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:
May. 25, 2010
Filed:
Jul. 10, 2007
Robert J. Leboeuf, Ii, Salem, NH (US);
Matthew Courcy, Fremont, NH (US);
Robert J. LeBoeuf, II, Salem, NH (US);
Matthew Courcy, Fremont, NH (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A common mode controller circuit () for maintaining a common mode voltage (Vcm) at a first node () and a second node () in a sample-and-hold circuit receiving a pair of AC coupled differential input signals (Vinp, Vinn) includes first and second resistors (R/R) and third and fourth resistors (R/R), each set of resistors connected in series between the first and second nodes, and a differential amplifier (A) having an inverting input terminal coupled to a third node () between the first and second resistors, a non-inverting input terminal coupled to a reference voltage (Vref) and an output terminal coupled to a fourth node () between the third and fourth resistors. The common mode voltage is sampled at the third node and the differential amplifier provides a sourcing output current indicative of the difference between the sampled common mode voltage and the reference voltage to drive the fourth node.