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. 22, 2005
Filed:
Apr. 16, 2003
Curtis R. Leifso, Kanata, CA;
Samuel A. Tiller, Ottawa, CA;
Curtis R. Leifso, Kanata, CA;
Samuel A. Tiller, Ottawa, CA;
Research in Motion Limited, Waterloo, CA;
Abstract
A gain control circuit that permits a variable gain amplifier circuit to operate with high input linearity and low power consumption is disclosed. The variable gain amplifier includes a standard differential bipolar transistor input circuit and a pair of degeneration transistors connected to a current source transistor. The gain control circuit provides a variable degeneration control voltage to vary the effective resistance of the degeneration transistors and a variable bias voltage to vary the current of the current source transistor. The input linearity of the variable gain amplifier is controlled independently of gain by adjusting the effective resistance and the current in an inverse relationship such that at maximum gain the current is at a maximum while the degeneration resistance is at a minimum, and at minimum gain the current is at a minimum while the degeneration resistance is at a maximum. Therefore the variable gain amplifier can be controlled to operate with high input linearity and low power at lower ranges of gain.