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:
Dec. 07, 1999
Filed:
Apr. 28, 1998
Zhi-Long Tang, Allentown, PA (US);
Lucent Technologies Inc., Murray Hill, NJ (US);
Abstract
An integrated circuit differential amplifier with a digitally controllable gain. In a preferred embodiment, the differential amplifier employs first and second transconductance (gm) amplifiers and a digital to analog converter (DAC). The first gm amplifier converts a differential input voltage into a differential output current and the second gm amplifier converts the differential output current into a differential output voltage. A digital input code is applied to the DAC to generate an analog output voltage that is applied to one of the gm amplifiers to control its transconductance to thereby control the gain of the differential amplifier. The second gm amplifier employs a pair of low impedance feedback paths between input/output terminals of opposite polarity. The gain of the differential amplifier is thus a function of the ratio of the transconductance of the first gm amplifier to that of the second gm amplifier. Preferably, the same circuit topology is employed for both gm amplifiers, leading to a process- and operating temperature-insensitive differential amplifier gain. Additional gm amplifiers may be connected in parallel with the first gm amplifier to enhance gain. The load resistance presented by the second gm amplifier is preferably kept low to afford high speed operation.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile