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:
May. 13, 2008
Filed:
Jul. 12, 2006
Hiroyasu Yoshizawa, Ome, JP;
Satoshi Hanazawa, Hamura, JP;
Hiroyasu Yoshizawa, Ome, JP;
Satoshi Hanazawa, Hamura, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A variable gain amplifier of such configuration that can yield continuously and log-linearly variable gains in relation to control voltage and, at the same time, that does not use an attenuator, an element which otherwise would entail cause of increased noise. The amplifier includes a plurality of gm amplifiers connected in parallel with input signal, exponential multipliers connected respectively to the gm amplifiers, a control section to vary the multiplication coefficient of the exponential multipliers according to the external gain control signal, and an I-V converter circuit to aggregate current output after multiplication and convert the aggregated current output to voltage. A continuously variable gain characteristic can be obtained without the use of an attenuator but by varying multiplication coefficient according to control voltage.