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:
Jul. 23, 1985
Filed:
Oct. 04, 1983
Apparajan Ganesan, Indianapolis, IN (US);
AT&T Technologies, Inc., Berkeley Heights, NJ (US);
Abstract
A switched capacitor biquadratic filter (10; 20) includes means for dynamically shifting the level of the input voltage (V.sub.B, V.sub.D ; V.sub.X, V.sub.Y,) of the amplifiers (12, 14), so that the need for a level shifting stage in the amplifiers (12; 14) is eliminated. The normally grounded nodes associated with the input ports of the amplifiers (12; 14) are set to a reference voltage (V.sub.B, V.sub.D ; V.sub.X, V.sub.Y) which shifts the inputs to a level appropriate to result in an analog grounded voltage at the outputs of the amplifiers. Internal level shifting stages are thereby eliminated from the amplifiers (12; 14). This gives the filter (10, 20) a broader operating frequency range. Also disclosed is a particular design for the amplifiers (12, 14) which includes a folded cascode mirror configuration.