Band-pass filter using film bulk acoustic resonator
AssigneeUbe Industries, Ltd.
InventorsKosuke Nishimura, Masataka Fujinaga, Masahide Kondo
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Abstract
A band-pass filter has a ladder-type circuit including first and second terminals whose characteristic impedances are Z0, and series elements and shunt elements disposed between a first terminal and a second terminal, each of the series elements and shunt elements containing a film bulk acoustic resonator. Assuming that characteristic impedance of any one of the series elements is Z1 and that characteristic impedance of any one of the shunt elements is Z2, the characteristic impedances Z0, Z1, and Z2 have a relation of 1<(Z1/Z0)<2, preferably 1.3<(Z1/Z0)<1.7, and 0.5<(Z2/Z0)<1, preferably 0.6<(Z2/Z0)<0.8.
Claims3
A band-pass filter having a ladder-type circuit including first and second terminals whose characteristic impedances are Z0, and series elements and shunt elements disposed between a first terminal and a second terminal, each of the series elements and shunt elements containing a film bulk acoustic resonator, wherein assuming that characteristic impedance of any one of the series elements is Z1 and that characteristic impedance of any one of the shunt elements is Z2, the characteristic impedances Z0, Z1, and Z2 have a relation of 1<(Z1/Z0)<2 and 0.5<(Z2/Z0)<1.
Dependencies are inferred from the claim text.