Patent ID: 7248132
Filing Date: 2007-07-24
Classification: H03H

Abstract:
1. A method of filtering, comprising a first signal line, a second signal line, a third signal line and a fourth signal line, said first and third signal lines defining an input port and said second and fourth signal lines defining an output port of a section of said filter structure, said section being defined by a first bulk acoustic wave resonator (A) which is connected between said first signal line and said second signal line, a second bulk acoustic wave resonator (G) which is connected between said third signal line and said fourth signal line, a third bulk acoustic wave resonator (C) which is connected between said first signal line and said fourth signal line, and a fourth bulk acoustic wave resonator (F,) which is connected between said second signal line and said third signal line; wherein at least one further section of first, second, third and fourth bulk acoustic wave resonators (B, H, F, D) is provided, wherein the input port of each said further section is connected with the output port of a preceding section to form a multiple-section filter structure, characterized in that a frequency pulling factor defined δ of at least one of said acoustic wave resonators is non-zero, for third and fourth bulk acoustic wave resonators having an anti-resonant frequency fo