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.

Date of Patent:
Feb. 07, 2017

Filed:

Nov. 07, 2014
Applicant:

Altera Corporation, San Jose, CA (US);

Inventor:

Vishal Giridharan, San Jose, CA (US);

Assignee:

Altera Corporation, San Jose, CA (US);

Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H03F 3/45 (2006.01); H03G 3/00 (2006.01);
U.S. Cl.
CPC ...
H03F 3/45636 (2013.01); H03G 3/007 (2013.01); H03F 2203/45074 (2013.01); H03F 2203/45154 (2013.01);
Abstract

A variable gain amplifier circuit includes a differential pair of transistors and a variable current source circuit. The differential pair of transistors generates an output signal based on an input signal. The variable current source circuit is coupled to the differential pair of transistors. A gain of the output signal relative to the input signal varies in response to variations in a bias current through the variable current source circuit. The variable gain amplifier circuit maintains a common mode voltage of the output signal substantially constant in response to the variations in the bias current through the variable current source circuit.


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