| 摘要 |
PURPOSE:To improve the accuracy of a filter, by providing an auxiliary electrode between plural number of energy enclosure type resonators respectively and eliminating the frequency dependancey of a transfer conductance of an imaginary jyrator of the coupling section between the resonators. CONSTITUTION:The energy enclosure type resonators 6, 6 are provided on a piezoelectric substrate 5 and the auxiliary electrode 7 is provided between the resonators 6, 6 respectively. Further, the ratio d/b of the distance (d) between the resonators 6, 6 and the auxiliary electrode 7 to the width (b) of the electrode 7 is set to a value depending on the resonance frequency of the resonators. Thus, the transfer conductance of the coupling imaginary jyrator between the resonators is constant to the frequency and the frequency dependancy is eliminated. Thus, the accuracy of the filter is improved. |
