Research in Nonlinearity of Surface Acoustic Wave Devices

With the in-depth advancement of the fifth generation (5G) mobile communication technology, the technical requirements for filters are also constantly improving. Surface acoustic wave (SAW) filters are widely used in home TV, mobile communications, radio frequency filters and radar due to their simple structure, few mask layers, easy miniaturization, and low cost. Through the continuous improvement of communication technology, SAW has developed into various high-performance acoustic filters from bulk SAW with the support of some new architectures, new materials and advanced modeling techniques. This paper analyzes and reviews the research situation of SAW filter technology.

Section: Sawmentioning

confidence: 99%

Development and Application of SAW Filter

Chen

Zhu

2022

“…With the arrival of Fifth Generation (5G) mobile communication, traditional acoustic resonators, mainly surface acoustic wave (SAW) and bulk acoustic wave (BAW) resonators, face higher technical challenges. The frequency of SAW resonators is limited by the accuracy of lithography, making it difficult to meet high-frequency application scenarios above 3 GHz [ 6 , 7 , 8 , 9 , 10 , 11 ]. In contrast, the frequency of BAW resonators is determined by the AlN piezoelectric film thickness, enabling higher frequencies to be achieved by controlling the film thickness, but it still cannot meet the demand for a broad bandwidth in 5G mobile communication because of the limited electromechanical coupling coefficient ( K 2 ) of AlN [ 12 , 13 , 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Partially Etched Piezoelectric Film Filled with SiO2 Structure Applied to A1 Mode Resonators for Transverse Modes Suppression

Yu,

Guo,

et al. 2023

With the arrival of the Fifth Generation (5G) communication era, there has been an urgent demand for acoustic filters with a high frequency and ultrawide bandwidth used in radio-frequency (RF) front-ends filtering and signal processing. First-order antisymmetric (A1) lamb mode resonators based on LiNbO3 film have attracted wide attention due to their scalable, high operating frequency and large electromechanical coupling coefficients (K2), making them promising candidates for sub-6 GHz wideband filters. However, A1 mode resonators suffer from the occurrence of transverse modes, which should be addressed to make these devices suitable for applications. In this work, theoretical analysis is performed by finite element method (FEM), and the admittance characteristics of an A1 mode resonator and displacement of transverse modes near the resonant frequency (fr) are investigated. We propose a novel Dielectric-Embedded Piston Mode (DEPM) structure, achieved by partially etching a piezoelectric film filled with SiO2, which can almost suppress the transverse modes between the resonant frequency (fr) and anti-resonant frequency (fa) when applied on ZY-cut LiNbO3-based A1 mode resonators. This indicates that compared with Broadband Piston Mode (BPM), Filled-broadband Piston Mode (FPM) and standard structures, the DEPM structure is superior. Furthermore, the design parameters of the resonator are optimized by adjusting the width, depth and filled materials in the etched window of the DEPM structure to obtain a better suppression of transverse modes. The optimized A1 mode resonator using a DEPM structure exhibits a transverse-free response with a high fr of 3.22 GHz and a large K2 of ~30%, which promotes the application of A1 mode devices for use in 5G RF front-ends.

“…Surface acoustic wave (SAW) filters exhibit excellent frequency band selectivity and are small, serving as an irreplaceable component in the front-end radio frequencies (RF) required for modern communication [ 1 , 2 , 3 , 4 , 5 ]. To fulfill the explosive growth of data transmission demands and ubiquitous wireless connectivity in 5G communications, significantly wider bandwidths (BW) are required for 5G compared to previous generations of communication technologies [ 6 , 7 , 8 , 9 ].…”

Section: Introductionmentioning

confidence: 99%

Fractional Bandwidth up to 24% and Spurious Free SAW Filters on Bulk 15°YX-LiNbO3 Substrates Using Thickness-Modulated IDT Structures

et al. 2022

To cope with ubiquitous wireless connectivity and the increased and faster data delivery in 5G communication, surface acoustic wave (SAW) filters are progressively requiring wider bandwidths. Conventional bulk 15°YX-LiNbO3 substrates with a large coupling coefficient (K2) are attractive for the low-cost mass production of wideband SAW filters, but these generally suffer from spurious responses, limiting their practical application. In this work, a novel and simple SAW configuration is proposed that uses thickness-modulated interdigital transducer (IDT) structures to overcome the limitations set by spurious responses. Different from the conventional design where the thicknesses of the IDT electrodes in the series and parallel resonators generally kept the same, the proposed configuration adopts IDT electrodes of different thicknesses in the series and shunt resonators to suppress or remove unwanted spurious Rayleigh modes from the filter passband. Two different ultra-wideband SAW filter designs employing thickness-modulated IDTs were designed and fabricated to validate the effective suppression of spurious modes. The SAW filters experimentally featured spurious-free responses in the passband as well as a large 3 dB fractional bandwidth (FBW) in the 18.0% and 24.1% ranges and low insertion losses below 1 dB. This work can significantly broaden the range of applications for SAW devices and can open a pathway to commercialize ultra-wideband SAW filters in 5G communication systems.