Kabushiki Kaisha Toshiba

Takenori Nakamura

Kenichi Nakamura

Youichi Suzuki

Hiroshi Takamoto

A cascade sense amplifier includes section separated sense amplifiers, a cascade wiring and a main sense amplifier. The main sense amplifier has a capacitance regulation element provided at a base potential of input transistors constituting a data input end. The element is comprised of a metal oxide semiconductor (MOS) transistor for forming a capacitance corresponding to a potential V.sub.SS mainly forming a capacitance by the cascade wiring. A size of the element is determined in the manner that the base potential drop time of the transistors is equal to a potential drop time of the cascade wiring when a power source voltage V.sub.CC drops. Even though the power source voltage V.sub.CC drops, the transistors have no cut-off condition so as to prevent the read-out time from delaying. Especially, if the element is comprised of a MOS transistor, it is possible to use an extremely thin gate insulation layer as a dielectric, thereby suppressing an increase of a chip size.

Cascade sense amplifier for reading out data stored in semiconductor

The memory device of this invention includes a plurality of memory cell blocks each having a plurality of memory cells disposed in a matrix form. A memory cell selector selects a predetermined number of the memory cells in each memory cell block in accordance with external address signals. A sense amplifier unit amplifies data read from the selected memory cells for data read. A data output unit outputs the data amplified by the sense amplifier unit. A block selector selects a desired one or more of the memory cell blocks as data write blocks for data write. A data write unit writes data in the selected memory cells in the selected blocks. A sense amplifier controller supplies, during the data write, a signal to the sense amplifier unit to make the sense amplifier unit inactive, and during the data read supplies a signal to the sense amplifier unit to make the sense amplifier unit active.

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Yokohama, Japan

Takenori Nakamura