A 2.4-GHz Cryogenic CMOS Oscillator Based on FBAR Resonator for Quantum Computing Applications

This study compares the performance of a 2.4-GHz FBAR resonator and the CMOS oscillator based on it operating at 4.2 K and 300 K, respectively, providing the first reference for CMOS-FBAR oscillators operating at cryogenic temperature (CT). When the temperature drops to 4.2 K, the quality factor (Q) of the resonator increases mainly due to the decrease of parasitic resistance in the electrodes. However, the overall phase noise of the oscillator gets worse at cryogenic temperature, mainly due to the increase in flicker noise of the CMOS circuit. By comparison, the FBAR oscillator exhibits superior performance than LC oscillators at cryogenic temperature, making it suitable for quantum computing applications.