Magnetoresistive memory cell array and MRAM memory comprising such array
View Patent ↗The present invention describes a matrix with magnetoresistive memory cells arranged in logically organized rows and columns, Each memory cell includes a magnetoresistive element. The matrix comprises means for simultaneously reading from one cell in a column and writing to another cell in a column, or means for simultaneous reading from one cell in a row and writing to another cell in the same row. Such matrix can be used in a read-while-write MRAM memory.
1. A matrix ( 38 ) with magnetoresistive memory cells arranged in logically organized rows and columns, each memory cell including a magnetoresistive element ( 2 ), furthermore comprising means for simultaneously reading from one cell in a column and writing to another cell in a column, or means for simultaneous reading from one cell in a row and writing to another cell in the same row.
2. A matrix ( 38 ) according to claim 1 , wherein the means for simultaneously reading and writing in a row or a column comprise a first column line ( 34 ) and a second column line ( 32 ) for each column, the first column line ( 34 ) being a write bit line and the second column line ( 32 ) being a read bit line,
the first column line ( 34 ) being a continuous conductive strip which is magnetically couplable to the magnetoresistive element ( 2 ) of each of the memory cells of the column,
the second column line ( 32 ) being a continuous conductive strip which is electrically couplable to an electrode of each of the same magnetoresistive elements ( 2 ) of the memory cells of the column to which the first column line ( 34 ) is magnetically couplable.
3. A matrix ( 38 ) according to claim 2 , wherein each row has a digit line ( 4 ) and a word line ( 8 ) and each cell has a switching element (T) for connecting another electrode of the magnetoresistive element ( 2 ) to a voltage source ( 24 ), the digit line ( 4 ) being a continuous conductive strip which is magnetically couplable to the magnetoresistive element ( 2 ) of each of the memory cells of a row and the word line ( 8 ) being a continuous strip electrically connected to each of the switching elements (T) of a row.
4. A matrix ( 38 ) according to claim 2 , wherein a closest approach distance of the first column line ( 34 ) to the magnetoresistive element ( 2 ) of a cell is smaller than a closest approach distance of the second column ( 32 ) line to the same magnetoresistive element ( 2 ).
5. A matrix ( 38 ) according to any of the previous claims, wherein the magnetoresistive elements ( 2 ) comprise a magnetic tunnel junction (MTJ).
6. A read-while-write MRAM memory comprising a matrix ( 38 ) according to any of the previous claims and selecting circuitry for selecting a cell to be read and a cell to be written.
7. A read-while-write MRAM memory according to claim 6 , wherein the selecting circuitry comprises a row select decoder ( 46 ) and a column select decoder ( 42 ).
8. A read-while-write MRAM memory according to claim 3 , wherein the selecting circuitry is adapted to provide electrical energy to the first and second column lines ( 34 , 32 ), the digit lines ( 4 ) and the word lines ( 8 ) for simultaneous reading of one cell in a column and writing to another cell in the same column or reading from one cell in a row and writing to another cell in the same row.
9. A read-while-write MRAM memory according to claim 8 , wherein a row current source ( 48 ) is connected to the row select decoder ( 46 ) for providing a selected digit line ( 4 ) with electrical energy.
10. A read-while-write MRAM memory according to claim 8 , wherein a write bit line current source ( 44 ) is connected to the column select decoder ( 42 ) for providing a selected write bit line ( 34 ) with electrical energy.
11. A read-while-write MRAM memory according to claim 6 , furthermore comprising sense amplifiers ( 50 ) connectable to the second column lines ( 32 ).
12. A method of operating a matrix ( 38 ) with magnetoresistive memory cells arranged in logically organized rows and columns, each cell including a magnetoresistive element ( 2 ), comprising simultaneously reading from one cell in a column and writing to another cell in the same column or simultaneously reading from one cell in a row and writing of another cell in the same row.
13. A method according to claim 12 , furthermore comprising selecting one row for reading and another row for writing or selecting one column for reading and another column for writing.
14. A method according to claim 13 , wherein the selecting step includes providing electrical energy to a write bit line ( 34 ) which is magnetically couplable to the magnetoresistive element ( 2 ) to be written, to a read bit line ( 32 ) which is electrically couplable to a first electrode of the magnetoresistive element ( 2 ) to be read, to a digit line ( 4 ) which is magnetically couplable to the memory element ( 2 ) to be written and to a word line ( 8 ) which is electrically connected to a switching element (T) for connecting a second electrode of the magnetoresistive element ( 2 ) to be read to a voltage source ( 24 ).