Abstract
Radio frequency (RF) filters with multiple passbands can meet the needs of miniaturization and integration for 5G communications. This paper reports a dual-mode Lamb wave resonator (DLWR) and a dual-passband filter based on DLWRs. The DLWR consists of a piezoelectric film and two interdigital electrode (IDT) arrays with different thicknesses, which leads to the coexistence of two main modes in the resonator. The resonance frequencies of the two modes can be adjusted separately by changing the thicknesses of the IDTs, which greatly satisfies the requirements of the dual-passband filter. Four DLWRs with different electrode configurations are designed, and the influences of the periodic length and thicknesses of the IDTs on the performance of the DLWR are studied. When the thickness of the piezoelectric layer is 0.75 μm and the two thicknesses of the IDTs are 0.1 μm and 0.3 μm, the resonance frequency of the second main mode is 1.27 GHz higher than the resonance frequency of the first main mode in the DLWR. Furthermore, a dual-passband filter based on the proposed DLWRs is demonstrated with an insertion loss less than 1 dB and a band rejection of about 15 dB. Moreover, two passbands at 2.45 GHz and 3.88 GHz with bandwidths of 66 MHz and 112 MHz, respectively, are achieved. The presented DLWR shows a potential application that can be used to obtain RF filters with adjustable dual passbands.
Highlights
IntroductionA highly integrated radio frequency (RF) front-end module is in demand with the rapid commercialization of fifth generation (5G) technology [1–4]
Academic Editor: Niall TaitA highly integrated radio frequency (RF) front-end module is in demand with the rapid commercialization of fifth generation (5G) technology [1–4]
The bandwidth of the filter is closely related to the Ke2f f of the resonator, so it is very important to study the influence of pitch on the Ke2f f of resonators [34]
Summary
A highly integrated radio frequency (RF) front-end module is in demand with the rapid commercialization of fifth generation (5G) technology [1–4]. RF filters based on piezoelectric resonators play an important role in the front-end module. The requirements of miniaturization and integration in filters are desired to achieve low-energy consumption and a light weight. Reducing the area of resonators is a choice, but the small active area may affect the performance of the resonator. A multi-passband filter based on multi-mode resonators can realize the function that needs multiple single-passband filters. Integrating multiple passbands into a filter is an effective method to reduce the dimension and number of electronic devices in the RF front-end module without sacrificing the performance of the filters [6]. Dual-mode resonators have important applications in sensors [7] and other fields [8,9]
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