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:
Nov. 19, 1985
Filed:
Jul. 23, 1984
Applicant:
Inventor:
Douglas C Smith, Rumson, NJ (US);
Assignee:
AT&T Information Systems Inc., Holmdel, NJ (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
179 / ; 179 70 ; 307 15 ;
Abstract
Resistive battery feed circuits are normally not used because of lack of power supply noise rejection and attendant crosstalk coupling. In this circuit the opamp and surrounding circuitry insure that power supply and ground noise do not couple into the tip and ring circuits as a metallic signal and improve crosstalk attenuation. In addition, the opamp is used to split the 48 volt supply.