Duplexer

Abstract

The invention relates to the technology of radio frequency filters and duplexers, in particular to a duplexer, which comprises a base substrate, and a receiving end filter and a transmitting end filter which are positioned on the base substrate and have different frequency bands; the receiving end filter and the transmitting end filter each comprise a plurality of stacked bulk acoustic wave resonators; each stacked bulk acoustic wave resonator comprises a substrate, an acoustic reflection layer, a bottom electrode, a plurality of piezoelectric material layers, a plurality of middle electrode layers and a top electrode. According to the stacked bulk acoustic wave resonator, a multi-layer piezoelectric oscillation pile series structure is formed by the piezoelectric material layers and the electrode layers, the resonant frequency of the resonator can be improved, the resonant frequency of a single resonator is modulated by adjusting the number of stacked layers of the stacked bulk acoustic wave resonator, and the resonant frequencies of the resonators of the receiving filter and the transmitting filter are matched, so that the integration of the duplexer is realized.

Description

technical field [0001] The invention belongs to the technical field of radio frequency filters and duplexers, in particular to a duplexer. Background technique [0002] In mobile communication devices, filters are the core components that can communicate. With the advent of the 5G era, the mobile communication field is constantly developing towards the goal of higher frequency and wider frequency band, and the development trend of smart communication equipment is miniaturization and thinning. However, as the frequency band of data communication and transmission is getting higher and higher, the frequency range covered by mobile communication is getting larger and larger, which means that more and more filters are needed to realize data selection and transmission to achieve full-band communication Requirements hinder the miniaturization of mobile communication devices. The purpose of a duplexer is to separate the modulated transmit and receive signals at the antenna of a ce...

AI Technical Summary

Problems solved by technology

However, with the continuous improvement of communication frequency, the center frequency of SAW filter can only reach about 2GHz due to the limitation of its own structure and the nature of surface acoustic wave, which cannot meet the requirements of 5G communication frequency.

The resonance frequency of the bulk acoustic wave is determined by the thickness of the piezoelectric layer. The center frequency of the FBAR filter can reach the 5G frequency band, but while satisfying the ultra-high frequency band above 5G or even 6G, the piezoelectric film layer itself is reduced to hundreds or even tens of Nano, which will inevitably cause film defects to seriously reduce the performance of piezoelectric materials, bring pseudo modes and other parasitic modes, reduce device performance, and greatly increase the difficulty of the process

[0004] The traditional bulk acoustic wave resonator increases the frequency of the resonator by reducing the thickness of the piezoelectric material layer and the electrode, but when the material is too thin, it will increase the difficulty of the processing process and bring defects to reduce the performance of the piezoelectric material, resulting in false mode and parasitic mode

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