THIN FILM BULK ACOUSTIC RESONATOR

摘要

Provided is a thin film bulk acoustic resonator by which resonance characteristics can be improved by suppressing generation of standing waves due to acoustic waves in lateral mode to the minimum. The thin film bulk acoustic resonator is provided with a resonating section (A) wherein a piezoelectric layer (3) is sandwiched between a first electrode (2) and a second electrode (4). In the resonator, the resonating section (A) has an ellipsoidal planar shape having a portion cut by a straight line (L). The straight line (L) crosses at last the short axis or the long axis of the ellipse, preferably the both, and passes the center of the ellipse.