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. 30, 1987
Filed:
May. 23, 1985
Applicant:
Inventors:
Shigeru Kawami, Kawasaki, JP;
Takashi Tabu, Tokyo, JP;
Mitsutoshi Ayano, Tokyo, JP;
Kiyoshi Shibuya, Kawasaki, JP;
Shin-ichi Itoh, Tokyo, JP;
Assignee:
Fujitsu Limited, Kawasaki, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
379413 ; 379399 ;
Abstract
Battery feed circuit for a pair of subscriber lines includes a voltage drive circuit with an operational amplifier having a predetermined output impedance determined by an alternating current terminal impedance for the pair of subscriber lines. Both voice signals and induced noise signals are terminated by the voltage drive circuit. The voltage drive circuit is connected in parallel with an electronic inductance circuit, between one of the subscriber lines and ground or a direct current voltage supply.