Patent ID: 7187255
Filing Date: 2007-03-06
Classification: H03H

Abstract:
1. A filter, comprising: a first stage having a plurality of resonators disposed on a substrate, each resonator comprising a first electrode and a second electrode disposed vertically adjacent such that an acoustic cavity of a piezoelectric material is formed between each first electrode and each second electrode of each resonator, the first and second electrodes of each resonator electrically isolated from each other via the piezoelectric material; a balanced first stage input having a first input terminal and a second input terminal, the first input terminal connected to the first electrode of a first resonator and the second input terminal connected to the first electrode of a second resonator; a balanced first stage output having a first output terminal and a second output terminal, the first output terminal connected to the second electrode of the first resonator and the second output terminal connected to the second electrode of a third resonator; a second stage connected to the first stage; the second stage having a balanced second stage input having a first input terminal and a second input terminal, the first input terminal connected to the first electrode of a fifth resonator and the first output terminal of the balanced output of the first stage and the second input terminal connected to the first electrode of a sixth resonator and the second output terminal of the balanced output of the first stage; and a balanced second stage output having a first output terminal and a second output terminal, the first output terminal connected to the second electrode of the fifth resonator and the second output terminal connected to the second electrode of a seventh resonator; wherein each resonator is disposed such that at least two resonators of the first stage are adjacent to at least two resonators of the second stage, each resonator is substantially trapezoidal in the plane of the substrate, and each resonator is disposed on the substrate adjacent to at least two other resonators such that at least two sides of every resonator are parallel with at least one side of an adjacent resonator.