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:
Mar. 23, 1993
Filed:
Aug. 29, 1991
Masanori Fujisawa, Kumagaya, JP;
Sanyo Electric Co., Ltd., Osaka, JP;
Abstract
An amplifying circuit with a small current consumption which is used for a portable radio, personal stereo systems or the like. The operating current of a differential amplifier, which is the main component of the amplifying circuit, is controlled by a first current circuit, which is a fixed constant-current source, and a second current circuit, which is a variable current source. The current of the second current circuit is controlled by an input audio signal with the voltage subjected to full-wave rectification. As a result, when the amplitude of the input signal is small, only a slight operating current is consumed by the first current circuit, thereby saving electricity. On the other hand, when the amplitude of an input audio signal is large, the current of the second current circuit also increases therewith, so that the amplifier flows a sufficiently large output current. Thus, it is possible to amplify the current in correspondence with the amplitude of an input signal, while reducing the operating current when the amplitude of an input signal is small, thereby reducing the current consumption.