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:
Oct. 29, 2002
Filed:
Mar. 07, 2000
Nortel Networks Limited, St. Laurent, CA;
Abstract
A filter comprises a shallow bulk acoustic wave (SBAW) longitudinally coupled double mode resonator (LCR) and a reactance coupled between an input and an output of the resonator. Due to its use of a piezoelectric substrate with high electromechanical coupling and an orientation for propagating SBAWs, the resonator has a relatively poor stop band attenuation in a shoulder region on a high frequency side of its pass band. At frequencies in the shoulder region, a signal coupled via the resonator from the input to the output is reduced by a signal of opposite phase coupled via the reactance with a similar attenuation, thereby improving attenuation in the shoulder region. The reactance can be a capacitance formed on the substrate surface.