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. 18, 2010
Filed:
Aug. 18, 2008
Katsuji Kimura, Kanagawa, JP;
Katsuji Kimura, Kanagawa, JP;
NEC Electronics Corporation, Kawasaki, Kanagawa, JP;
Abstract
Disclosed is a variable gain circuit, which operates in a region where the gain varies substantially exponentially with respect to a control voltage, having an operation region in which the gain varies substantially with an exponential function{(√{square root over (1−)}−√{square root over (2)})}/{(√{square root over (1+)}−√{square root over (2)})where 0≦K≦1 and x is a variable corresponding to the control voltage. The denominator and the numerator of the above function are given by a first sum current and a second sum current, respectively. The first sum current is a sum of the drain current of a first transistor and a constant current, and the second sum current is a sum of the drain current of a second transistor and the constant current. The first and second transistors have sources grounded, having gates connected common and supplied with a bias voltage, and having back-gates supplied with control voltages differentially.