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:
Jun. 01, 1993
Filed:
Jul. 05, 1991
Randall S Fraser, Plantation, FL (US);
Tam-Thanh C Buu, Sunrise, FL (US);
Charles R Ruelke, Davie, FL (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
A crystal filter network comprises at least one variable impedance network (103a, 103b), at least one crystal filter (103c), and a control circuit (110). Each variable impedance network (103a, 103b) has a control terminal, a first terminal (37, 39), and a second terminal (38, 40) for connecting a first impedance (113) coupled to the first terminal (37), to a second impedance coupled to the second terminal (38). The crystal filter (103c) is coupled to at least one of the first and second terminals. Coupled to the control terminal, the control circuit (110) electrically varies (V.sub.1 and V.sub.2) the variable impedance network (103a, 103b) to provide a predetermined impedance characteristic to the crystal filter network (103c).