Semiconductor memory apparatus and method for writing in the memory

Abstract

A phase change memory of high compatibility with DRAM. If a cell MC0, connected to a word line WL0L, is of a low resistance, current flowing through it is higher than that flowing in a dummy cell MR0, and hence a bit line SA_B is at a potential lower than that of a bit line SA_T. This difference is amplified by a sense amplifier SA and read out. Immediately before latching cell data by the sense amplifier, an NMOS transistor MN1 is turned off to disconnect a memory cell part from a sense amplifier part. An NMOS transistor MN10 then is turned on so that data on the selected word line are all in the set state. If then writing is to be carried out, writing is carried out in the sense amplifier SA from signal lines LIO and RIO, which are I/O lines. However, writing is not performed in the memory cells. Before a precharge command is entered to precharge the word line WL0L, under, the NMOS transistor MN1 is again turned on to write reset in the cell MC0.

Dependencies are inferred from the claim text.