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:
Sep. 13, 1994
Filed:
Sep. 03, 1992
Fujitsu Limited, Kawasaki, JP;
Abstract
A battery feed circuit supplies a feed current to a telephone set via a 2-wire telecommunication line formed of a TIP line and a RING line. The battery feed circuit includes a first voltage detection circuit for detecting a first voltage across the TIP line and a ground line, a second voltage detection circuit for detecting a second voltage across the RING line and a power line connected to a power supply of the battery feed circuit, a current source responsive to a first control signal for respectively generating first and second currents in the TIP and RING lines, the first and second currents being equal in magnitude and opposite in direction, the current source also varying the first and second currents in response to a second control signal so as to be in proportion to a common mode voltage across the TIP and RING lines, a first feedback circuit responsive to the first and second voltages detected by the first and second voltage detection circuits for generating the first control signal, and a second feedback circuit for generating the second control signal by detecting the common mode voltage across the TIP and RING lines.