高阻带抑制FBAR滤波器

FBAR Filter with High Stopband Suppression

摘要:

采用一维Mason模型,研究了薄膜体声波谐振器(FBAR)压电层/电极膜厚比对有效机电耦合系数的影响。随着压电层膜厚占比的增加,谐振器有效机电耦合系数逐渐增大,通过膜厚优化和流片实现了高频FBAR 谐振器的研制。在采用梯形电路结构的基础上,研究了滤波器级数、串并联谐振器静态电容比、并联谐振器串联电感对滤波器阻带抑制的影响,通过工艺流片,制备了一款中心频率为4.4 GHz、通带最低损耗为2.3 dB、-1 dB带宽为112 MHz、通带两侧带外抑制优于50 dBc的FBAR滤波器芯片,为高频高抑制FBAR滤波器的研制提供了参考。

Abstract:

A one-dimensional Mason model was used to study the effect of the piezoelectric layer and electrode thickness ratio on the effective electromechanical coupling coefficients of FBAR resonators. As the proportion of pie zoelectric layer thickness increases, the effective electromechanical coupling coefficient of the resonator gradually in creases. A high-frequency FBAR resonator was developed via film thickness optimization and chip fabrication. Based on adopting trapezoidal circuit structures, the effects of the stages of the filter, ratio of static capacitance in series and parallel resonators, and series inductance of parallel resonators on the suppression of filter stopband were studied. Through chip fabrication, an FBAR filter chip with a center frequency of 4.4 GHz, minimum passband loss of 2.3 dB, -1 dB bandwidth of 112 MHz, and near end out of band suppression of better than 50 dBc on both sides of the passband was prepared, thus providing a reference for the development of high-frequency and high-sup pression FBAR filters.