Resonator and trapezoidal filter

Abstract

The invention relates to the field of communication, and provides a resonator and a trapezoidal filter. The resonator comprises a substrate, a bottom electrode, a piezoelectric layer, a top electrode,a sound wave reflection structure and a protrusion structure used for adjusting the passband performance of the filter. The piezoelectric layer is located between the top electrode and the bottom electrode, and the protruding structure is located on the surface, away from the piezoelectric layer, of the top electrode, or located on the surface, below the top electrode, of the piezoelectric layer,or located on the upper surface, below the piezoelectric layer, of the bottom electrode, or located below the bottom electrode. The acoustic reflection structure is located between the substrate andthe bottom electrode. Compared with the prior art, the method is simple, the left clutter in the impedance frequency characteristic curve of the series resonator is moved leftwards through the convexstructure design, so that the defects in the passband of the filter are moved into the stop band of the filter, thereby improving the performance of the filter, and the piezoelectric layer is doped with rare earth elements, so that the reduction of the electromechanical coupling coefficient of the resonator caused by the convex structure design can be made up.

Description

technical field [0001] The invention relates to the technical field of communication, in particular to a resonator and a ladder filter. Background technique [0002] With the rapid development of wireless communication systems, people put forward new requirements such as miniaturization, integration, and high frequency for filter devices of wireless terminals. Film Bulk Acoustic Resonator (FBAR for short), because of its high resonance frequency, high quality factor, high power capacity, low power consumption, low price and many other advantages, can be cascaded to form a high operating frequency, low insertion loss, high Filters and duplexers with steep drop characteristics and high power tolerance are generally considered to be the best solution to replace surface acoustic wave devices to solve duplexers in high-density frequency bands for wireless communications, and have attracted widespread attention. [0003] A typical FBAR structure such as figure 1 As shown, it inc...

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Problems solved by technology

[0005] However, if image 3 As shown, the added raised structure will cause the series resonator to have spurious peaks 301 on the left side of the impedance frequency curve, resulting in defects 302 in the passband of the filter, thereby degrading the performance of the filter

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