Longitudinally coupled multi-mode piezoelectric bulk wave filter and electronic components using the same

A longitudinally coupled multi-mode piezoelectric bulk wave filter, using a piezoelectric longitudinal effect, comprising:

• at least one laminated piezoelectric element including:
• at least four excitation electrodes disposed substantially parallel to and spaced from one another at a distance D;
• and
• a plurality of piezoelectric layers, each disposed between two adjacent electrodes of said at least four excitation electrodes, the plurality of piezoelectric layers being polarized in a direction that is substantially perpendicular or parallel to said at least four excitation electrodes, wherein a cross section of said at least one laminated piezoelectric element in the direction that is substantially perpendicular to a lamination direction of said at least one laminated piezoelectric element is substantially rectangular and has a thickness T;
• a piezoelectric portion having a thickness that is greater than the thickness dimension T and being aligned with said at least one laminated piezoelectric element;
• an input electrode;
• an output electrode;
• a ground electrode;
• said at least four excitation electrodes including:
• a first group of excitation electrodes electrically connected to the input electrode;
• a second group of excitation electrodes electrically connected to the output electrode;
• and
• a third group of excitation electrodes electrically connected to the ground electrode, the first group and the third group being alternately disposed in the lamination direction, and the second group and the third group being alternately disposed in the lamination direction;
• wherein
• when an input signal is applied between the input electrode and the ground electrode, mode vibrations having different orders are generated and combined into an output signal between the output electrode and the ground electrode, and the ratio of the thickness T to the distance D is equal to or less than about 0.9.