band or extremely high-frequency (EHF) band. At these frequencies, a high-precision standard clock is required, and it is preferable that the clock frequency be set to a GHz-order band to mitigate the amount of frequency multiplication. In this study, we developed a 3.5 GHz band thin-film bulk acoustic resonator (FBAR)oscillator and stabilized it to the hyperfine transition of alkali atoms⁸⁷Rb. Consequently, a short-term frequency instability of 8.5 ⨯ 10−¹² at 1s was achieved.