This paper presents a new class of monolithic integrated RF passive components based on the recently developed aluminum nitride (AlN) MEMS cross-sectional Lamé-mode resonator (CLMR) technology. First, we experimentally demonstrate a 920-MHz CLMR showing the values of electromechanical coupling coefficient (k _t ² ) and quality factor (Q _load ) in excess of 6.2% and 1750, respectively. To the best our knowledge, the resulting figure of merit (= Q·k _t ² ), in excess of 108, is the highest ever reported for AlN-based piezoelectric resonators using interdigitated metallic electrodes (IDTs) and operating in the same frequency range. Second, we report the measured performance of an 870-MHz ladder filter, synthesized using three degenerate CLMRs. This device shows the values of fractional bandwidth (BW _3dB ) in excess of 3.8% and an insertion loss of ~1.5 dB. Finally, we report the performance of the first piezoelectric transformer (PT) based on the CLMR technology. This device, dubbed “cross-sectional Lamé-mode transformer,” exploits the high-k _t ² of the CLMR technology to achieve high values of open-circuit voltage-gains (G _v ) in excess of 39. To the best of our knowledge, such a high G _v -value is the highest ever reported for MEMS-based PTs operating in the microwave frequency range.

This work presents a new acoustic MEMS resonator technology, dubbed Aluminum Nitride (AlN) Combined Overtone Resonator (COR), capable of addressing the filter requirements for the 5G high frequency bands in the 6-40GHz range. The COR exploits the multimodal excitation of two higher-order Lamb waves (2nd and 3rd order Asymmetrical Lamb Waves) in a suspended thin-film AlN plate to transduce a 2-dimensional vibration mode with high electromechanical coupling coefficient kt² (up to 1.9%) and quality factor Q>1100 at twice the frequency of a fundamental thickness-extensional mode in the same structure. Analytical and finite-element method (FEM) models are developed to describe the working principle of the COR technology and predict the achievable kt², Q and lithographic frequency tunability. An 8.8 GHz COR prototype was fabricated showing a high kt² ~ 0.3% (using a simple top-electrode-only configuration with a 2-mask process) and a groundbreaking Q~1100 which is the highest ever achieved among piezoelectric resonators above 6 GHz. The f-Q product ~ 1x 10¹³ is the highest among all demonstrated piezoelectric resonators with metallic coverage >50%. Additionally, the capability of the COR technology to deliver contiguous filters with bandwidths between 355 and 592 MHz (aggregated BW >2GHz) in the mmWave spectrum, with relaxed lithographic requirements, is demonstrated by FEM. [2019-0229]

This work demonstrates for the first time an acoustic duplexer based on Aluminum Nitride pMUTs as radiating elements. The duplexer has the function of efficiently separating independent data-streams coming from the transmit and receive modules while minimizing the noise injected in the channel through the achievement of large out-of-band rejections. As a result, this permits to reach levels of Bit-Error-Rates (BER)that are comparable to those achieved through the use of commercial Lead Zirconate Titanate (PZT)transducers. Furthermore, the simultaneous use of two communication bands allows much higher data-rates than traditional resonant approaches, thus enabling much larger data throughput.

Wirelessly networked systems of underwater devices are becoming the basis of many commercial, scientific, and military applications. In spite of increased attention in the last few years, underwater wireless networking technology still suffers from major limitations, including severe hardware dependence. In this paper, we introduce the SEANet Project, an NSF-funded effort that aims at developing a new generation of programmable platforms and a networking testbed to enable the vision of a programmable Internet of Underwater Things (IoUT). SEANet will be based on new software-defined platforms based on an open architecture to enable the flexibility to define, add, update, and swap new components in both hardware and software. SEANet is designed to support data rates at least one order of magnitude higher than existing commercial platforms over short and moderate range links. Moreover, the SEANet project will explore the design of new custom-designed ultra-wide band Microelectromechanical systems (MEMS) transducers that allow operating over much wider acoustic bandwidth (i.e., 0.01.-2 MHz) than possible with bulk piezoelectric transducers. We present a set of preliminary experiments showing that SEANet can outperform existing software-defined radio SDR-based acoustic modems based on a commercial off-the-shelf (COTS) SDR platforms. We also demonstrate the real-time reconfiguration capability of SEANet and preliminary performance of the MEMS transducers.

This letter reports on the first demonstration of ladder filters based on the recently demonstrated cross-sectional Lamé mode resonator (CLMR) technology. These filter prototypes show a fractional bandwidth (BW _3dB ) as high as 3.3% and an insertion loss as low as 0.4 dB. As the resonance frequency of CLMRs can be lithographically controlled without significantly degrading their electromechanical coupling coefficient (k ² _t ), multiple contiguous frequency bands can be covered by this filter technology without adding fabrication complexity. This unique feature addresses one of the most crucial challenges associated with the development of miniaturized mobile platforms adopting carrier-aggregation. Furthermore, the capability of achieving large BW3dB, around lithographically defined center frequencies, enables the fabrication of transmit and receive modules of the next-generation radio-frequency front ends on the same chip without adding fabrication steps.

We experimentally demonstrate a new class of micro-electro-mechanical system (MEMS) resonators, aluminum nitride (AlN) Combined Overtone Resonators (CORs). AlN CORs utilizing a combination of the $2^{{n}{d}}$ (A2) and $3^{{r}{d}}$ (A3) order asymmetrical Lamb-wave overtone at 8.8 GHz are built using one-micron aluminum nitride plates fabricated with a simple 2-mask process. Mechanical quality factor Q m and loaded quality factor Qi as high as 1100 and 750 are achieved (corresponding to $f^{\star}Q_{m}$=9.7e12 and $f^{\star}$Qr-6.6e12), being the highest reported for piezoelectric MEMS resonators operating in X band and higher bands. Those devices show near 50 $\Omega$ termination impedances (56 $\Omega$), low motional resistance R m values (20 $\Omega$) and an electromechanical-coupling coefficient k ² of 0.3%. Frequency tuning capability by varying pitch size is also demonstrated. Low- cost X band narrow band filters and oscillators can be easily built using such a new resonator technology with relaxed photolithography requirements and simple fabrication processes.