Balanced filter structure utilizing bulk acoustic wave resonators having different areas
First Claim
1. A filter structure having a first signal line, a second signal line, a third signal line, and a fourth signal line, characterized in that the structure comprisesa first bulk acoustic wave resonator having substantially a first area, a second bulk acoustic wave resonator having substantially a first area, a third bulk acoustic wave resonator having substantially a second area, and a fourth bulk acoustic wave resonator having substantially a second area, and in that said first bulk acoustic wave resonator is connected between the first signal line and the third signal line, said second bulk acoustic wave resonator is connected between the second signal line and the fourth signal line, said third bulk acoustic wave resonator is connected between the first signal line and the fourth signal line, and said fourth bulk acoustic wave resonator is connected between the second signal line and the third signal line, and in that said first area is substantially different from said second area.
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Accused Products
Abstract
The invention relates to resonator structures of radio communication apparatus, especially bulk acoustic wave filter structures. According to the invention, a bulk acoustic filter structure is constructed with a lattice configuration, in which two of the filters have a different area than other two for creating very steep passband edges in the frequency response of the filter. Preferably, the filter structure further comprises a second lattice structure for increasing the stopband rejection ratio of the filter structure, and for allowing the use of a simple mechanical structure. The cascaded configuration allows the construction of the filter structure in such a way, that the electrodes of the input and output port are at the same layer, thereby removing the need to make vias in the piezoelectric layer, which results in considerable simplification of the manufacturing process. Preferably, an acoustical mirror structure is used as the acoustical isolation in order to further simplify the mechanical structure of the filter structure.
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Citations
10 Claims
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1. A filter structure having a first signal line, a second signal line, a third signal line, and a fourth signal line, characterized in that the structure comprises
a first bulk acoustic wave resonator having substantially a first area, a second bulk acoustic wave resonator having substantially a first area, a third bulk acoustic wave resonator having substantially a second area, and a fourth bulk acoustic wave resonator having substantially a second area, and in that said first bulk acoustic wave resonator is connected between the first signal line and the third signal line, said second bulk acoustic wave resonator is connected between the second signal line and the fourth signal line, said third bulk acoustic wave resonator is connected between the first signal line and the fourth signal line, and said fourth bulk acoustic wave resonator is connected between the second signal line and the third signal line, and in that said first area is substantially different from said second area.
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10. Mobile communication means comprising a filter having a first signal line, a second signal line, a third signal line, and a fourth signal line, characterized in that the filter further comprises
a first bulk acoustic wave resonator having substantially a first area, a second bulk acoustic wave resonator having substantially a first area, a third bulk acoustic wave resonator having substantially a second area, and a fourth bulk acoustic wave resonator having substantially a second area, and in that said first bulk acoustic wave resonator is connected between the first signal line and the third signal line, said second bulk acoustic wave resonator is connected between the second signal line and the fourth signal line, said third bulk acoustic wave resonator is connected between the first signal line and the fourth signal line, and said fourth bulk acoustic wave resonator is connected between the second signal line and the third signal line, and in that said first area is substantially different from said second area.
Specification
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- Resources
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Current AssigneeNokia Technologies Oy (Nokia Corporation)
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Original AssigneeNokia Mobile Phones UK Limited (Nokia Corporation)
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InventorsEllä, Juha
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Primary Examiner(s)Lee, Benny
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Assistant Examiner(s)Summons, Barbara
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Application NumberUS09/473,395Time in Patent Office602 DaysField of Search333/187-192, 310/312, 310/311, 310/320, 310/321, 310/324, 310/366US Class Current333/189CPC Class CodesH03H 9/568 consisting of a ladder conf...
