Patent ID: 7561010
Filing Date: 2009-07-14
Classification: H03H

Abstract:
1. A piezoelectric thin film resonator comprising: a first piezoelectric thin film; a second piezoelectric thin film formed on an upper surface of the first piezoelectric thin film; a first electrode formed on a lower surface of the first piezoelectric thin film; a second electrode formed between the first and second piezoelectric thin films; and a third electrode formed on an upper surface of the second piezoelectric thin film; wherein said second electrode is bisected and a high frequency voltage is applied between one electrode and the other electrode, and wherein said first and said third electrode are floating electrodes with no electric supply, thereby causing the direction of the electric field in the first piezoelectric thin film which is located under said one electrode and the direction of the electric field in the second piezoelectric thin film which is located above said one electrode mutually to become opposite and periodically inverted, and thereby causing the direction of the electric field in the first piezoelectric thin film which is located under said the other electrode and the direction of the electric field in the second piezoelectric thin film which is located above said the other electrode mutually to become opposite and periodically inverted, and wherein the displacement component perpendicular to the plane of all the first and second piezoelectric thin films is predominant for the displacement of oscillation in the first and second piezoelectric thin films at the resonance frequency, and the direction of the displacement perpendicular to the plane is reversed at the center of the cross section perpendicular to the plane.