A surface acoustic wave filter with an over-compensated interdigital structure

Abstract

The invention discloses a surface acoustic wave filter with an interdigital structure over-compensation function, and belongs to the field of filters. The surface acoustic wave filter comprises a piezoelectric substrate, an input interdigital transducer and an output interdigital transducer, wherein the input interdigital transducer and the output interdigital transducer are arranged on the piezoelectric substrate; In the input interdigital transducer and the output interdigital transducer, two square blocks are additionally arranged at the tail end of each interdigital electrode, so that thetail end of each interdigital electrode is T-shaped; Wherein the side length of the square block is greater than the light source wavelength of the selected photoetching machine, and the gap between each interdigital electrode and the adjacent square block is greater than the light source wavelength of the selected photoetching machine; The problem that the insertion loss and the relative bandwidth of a surface acoustic wave filter in the existing manufacturing process are not easy to meet the requirement of a device with higher type energy is solved. On the premise of not changing the designstructure, process and packaging of the surface acoustic wave filter, the effects of reducing the insertion loss, improving the relative bandwidth and improving the rectangularity are achieved.

Description

technical field [0001] The embodiments of the present invention relate to the field of filters, in particular to a surface acoustic wave filter with interdigital structure overcompensation. Background technique [0002] A surface acoustic wave is an elastic wave that propagates along the surface of an object. Surface acoustic wave devices have the characteristics of low cost, small size and multiple functions, and have been widely used in radar, communication, navigation, identification and other fields. With the continuous rapid development of mobile communication technology, it is an inevitable trend for surface acoustic wave filters to have more superior performance, ultra-low insertion loss, smaller package size, and high power resistance. [0003] Conventional substrate materials for surface acoustic wave filters include piezoelectric film materials such as quartz, lithium tantalate, and barium niobate. The interdigital transducer is printed on the surface of the piezo...

AI Technical Summary

Problems solved by technology

At present, the surface acoustic wave filter on the market is limited by factors such as the electromechanical coupling coefficient of the material, the design scheme, and the process. The bandwidth of the surface acoustic wave filter is generally below 5% of the center frequency, and the insertion loss in the passband is above 1db. And the squareness relative to the bandwidth isn't particularly good either.

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