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:
May. 31, 1988
Filed:
Dec. 19, 1984
Shinji Emori, Urawa, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
A driver for transmitting a digital differential signal along a transmission line during a packet time and not during an idle time while maintaining a constant common voltage between the transmission line and ground throughout the packet and idle time periods. A driving circuit and its drive controller in the driver and respectively formed from paired matched transistors which function as on-off switching circuits and have a common emitter load acting as a constant current source. A collector of a first transistor in the drive controller is connected to the common emitter of the driving circuit and a collector of a second transistor in the drive controller is respectively connected to the collectors of the pair of transistors of the driving circuit through respective matched diodes. During the idle time, the driving circuit is cut off by the first transistor being cut off, and the second transistor carries collector current, which is separated into halves, through respective matched collector resistors in the driving circuit and the matched diodes. The voltage on each collector in the pair of transistors in the driving circuit becomes the mean value of a high and a low voltage levels produced during the packet time. The constant common voltage can be obtained from this mean voltage by using emitter followers. Matched transistors can be used instead of the matched diodes.