5 GHz band low phase noise Si-CMOS oscillator with flip-chip mounted FBAR

Low phase noise 5 GHz oscillator is designed with 90 nm silicon complementary metal oxide semiconductor (Si-CMOS) process. To achieve low phase noise, we used high Q value film bulk acoustic resonator (FBAR) instead of conventional LC resonant circuit. FBAR was mounted by using stud bump bonding instead of wire bonding to reduce parasitic inductance. This FBAR oscillator has phase noise of lower than -108dBc/Hz at 100 kHz offset.