10–60-GHz Electromechanical Resonators Using Thin-Film Lithium Niobate

Abstract

This work presents a new class of microelectromechanical system (MEMS) resonator toward 60 GHz for the fifth-generation (5G) wireless communications. The wide range of the operating frequencies is achieved by resorting to different orders of the antisymmetric Lamb wave modes in a 400-nm-thick Z-cut lithium niobate thin film. The resonance of 55 GHz demonstrated in this work marks the highest operating frequency for piezoelectric electromechanical devices. The fabricated device shows an extracted mechanical Q of 340 and an f × Q product of 1.87 × 10 13 in a footprint of 2 × 10 −3 mm 2. The performance has shown the strong potential of LiNbO 3 antisymmetric mode devices for front-end applications in 5G high-band.

Microwave Acoustic Devices: Recent Advances and Outlook

“…Products based on FBARs and SMRs have been placed in market places for WIFI 6 and C-V2X bands with Q in 1000s. Questions start to emerge if one can push acoustics to even higher frequencies, well over 10 GHz, 20 GHz, and perhaps even 60 GHz [97]. The need for such higher frequency acoustic devices is definitely brewing as higher frequency and higher-order multiple-input multiple-output (MIMO) or phased arrays have been envisioned.…”

L- and X-Band Dual-Frequency Synthesizer Utilizing Lithium Niobate RF-MEMS and Open-Loop Frequency Dividers

“…While Ql•f product decreases with the frequency, Qm•f product increases with the frequency. As investigated in [30], higher-order Amodes are better confined between electrodes due to the increasingly larger dispersion mismatch between metalized and un-metalized regions for higher-order modes. This feature leads to less acoustic damping loss from the electrodes and less energy loss to the supporting substrate for the higher-order modes.…”

X-Band Miniature Filters Using Lithium Niobate Acoustic Resonators and Bandwidth Widening Technique

“…Scaling SAW devices over 3.5 GHz requires a sub-200-nm width for interdigital electrodes, which leads to high loss and poor power handling. For BAW devices, efforts have been made to scale them to the X-band (8)(9)(10)(11)(12) [6], [7]. To this end, AlN thin films are thinned down to be around 175 nm, which introduces very stringent requirements on film quality and thickness uniformity [8].…”

“…One promising candidate for enabling the beyond 6-GHz miniature filters is the recently emerged antisymmetric Lamb wave devices in lithium niobate (LiNbO 3 ). The center frequency of these devices has been successfully scaled up to 60 GHz with record-breaking quality factors (Qs) by exploiting higher order modes [9]- [11]. Despite allowing the film thickness to remain unchanged, frequency scaling via increasing mode order sacrifices k 2 t .…”