Patent ID: 6115592
Filing Date: 2000-09-05
Classification: H01L,H03H,H04B

Abstract:
A filter device comprising:a package;at least two filter elements, provided in said package, each of said at least two filter elements passing only signals within a predetermined radio frequency band used by a radio signal portion of a dual-band radio system, said predetermined radio frequency bands of said at least two filter elements having center frequencies which are distinct from each other;an input terminal connected to and shared by respective inputs of said at least two filter elements;an output terminal connected to and shared by respective outputs of said at least two filter elements;a first phase matching unit provided between the input terminal and the inputs of said at least two filter elements, wherein said first phase matching unit comprises a first transmission line connected to the input terminal and connected to one of said at least two filter elements, a first inductor, and a first capacitor, said first inductor and said first capacitor being connected to the input terminal and connected to another one of said at least two filter elements; anda second phase matching unit provided between the output terminal and the outputs of said at least two filter elements, wherein said second phase matching unit comprises a second transmission line connected to the output terminal and connected to said one of said at least two filter elements, a second inductor, and a second capacitor, said second inductor and said second capacitor being connected to the output terminal and connected to said another one of said at least two filter elements,wherein said at least two filter elements include surface acoustic wave filter elements each of which passes only the signals within the predetermined radio frequency band;wherein said first and second phase matching units rotate a phase of the frequency passband for impedance matching with respect to said at least two filter elements;wherein said at least two filter elements, said first phase matching unit, and said second phase matching unit are packaged on a surface of said package;wherein said package comprises a cap which hermetically seals said at least two filter elements in said package;wherein said package has a leadless-chip-carrier structure, said at least two filter elements being packaged on a first surface of said package, and at least one of the first phase matching unit and the second phase matching unit being packaged on a second, opposite surface of said package;wherein said first phase matching unit comprises a first transmission line connected to the input terminal and connected to one of said at least two filter elements, and said second phase matching unit comprises a second transmission line connected to the output terminal and connected to said one of said at least two filter elements; andwherein said at least two filter elements and said at least one of the first phase matching unit and the second phase matching unit are eclectically connected to each other via said first and said second transmission lines.