Back to results
US 6,807,088 B2Granted
Magnetic random access memory and reading method thereof
AssigneeKabushiki Kaisha Toshiba
InventorKenji Tsuchida
Life of this patent
Estimating the term…
Abstract
Reference cells are provided in a memory cell array. When the data is read, the data in the reference cells are inverted, thereby preventing the data in the selected cell from changing. This makes it possible to decrease the number of write operations and realize a high-speed read operation and lower power consumption.
Claims21
A magnetic random access memory device comprising:
- a memory cell array in which a plurality of memory cells producing a magnetoresistive effect are arranged in a matrix;
- a plurality of reference cells which are provided in a part of the memory cell array and store data to be referred to when the memory cells are read from;
- word lines arranged in each row of the memory cell array;
- bit lines arranged in each column of the memory cell array;
- a row decoder to selectively drive the word lines;
- a column decoder to select the bit lines;
- a sense amplifier to sense the data in the selected memory cell and the data in the selected reference cell;
- a first data buffer to hold the data outputted from the sense amplifier;
- a controller which reads the data from the selected memory cell and then inverts the data in the selected reference cell;
- a second data buffer to hold the data outputted from the sense amplifier according to the data in the selected memory cell and the inverted data in the reference cell;
- and
- a comparator to compare the output data of the first data buffer and that of the second data buffer and determine the data read from the selected cell.
9 more elements
A magnetic random access memory device comprising:
- word lines arranged in each row of a memory cell array;
- bit lines arranged in each column of the memory cell array;
- a row decoder to selectively drive the word lines;
- a column decoder to select the bit lines;
- a plurality of memory cells producing a magnetoresistive effect which are arranged at half of the intersections of the word lines and the bit lines;
- a plurality of reference cells which are provided in a part of the memory cell array, are selected by dedicated word lines, and store data to be referred to when the memory cells are read from;
- a sense amplifier to sense the data in the selected memory cell and the data in the selected reference cell;
- a first data buffer to hold the data outputted from the sense amplifier;
- a controller which reads the data from the selected memory cell and then inverts the data in the selected reference cell;
- a second data buffer to hold the data outputted from the sense amplifier according to the data in the selected memory cell and the inverted data in the reference cell;
- and
- a comparator to compare the output data of the first data buffer and that of the second data buffer and determine the data read from the selected cell.
9 more elements
The magnetic random access memory device according to claim 15, wherein
- each data register includes:
- a latch circuit having a first and a second junction node, and
- a transistor having one end connected to the first junction node of the latch circuit and which sets initial data in the latch circuit when the power is turned on, and
- a control circuit includes:
- a delay circuit connected to the second junction node of the latch circuit, and
- a logic circuit to control potentials at the first and second junction nodes of the latch circuit according to a clock signal and the output signal of the delay circuit.
3 more elements
A magnetic random access memory reading method comprising:
- sensing the difference between the data read from a selected cell and the data read from a reference cell in a first read operation;
- writing the reverse of the data read from the selected cell in the first read operation into the reference cell;
- sensing the difference between the data read from the selected cell and the data read from the reference cell in a second read operation;
- and
- determining the data stored in the selected cell from whether the difference between the data sensed in the first operation is larger or smaller than the difference between the data sensed in the second read operation.
2 more elements
Dependencies are inferred from the claim text.