Inter-digital transducer, surface acoustic wave filter and communication apparatus using the same
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsHiroyuki Nakamura, Toru Yamada, Kazunori Nishimura, Toshio Ishizaki, Narihiro Mita
Life of this patent
Estimating the term…
Abstract
An inter-digital transducer has a piezoelectric substrate; and an IDT (inter-digital transducer) electrode having a pair of upper bus bar electrode and lower bus bar electrode placed facing each other on the piezoelectric substrate and a plurality of electrode fingers placed on the piezoelectric substrate each being led out from either the upper bus bar electrode or the lower bus bar electrode toward the other bus bar electrode, wherein the IDT electrode is constructed of a plurality of divisional IDT electrodes and connected to a balanced type terminal.
Claims39
An inter-digital transducer comprising:
- a piezoelectric substrate;
- and
- an IDT (inter-digital transducer) electrode having a pair of upper bus bar electrode and lower bus bar electrode placed facing each other on said piezoelectric substrate and a plurality of electrode fingers placed on said piezoelectric substrate each being led out from either said upper bus bar electrode or said lower bus bar electrode toward the other bus bar electrode,
- wherein said IDT electrode is constructed of a plurality of divisional IDT electrodes and connected to a balanced type terminal,
- wherein said plurality of divisional IDT electrodes includes at least three divisional IDT electrodes, and
- wherein the ratio in the number of electrode fingers among said plurality of divisional IDT electrodes is adjusted beforehand so as to have a predetermined impedance value.
An inter-digital transducer comprising:
- a piezoelectric substrate;
- and
- an IDT (inter-digital transducer) electrode having a pair of upper bus bar electrode and lower bus bar electrode placed facing each other on said piezoelectric substrate and a plurality of electrode fingers placed on said piezoelectric substrate each being led out from either said upper bus bar electrode or said lower bus bar electrode toward the other bus bar electrode,
- wherein said IDT electrode is constructed of a plurality of divisional IDT electrodes and connected to a balanced type terminal,
- wherein at least two of said plurality of divisional IDT electrodes are equivalently connected in series and at least one of the remaining divisional IDT electrodes is connected in parallel with said at least two divisional IDT electrodes, and
- wherein the ratio in the number of electrode fingers among said plurality of divisional IDT electrodes is adjusted beforehand so as to have a predetermined impedance value.
Dependencies are inferred from the claim text.