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:
Jun. 17, 2003
Filed:
Feb. 28, 2002
Daniel M. Joffe, Owens Crossroads, AL (US);
Jared Daniel Cress, Decatur, AL (US);
Adtran, Inc., Huntsville, AL (US);
Abstract
The present invention provides a slope equalizer for use in a voice frequency channel card, which is preferably electronically and remotely controllable, and retrocompatible with existing telecommunication systems. The slope equalizer of the invention includes a high-pass filter followed by a variable gain stage amplifier, where the variable gain stage amplifier is an operational amplifier with a plurality of parallel input signal paths, each of the signal paths being a series-connected resistor and switch. The switch is preferably a FET transistor that is electronically and, optionally, remotely controllable. The circuit topology allows the use of FET transistors having relatively high on-resistances. A further advantage of the topology is that the FET switches are connected to a virtual ground by way of an operational amplifier, thereby reducing on-resistance modulation caused by signal variations across the FET.