Fujitsu Media Devices Limited

Fujitsu Media Devices Limted

Hiroyuki Furusato

Osamu Kawachi

Masanori Ueda

Kiyohide Misawa

Toshio Nishizawa

Osamu Kawauchi

A SAW filter includes multiple SAW resonators. The multiple SAW resonators, which are connected in series, are connected any one of between a signal input terminal and a ground that is the closest thereto and between a signal output terminal and another ground that is the closest thereto. The SAW resonators have substantially equal electrostatic capacitances. It is thus possible to protect the SAW resonators without providing a sacrificial electrode for electrostatic breakdown, and thereby possible to configure the SAW filter having a high reliability against the electrostatic discharge.

Surface acoustic wave filter

Surface acoustic wave (SAW) filter includes SAW resonators, a discharge induction pattern is provided between a ground and at least one of a signal input terminal and a signal output terminal, and the discharge induction pattern has multiple gaps that are narrower than gaps that exist inside electrode patterns of the SAW resonators. Since the discharge induction pattern has multiple gaps that are narrower than gaps that exist inside electrode patterns of the SAW resonators, it is possible to induce the electrostatic discharge without fault. The multiple gaps are provided so as to protect the SAW resonators against multiple times of electrostatic discharge.

A surface acoustic wave device includes a package having a coefficient of linear expansion; and a piezoelectric element forming a surface acoustic wave element, and mounted on the package by a flip chip bonding. The piezoelectric element has different coefficients of linear expansion in a direction of propagation of surface acoustic waves generated by an interdigital electrode of the surface acoustic wave element and in a vertical direction thereto, and further has a long side existing to a direction having a coefficient of linear expansion close to the coefficient of linear expansion of the package. The piezoelectric element is cut out from a single crystal having X, Y, and Z crystal axes, and the X crystal axis agrees with a direction of propagation of the surface acoustic wave.

Surface acoustic wave device, communication device using the same, and antenna duplexer

A SAW device includes a piezoelectric substrate and a package body holding the piezoelectric substrate, wherein the package body includes a bottom part carrying the piezoelectric substrate in a face-down state and a side wall part laterally surrounding the piezoelectric substrate, the bottom part carrying a wiring pattern for electrical connection with an electrode pattern on the piezoelectric substrate, the wiring pattern including a first ground pattern and a second ground pattern in a mutually separated relationship, the first ground pattern and the second ground pattern being connected electrically with each other.

Growing community of inventors

Yokohama, Japan

Hiroyuki Furusato