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:
Feb. 10, 2009
Filed:
Feb. 08, 2007
Wee Liang Lien, Singapore, SG;
Rawinder Dharmalinggam, Singapore, SG;
Ten Voon Wong, Oakville, CA;
MediaTek Singapore Pte Ltd, Aver Rajah Cresent, SG;
Abstract
A variable gain amplifying circuit comprises two stages, a first stage and a second stage with a common voltage-to-current converter. Each stage comprises two BJTs, two voltage controlled current sources, a variable resistor with a variable resistance, and the common voltage-to-current converter. The two BJTs construct a differential amplifier for amplifying a pair of differential signals. The variable resistor with the variable resistance is connected between the emitters of the two BJTs wherein the variable resistance of the variable resistor is represented as R. The variable resistance Ris controlled by a control voltage V. The two voltage controlled current sources are respectively connected between the corresponding emitter of BJTs and ground. The currents respectively through the voltage controlled current sources are equal to each other and represented as I. The current Iis controlled by the common voltage-to-current converter according the control voltage V. The variable resistance Rand the current Iof the voltage controlled current sources can be varied simultaneously by the control voltage Vso as to rapidly adjust the gain of the variable gain amplifying circuit.