Search for: All records

This paper presents the first voltage-controlled MEMS oscillator (VCMO) based on a Lithium Niobate (LiNbO3) lateral overtone bulk acoustic resonator (LOBAR). The VCMO consists of a LOBAR in a closed loop with 2 amplification stages and a varactor-embedded tunable LC tank. By adjusting the bias voltage applied to the varactor, the tank can be tuned to change the closed-loop gain and phase responses of the oscillator so that the Barkhausen conditions are satisfied for a particular resonance mode. The tank is designed to allow the proposed VCMO to lock to any of the ten overtones ranging from 300 to 500 MHz. Owing to the high-quality factors of the LiNbO3 LOBAR, the measured VCMO shows a low close-in phase noise of -100 dBc/Hz at 1 kHz offset from a 300 MHz carrier and a noise floor of -153 dBc/Hz while consuming 9 mW. With further optimization, this VCMO can lead to direct radio frequency (RF) synthesis for ultra-low power transceivers in multi-mode Internet-of-Things (IoT) nodes. 

This work reports the first lithium niobate (LiNbO 3 ) lateral overtone bulk acoustic resonator (LOBAR) with a high figure-of-merit (FoM) for each overtone. We exploit electrode offset as a key parameter to excite both the even-order and the odd-order modes with uniform k t 2 . The fabricated device shows Qs (1966, 1215, and 1513) among the highest reported for LiNbO 3 resonators at the equally-spaced resonances (446.4, 599.8, and 757.3 MHz). As a result, high FoMs of 83.6, 102.6 and 63.1 have been obtained simultaneously for aforementioned resonances. These FoMs significantly surpass those of the state-of-the-art overtone devices. With these qualities, frequency-hopping oscillators based on LiNbO 3 LOBARs can be enabled for low power and phase-continuous frequency-hopping applications.