BULK ACOUSTIC WAVE FILTER

摘要

PURPOSE: A bulk acoustic wave filter is provided to perform tuning of a resonator easily by a simple structure. CONSTITUTION: A substrate(2) has a number of space parts(4) on its upper surface and is almost flat. A number of resonators are constituted with an insulation thin film(6) and the first conduction layer(8) and a piezoelectric layer and the second conduction layer(12) formed on each space part. And a tuning layer(14) is on the second conductive layer of the selected resonator to tune a resonant frequency of the selected resonator. The tuning layer is one of SiO2 or Si3N4.