High-Q Resonator-Inductor Using LiNbO3 Plate for Frequency Tuning in 1-5 GHz.

In this article, a new high quality factor ( Q ) inductor with piezoacoustic plate acoustic wave (PAW) resonators is presented. As indicated by the investigation of the acoustic wave propagation characteristics and transducer materials, the coupling coefficient ( k2 ) of the shear-horizontal plate (SH0) mode that propagates in the LiNbO3 plate increases to 55.7%, which leads to a wide inductive bandwidth of 29%. The longitudinal and transversal spurious modes are inhibited through novel edge reflector design and transducer engineering. The peak inductor quality factor ( [Formula: see text]) of the acoustic resonator-inductor is obtained as 347, and a large range of inductance values are achieved to be up to 49 nH by regulating the interdigital transducer (IDT) number of fingers (NF). It is noteworthy that a larger inductance is realized in a more miniaturized device. Furthermore, the wavelength-scaling-induced physics is investigated for frequency tuning in 1-5 GHz, which reveals the multifrequency ability on a single chip of the SH0 acoustic resonator-inductor.

High-Frequency and Spectrum-Clean Shear-Horizontal Acoustic Wave Resonators with AlN Overlay.

By bonding the sub-wavelength-thick lithium niobate (LiNbO3) layer to high-phase-velocity (vp) substrates, such as Si, the shear-horizontal (SH) modes no longer couple with the bulk modes leaking into substrates. As the propagation loss is no longer the major concern for these types of nonleaky SH wave devices, the YX-LiNbO3 with a low rotation angle providing ultra-large coupling coefficient (keff2) can be used. In addition, by overlaying a high-velocity layer such as AlN on top of LiNbO3/Si, the vp of the SH wave can be significantly enhanced at a small cost of keff2. By a careful design of the stack, both the wide-band spurious (Lamb wave) and near-band spurious (Rayleigh wave) are suppressed successfully. This paper focuses on the design of layered substrate not only to optimize its resonance characteristics-series frequency (fs), quality factor (Q), keff2, and temperature coefficient of frequency (TCF)-but also for eliminating the out-of-band spurious responses. The optimized substrate design demonstrates the minimal propagation loss, high fs of 3 GHz, large keff2 of 14.4% and a spurious-free response at 0-6 GHz. These novel nonleaky SH wave devices can potentially enable the low loss and wideband processing functions, which is promising for the 5G/6G radio frequency (RF) communication systems.

Concentric Split Aluminum with Silicon-Aluminum Nitride Annular Rings Resonators.

This paper presents a novel approach of annular concentric split rings microelectromechanical resonators with tether configuration to reduce anchor loss and gives very high-quality factor (Q) 2.97 Million based on FEA (Finite Element Analysis) simulation. The operating frequencies of these resonators are 188.55 MHz to 188.62 MHz. When the proposed SR (square rectangle) hole shaped one dimensional phononic crystal (1D PnC), and two dimensional phononic crystal (2D PnC) structure consist of very wide and complete band gaps is applied to novel design rings MEMS resonators, the quality factor (Q) further improved to 19.7 Million and 1750 Million, respectively, by using the finite element method. It is also observed that band gaps become closer by reducing the value of filling fraction, and proposed SR PnC gives extensive peak attenuation. Moreover, harmonic response of ring resonator is verified by the perfect match layers (PML) technique surrounded by resonators with varying width 1.5λ, and 3λ effectively reduce the vibration displacement.

Spider Web-Like Phononic Crystals for Piezoelectric MEMS Resonators to Reduce Acoustic Energy Dissipation.

Phononic crystals (PnC) are a remarkable example of acoustic metamaterials with superior wave attenuation mechanisms for piezoelectric micro-electro-mechanical systems (MEMS) resonators to reduce the energy dissipation. Herein, a spider web-like PnC (SW-PnC) is proposed to sufficiently isolate the wave vibration. Finite-element analysis is performed to gain insight into the transmission property of finite PnC, and band characteristics by infinite periods. In comparison with the circle hole PnC at a similar bandgap, due to its already very lightweight PnC structure compared with previously reported PnCs, the proposed PnC offers a significantly lighter weight, smaller lattice constant, and greater energy leakage inhibition. More specifically, the resonator with the SW-PnC plate as the anchoring substrate exhibited a quality factor as high as 66569.7 at 75.82 MHz.