Method of Reducing In-band Fluctuation of Large Broadband Low Loss Ladder SAW Filter

A sound surface filter, low-loss technology, applied in the field of reducing the in-band fluctuation of large-bandwidth and low-loss trapezoidal sound surface filters, can solve problems such as difficult engineering applications, photoresist corrosion, etc., and achieve high adhesion, Excellent mechanics, the effect of meeting high reliability requirements

Active Publication Date: 2018-07-10
北京中科飞鸿科技股份有限公司
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Problems solved by technology

Some scholars in the world use the trapezoidal design method combined with Y15-LiNbO3 material and Cu film technology to prepare large bandwidth and low loss devices. The relative bandwidth can reach 19%, and the loss is about 0.61dB. Scattered signals form a spurious response in the band, resulting in an in-band fluctuation of about 8dB. The in-band fluctuation is reduced to About 4dB, but the photoresist is corrosive, and the product is difficult to realize engineering application
[0004] In addition, there are no other effective methods at home and abroad to suppress the resonance of the transverse mode and the Rayleigh wave of the parallel arm. fluctuations, to ensure that the device meets the requirements of use

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[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0032] In the embodiment of the present invention, by suppressing the in-band parasitic response caused by the parallel arm Rayleigh wave, thereby reducing the 15°YX-LiNbO 3 In-band ripple of wide bandwidth and low loss ladder-shaped surface acoustic filter prepared by depositing copper film on substrate. The photoresist-type polyimide resin material of the embodiment of the present invention replaces the traditional photoresist and sound-absorbing...

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Abstract

The invention discloses a method for reducing in-band fluctuations of a large-broadband low-loss trapezoidal surface acoustic wave filter. The method comprises the following steps: preparing a trapezoidal surface acoustic wave filter by precipitating a copper film on 15-DEG C YX-LiNbO3 substrate; and selecting a photoetching type polyimide resin, by use of an overlay technology, coating the surface of a trapezoidal surface acoustic wave filter parallel resonator with the photoetching type polyimide resin, and carrying out high-temperature imidization processing so as to form a polyimide film on the surface of the trapezoidal surface acoustic wave filter parallel resonator. The method disclosed by the invention can effectively inhibit an in-band parasitic effect and reduces the in-band fluctuations.

Description

technical field [0001] The invention relates to the technical field of SAW filters, in particular to a method for reducing in-band fluctuations of a large-bandwidth and low-loss ladder-shaped SAW filter. Background technique [0002] As people's demand for informatization is getting higher and higher, high-speed and large-capacity become a development direction for future information exchange. In order to meet this development requirement, the surface acoustic wave filter, one of the key components in the communication field, must Development in the direction of bandwidth, low loss, high rectangularity, and miniaturization. [0003] The conventional SAW filter substrate material that realizes large bandwidth and low loss is 41°LiNbO3, and its electromechanical coupling coefficient is about 17%. The maximum 3dB relative bandwidth can be 7% to 8%, and the loss is about 4dB. As for 15oYX-LiNbO3 material, its electromechanical coupling coefficient reaches 25%-30%, the maximum 3...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03H9/02H03H9/64H03H3/08
CPCH03H3/08H03H9/02818H03H9/6483
Inventor 闫坤坤黄歆杨丽萍刘璐杨思川
Owner 北京中科飞鸿科技股份有限公司
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