An acoustic wave filter, a method of improving performance, a multiplexer and a communication device

By introducing passive coupling elements into the series and parallel branches of the filter, the problem of insufficient out-of-band rejection and roll-off performance of traditional filters is solved, and the out-of-band rejection and roll-off performance of the filter is improved without increasing the in-band insertion loss and size.

CN115833784BActive Publication Date: 2026-07-17ROFS MICROSYST TIANJIN CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
ROFS MICROSYST TIANJIN CO LTD
Filing Date
2021-09-16
Publication Date
2026-07-17

AI Technical Summary

Technical Problem

While traditional filters increase out-of-band rejection and roll-off, they also lead to increased in-band insertion loss and larger filter size. Existing methods cannot effectively improve roll-off performance.

Method used

Multiple series resonators are connected in series on the series branch of the filter, and new passive coupling elements are set on the parallel branch. By introducing uncoupled elements, including combinations of capacitors, inductors and resonators, on the parallel branch, passive coupling elements are set on the connection nodes between the inductors and resonators, and on the connection nodes between the inductors and resonators, respectively, to improve out-of-band rejection performance.

Benefits of technology

Without increasing the filter order or in-band insertion loss, it significantly improves out-of-band rejection and roll-off performance, and optimizes the filter structure design.

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Abstract

The embodiment of the present application discloses a kind of acoustic wave filters, multiple series resonators are on series branch, and parallel branch is connected between two adjacent series resonators, and parallel branch includes at least one parallel resonator and at least one ground inductance, the filter further includes: at least one parallel branch group, it is connected between two specified series resonators, and it is made of first parallel branch and second parallel branch, at least one passive coupling element, one end is connected on the connecting node between the parallel resonator and ground inductance of one parallel branch in parallel branch group, the other end is connected on the connecting node between the parallel resonator and ground inductance of another parallel branch in parallel branch group or any one connecting node except the connecting node of series branch where parallel branch group is located.The embodiment of the present application also discloses a kind of method for improving the performance of acoustic wave filter, multiplexer and communication equipment.The present application improves out-of-band rejection and improves roll-off without deteriorating in-band insertion loss.
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