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. 22, 1988
Filed:
Jul. 09, 1986
Yoshihiro Takemae, Tokyo, JP;
Masao Nakano, Kawasaki, JP;
Kimiaki Sato, Tokyo, JP;
Nobumi Kodama, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
A semiconductor dynamic memory device having an improved refreshing time is disclosed wherein the memory device provides two buffer memories exclusively for the external and refresh addresses, each of the buffer memories comprising a preamplifier and a driver stage. When the falling edge of a RAS signal is detected, all the circuits are enabled in parallel, but the operation of the driver is suppressed. As soon as a CAS before RAS detector discriminates which of the falling edges of the CAS and RAS signals becomes low earlier, it sends an address driving signal to one of the drivers, and the external address or refresh address are sent immediately. Using this technique, the prior art sequential operation of discriminating the falling edges of RAS and CAS signal, sending the refresh signal, receiving it and switching the circuit from external address to refresh address is eliminated, and is replaced by a parallel operation. Thus the set up time of the dynamic memory is reduced to 1-2 n.sec. by the present invention.