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:
Jul. 08, 2003
Filed:
Sep. 09, 1999
Tsutomu Kawano, Tokyo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A semiconductor integrated circuit in which a band-pass filter, a sound detector, and some other circuits are formed on a single semiconductor substrate. The output signal from an AM detector is passed through a high-pass filter to obtain, substantially, an FM sound signal. A gain variable amplifier controls the amplitude of the FM sound signal and passes the signal through the band-pass filter to extract substantially, an FM sound carrier signal. The amplitude detector monitors the amplitude of the sound carrier signal and applies negative feedback to the gain variable amplifier so that the amplitude is kept constant. Thus, the influence of noise from the band-pass filter is reduced, and degradation of signal-to-noise ratio can be prevented.