Transversally coupled resonator filter

US6762534B2 · kind B2 · utility

Assignee

• Tele Filter Zweigniederlassung der Dover Germany, GmbH · DE

Inventors

• Günter Martin · Dresden, DE
• Bert Wall · Potsdam, DE

Key dates

• Filing date: Aug 6, 2002
• Grant date: Jul 13, 2004
• Expiry date: Jan 23, 2023

Classification

• Technology area (CPC H): Electricity
• CPC primary: H03H9/6463
• WIPO field: Basic communication processes
• WIPO sector: Electrical engineering

Abstract

The invention relates to a transverse-mode-coupled resonator filter based on surface acoustic waves.The object of the invention is to modify such resonator filters, in which there are disposed adjacent to one another on a substrate (1) a plurality of one-port resonator structures (2; 3), which comprise two strip reflectors (22 and 23; 32 and 33) and an interdigital transducer (21; 31) and together form a waveguide for surface acoustic waves, in such a way that the insertion loss of the filters is reduced, especially by reducing the damping due to the cascade connection.This object is achieved by the fact that at least one of the one-port resonator structures (2; 3) differs from the other one-port resonator structures by the ratio of the finger width to the spacing (216) of the finger centers (214; 215) and by the ratio of the width of the reflector strips (221; 231; 321; 331) to the spacing (226; 236) of the centers (224; 225 and 234; 235) of the reflector strips (221; 231; 321; 331).The invention is applicable in particular to bandpass filters with a relative bandwidth on the order of 0.1 percent and to resonators for oscillators.