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. 21, 1999
Filed:
Jul. 09, 1998
Edison Fong, Sunnyvale, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A unity gain analog signal amplifier for low voltage applications, with no DC level shifting so as to preserve dynamic range, a large bandwidth, a good driving capability for capacitive loads and a rail-to-rail output voltage range. A differential amplifier composed of matched MOSFETs is biased between current source and sink circuits. The current source is a current mirror which provides equal currents through the two branches of the differential amplifier, while the tail current is sunk by the current sink circuit. The analog input signal drives the gate terminal of one of the MOSFETs and the gate and drain terminals of the other MOSFET are connected together and provide the output signal. An additional current mirror branch driven by the current source and connected to the output terminal provides increased output current driving capacity and output voltage pull up. With two such circuits connected in a symmetrical push-pull configuration, output current sourcing and sinking as well as output voltage pull up and pull down capabilities are realized.