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:
Dec. 28, 2004
Filed:
Jun. 04, 2003
Kazuo Kawai, Tokyo, JP;
General Research of Electronics, Inc., Tokyo, JP;
Abstract
In order to improve Q of a tuning circuit by using a negative resistance circuit, a tuning circuit wherein a frequency selectivity characteristic and a tuning circuit gain does not vary and are kept constant values even if a tuning frequency is changed, is provided. The tuning circuit is constructed so as to compensate a series resistance component by connecting a negative resistance circuit to a series resonance circuit. The negative resistance circuit includes a differential amplifying circuit having two transistors emitters of which are connected in common, and a low output impedance circuit such as an emitter follower. The low impedance output is fed back to a same phase input side of the differential amplifying circuit directly and also to an inverse phase input side thereof to obtain a negative resistance value at this inverse input terminal.