The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 01, 2002
Filed:
Apr. 13, 2000
Seiko Epson Corporation, Tokyo, JP;
Abstract
A multi-longitudinal-mode-coupled resonator type SAW filter having flat passband characteristic is provided. In the multi-longitudinal-mode-coupled resonator type SAW filter, an energy trapped type SAW resonator is formed on a frequency upward type piezoelectric substrate, and an IDT is divided into three IDTs, a first IDT arranged to a transmitter side, a second IDT arranged to a receiver side, and a third IDT arranged between the first IDT and the second IDT to control the amplitude of the vibration displacement in two modes for forming a filter. A frequency potential is optimized by changing an electrode period length of each IDT. Resonance amplitude strengths in the two modes are thus equalized and passband transmission characteristics are thus flattened. A filter having a relatively wide bandwidth of 1000 to 1500 ppm is fabricated by using a substrate having a small electromechanical coupling factor, such as a quartz crystal substrate.