Title:
PIEZOELECTRIC FILTER AND OUT-OF-BAND REJECTION IMPROVEMENT METHOD THEREFOR, MULTIPLEXER, AND COMMUNICATION DEVICE
Document Type and Number:
WIPO Patent Application WO/2021/208925
Kind Code:
A1
Abstract:
A method for improving out-of-band rejection of a piezoelectric filter. The piezoelectric filter has a ladder structure (100), and each step of the ladder structure (100) comprises a series resonator (110) and a parallel resonator (120). The method comprises: adjusting the thickness of one or more layers in the series resonator (110) and the parallel resonator (120) in the ladder structure (100) of at least one step, and/or, adjusting the materials of all the series resonators (110) and/or parallel resonators (120), so that an anti-resonance frequency corresponding to a high-order parasitic resonance of the parallel resonator (120) in the ladder structure (100) is higher than a resonance frequency corresponding to a high-order parasitic resonance of the series resonator (110), or a difference therebetween is less than a set value. By adjusting the thicknesses of the layers in the resonators (110, 120), the position of the high-order parasitic resonance of the parallel resonator (120) moves from a position much lower than the high-order parasitic resonance of the series resonator (110) to an equivalent or higher position, thereby suppressing or eliminating a pseudo-passband phenomenon in a high-order parasitic resonance region and thus improving the out-of-band suppression performance of the filter.
Inventors:
ZHENG YUNZHUO (CN)
PANG WEI (CN)
PANG WEI (CN)
Application Number:
PCT/CN2021/087003
Publication Date:
October 21, 2021
Filing Date:
April 13, 2021
Export Citation:
Assignee:
ROFS MICROSYSTEM TIANJIN CO LTD (CN)
International Classes:
H03H9/02; H03H9/205
Foreign References:
| CN111917392A | 2020-11-10 | |||
| CN106026961A | 2016-10-12 | |||
| CN110492864A | 2019-11-22 | |||
| CN109802644A | 2019-05-24 | |||
| CN110943711A | 2020-03-31 | |||
| CN102232270A | 2011-11-02 | |||
| CN107210731A | 2017-09-26 | |||
| US20120274416A1 | 2012-11-01 | |||
| US6025763A | 2000-02-15 |
Attorney, Agent or Firm:
CHINA SMART INTELLECTUAL PROPERTY LTD. (CN)
Download PDF: