Biblio

The achievable bandwidth in ladder acoustic filters is strictly limited by the electromechanical coupling coefficient (k;) in conventional ladder-acoustic filters. Furthermore, their out-of-band rejection is inherently weak due to the frequency responses of the shunt or series-connected acoustic resonators. This work proposes a coupling-matrix-based solution for both issues by employing acoustic and electromagnetic resonators within the same filter prototype using prescribed Chebyshev responses. It has been shown that significantly much wider bandwidths, that cannot be achieved with acoustic-only filters, can be obtained. An important strength of the proposed method is that a filter with a particular FBW can be designed with a wide range of acoustic resonators with different k; values. An 14 % third-order asymmetrical-response filter is designed and fabricated using electromagnetic resonators and an acoustic resonator with a k; of 3.5 %.

This work presents a novel security technique using the optical hash function to create a message digest algorithm in the wavelength domain. The optical devices used for high speed and high security algorithm handling comprised a PANDA ring resonator connected with an add/drop filter system. The PANDA ring resonator was introduced to access the dynamic behavior of bright-bright soliton collision within the modified add/drop filter. Outputs of the dynamic states formed key suppression as a high security application for optical cryptography. The add/drop filter was an essential device in the proposed design for optical hash function processing. Simulation outputs proved that the proposed technique obtained optical hash function in the wavelength domain for real time message digest creation. The wavelength of the data must be within 40% of the center wavelength of the system input signal. The integrity of the data was maintained by this highly secure process.

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.

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.

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.