Biblio

This work demonstrates an ultra-compact low power oscillating micromechanical active pixel array based on a 0.35 μm back-end of line (BEOL)-embedded CMOS-MEMS technology. Each pixel consists of a 3-MHz clamped-clamped beam (CCB) MEMS resonator and a power scalable transimpedance amplifier (TIA) that occupies a small area of 70 × 60 μm2 and draws only 85 μW/pixel. The MEMS resonator is placed next to the TIA with less than 10 μm spacing thanks to the well-defined etch stops in the titanium nitride composite (TiN-C) CMOS-MEMS platform. A multiplexing phase-locked loop (PLL)-driven oscillator is employed to demonstrate the chip functionality. In particular, a nonlinear operation of the resonator tank is used to optimize the phase noise (PN) performance and Allan deviation (ADEV) behavior. The ADEV of 420 ppb averaged over best 3-pixels is exhibited based on such a nonlinear vibration operation.

This paper presents the synthesis and circuit transformations of acoustic wave filters based on a transversal arrangement of the individual resonators. This configuration allows for the synthesis of any filter response without detrimental of the limited value of the electro-acoustic coupling coefficient. The synthesis can be performed in the low-pass domain to be latter transformed into the band-pass domain. This latter step results in significant differences between the low-pass and the band-pass responses in wideband stringent filters. This work, after an initial synthesis in the low-pass domain, directly applies the pass-band circuit transformation achieving a more accurate synthesized network even for wideband filters.

Novel acoustic wave networks comprising resonators achieving prescribed coupling are proposed. The design methodology is based on classic network synthesis of doubly- and/or singly-terminated networks. The synthesis of LTE Band 25 contiguous duplexer prototype is performed and its electrical characteristics are presented.

Here, we propose a simple design approach based on metal-masked titanium dioxide nanopillars, which can realize strong Mie resonance in metasurfaces and enables light confinement within itself over the range of visible wavelengths. By selecting the appropriate period and diameter of individual titanium dioxide nanopillars, the coincidence of resonance peak positions derived from excited electric and magnetic dipoles can be achived. And the optical properties in this design have been investigated with the Finite-Difference Time-Domain(FDTD) solutions.

This work reviews various methods which improve the effective coupling coefficient ( k2eff) of non-bulk acoustic wave (BAW) aluminum nitride (AlN) based RF MEMS resonators, mainly focusing on the innovative structural design of the resonators. k2eff is the key parameter for a resonator in communication applications because it measures the achievable fractional bandwidth of the filter constructed. The resonator's configuration, dimension, material stack and the fabrication process will all have impact on its k2eff. In this paper, the authors will review the efforts in improving the k2eff of piezoelectric MEMS resonators from research community in the past 15 years, mainly from the following three approaches: coupling lateral wave with vertical wave, exciting two-dimensional (2-D) lateral wave, as well as coupling 2-D lateral wave with vertical wave. The material will be limited to AlN family, which is proven to be manageable for manufacturing. The authors will also try to make recommendations to the effectiveness of various approaches and the path forward.

This work investigates the electromechanical coupling coefficient (kt2) attained by two available piezoelectric acoustic resonator technologies relying on Aluminum Scandium Nitride (ScyAl1-yN) films to operate. In particular, by using a theoretical approach, we extracted the maximum kt2-value attainable, for different scandium-doping concentrations (from 0% to 40%), by Film-Bulk-Acoustic-Resonators (FBARs) and Cross-Sectional-Lamé-Mode Resonators (CLMRs). For the first time, we show how the use of higher scandium doping concentrations can render the kt2 of CLMRs higher (35%) than the one attained by FBARs (28%). Such a unique feature renders CLMRs as ideal candidates to form lithographically defined resonators and filters for next-generation wideband radiofrequency (RF) front-ends.

A new class of multi-band acoustic-wave-Iumped-ele-ment-resonator (AWLR)-based bandstop filters (BSFs) is reported. It is based on\$N\$multi-resonant A WLRs-shaped by\$K\$AWLRs and 2K inverters-that are connected to an all-pass network and result in\$\textbackslashtextbackslashpmbK\textbackslashtextbackslash Nˆth\$order rejection bands. The proposed concept allows the realization of multiple rejection bands with the following characteristics: i) fractional bandwidths (FBWs) larger than the electromechanical coupling coefficient\$\textbackslashtextbackslashpmbk\_tˆ\textbackslashtextbackslash 2\$of its constituent acoustic-wave resonators, ii) continuously variable and inde-pendently-controlled FBWs, iii) intrinsically-switched stopbands, and iv) an all pass state. For proof-of-concept validation purposes a dual-band prototype was designed, built, and tested. It exhibits two stopbands centered at 418 and 433 MHz that can be continu-ously-tuned in FBW (up to 7.7:1 tuning range) and in number.