Patent ID: 6891748
Filing Date: 2005-05-10
Classification: G11C

Abstract:
1. A magnetic random access memory comprising: a plurality of cell units, each cell unit including a plurality of cross-point memory cells having first and second terminals and configured to exhibit a magnetoresistive effect; a plurality of word lines, each word line being connected to the first terminals of a corresponding first pluralilty of the cross-point memory cells in each cell unit; a plurality of sub bit lines, each sub bit line being connected to the second terminals of a second corresponding plurality of the cross-point memory cells so as to form sub bit line interconnected units in each cell unit; a plurality of main bit lines, each main bit line being connected to at least one sub bit line interconnected unit in each cell unit by corresponding sub bit lines through first switch circuits and forming a hierarchical bit line structure together with the sub bit lines in each cell unit; a column select circuit configured to select one main bit line and to connect the selected one main bit line to a sense amplifier; and a row select circuit configured to select one word line at a time from a corresponding cell unit connected to a selected cross-point memory cell by controlling selecting circuits during a read operation to set all other word lines in the cell unit having the selected word line to a floating state while maintaining a different state for the one selected word line and to set the word lines in the cell units not having the one selected word line to a same potential as that normally applied to all the main bit lines.