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. 07, 1989
Filed:
Jan. 05, 1989
Hideo Miwa, Kodaira, JP;
Kazuhiro Tsuruoka, Tokyo, JP;
Koudou Yamauchi, Ohme, JP;
Hitoshi Endoh, Ohme, JP;
Masanori Odaka, Kodaira, JP;
Hitachi, Ltd., Tokyo, JP;
Hitachi VLSI Engineering Corp., Tokyo, JP;
Abstract
A semiconductor memory device includes an input circuit and an output circuit. To prevent the erroneous operation of the input circuit by the noise which develops at the time of the change of the output signal of the output circuit, the threshold voltage of the input circuit is changed, or an internal signal generated by the internal circuit is fixed to a predetermined level. In an output circuit having a tri-state output function, the threshold voltage of the input circuit is changed when the output is brought into the high impedance state, or the internal signal generated by the input circuit is fixed to a predetermined state. Using these arrangements it is possible to prevent the erroneous operation of the input circuit by the noise occurring when the output is brought into the high impedance state. Furthermore, in an output circuit having a tri-state output function, the threshold voltage of the input circuit is changed when the output signal of the output circuit is brought into the high impedance state, too, when the output signal changes. This makes it possible to prevent an erroneous detection of the level of the input signal which might otherwise be caused by the noise.