Taiyo Yuden Co., Ltd.

Fujitsu Media Devices Limited

Noriaki Taniguchi

Osamu Kawachi

Osamu Furukawa

Toshio Nishizawa

Toshihiko Murata

A duplexer includes: a transmit filter connected between a transmit terminal and an antenna terminal and including series resonators and parallel resonators connected in a ladder form; and a receive filter connected between a receive terminal and the antenna terminal, wherein at least one of resonators, which are resonators other than a first series resonator and a first parallel resonator located at a first stage as viewed from a side of the transmit terminal and a second series resonator and a second parallel resonator located at a first stage as viewed from a side of the antenna terminal and have electrostatic capacitances less than an electrostatic capacitance of at least one of the first series resonator, the first parallel resonator, the second series resonator, and the second parallel resonator in the series resonators and the parallel resonators, is divided in series.

Duplexer

Provided is a duplexer that can maintain isolation characteristics while being able to independently adjust the input/output ground inductances and the common ground inductance of the double-mode filter. The duplexer includes: a transmitting filter; a receiving filter; a package substrate that includes a first substrate, a die attach layer that is patterned onto the first substrate, a second substrate, and an inner layer located between the first substrate and the second substrate; a double-mode filter that constitutes a portion of the receiving filter; a common ground terminal that makes an input ground and an output ground of the double-mode filter commonly grounded, the common ground terminal constituting a portion of the die attach layer; an input-side ground terminal of the double-mode filter, the input-side ground terminal constituting a portion of the inner layer; and an output-side ground terminal of the double-mode filter, the output-side ground terminal constituting a portion of the inner layer and being formed separately from the input-side ground terminal.

The present invention permits further miniaturization and shortening of a surface acoustic wave device while avoiding the influence of the surface acoustic wave device on the inductance value and performance index (Q value) of the spiral inductor. The chip on which the spiral inductor is formed is flip-chip mounted in a package together with another surface acoustic wave device chip. The package is provided with a hermetically sealed lid. A conductor pattern is formed on a face of the package that opposes the spiral inductor. Further, the overlap between the region of the spiral inductor and the conductor pattern is 7% or less.

Growing community of inventors

Kanagawa, Japan

Noriaki Taniguchi