Surface acoustic wave element and duplexer having the same
AssigneeFujitsu Media Devices Limited
InventorsJun Tsutsumi, Masahiko Imai, Shogo Inoue, Takashi Matsuda
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Abstract
A surface acoustic wave element includes surface acoustic wave (SAW) resonators arranged in a ladder formation on a piezoelectric substrate. A resonance frequency fS1 of a series-arm resonator of a first stage viewed from an input side of the surface acoustic wave element and an average resonance frequency fSav of all of remaining series-arm SAW resonators satisfy 1.00fSav>fS1≧0.99fSav.
Claims22
A surface acoustic wave element comprising surface acoustic wave (SAW) resonators arranged in a ladder formation on a piezoelectric substrate,
- a resonance frequency fS1 of a series-arm resonator of a first stage viewed from an input side of the surface acoustic wave element and an average resonance frequency fSav of all of remaining series-arm SAW resonators satisfying 1.00fSav>fS1≧0.99fSav.
A surface acoustic wave element comprising surface acoustic wave (SAW) resonators arranged in a ladder formation on a piezoelectric substrate,
- ratios (electrode finger width)/(electrode finger period) in interdigital transducers of series-arm resonators are substantially equal to each other,
- a resonance finger period λS1 of the series-arm resonator of a first stage viewed from an input side of the surface acoustic wave element and an average electrode finger period λSav of all the remaining series-arm SAW resonators satisfying 1.01λSav≧λS1>1.00λSav.
A surface acoustic wave element comprising surface acoustic wave (SAW) resonators arranged in a ladder formation on a piezoelectric substrate,
- a resonance frequency fP1 of a parallel-arm resonator of a first stage viewed from an input side of the surface acoustic wave element and an average resonance frequency fPav of all of remaining parallel-arm SAW resonators satisfying 1.01fPav≧fP1>1.00fPav.
A surface acoustic wave element comprising surface acoustic wave (SAW) resonators arranged in a ladder formation on a piezoelectric substrate,
- ratios (electrode finger width)/(electrode finger period) in interdigital transducers of parallel-arm resonators are substantially equal to each other,
- a resonance finger period λP1 of the parallel-arm resonator of a first stage viewed from an input side of the surface acoustic wave element and an average electrode finger period λPav of all the remaining parallel-arm SAW resonators satisfying 1.00λPav>λP1≧0.99λPav.
Dependencies are inferred from the claim text.