US 7,453,719 B2Granted

Magnetic random access memory with improved data reading method

AssigneeNEC Corporation

InventorsNoboru Sakimura, Takeshi Honda, Tadahiko Sugibayashi

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Abstract

An MRAM has a plurality of bit lines, a reference bit line, a plurality of memory cells and reference cells and a read section. The memory cells are provided along the bit lines and the reference cells along the reference bit line. The memory cell and reference cell have a tunneling magnetic resistance and a reference tunneling magnetic resistance, each of which has a spontaneous magnetization whose direction is reversed in accordance with data stored therein. The read section has a first resistance section which contains a ninth terminal connected with a bit line and a tenth terminal connected with the first power supply, a second resistance section which contains an eleventh terminal connected with the reference bit line and a twelfth terminal connected with the first power supply, and a comparing section which compares a sense voltage on the ninth terminal and a reference voltage of the eleventh terminal.

Claims36

Dependent claims

A magnetic random access memory comprising:

a plurality of bit lines extending in a first direction;
a reference bit line extending in the first direction;
a plurality of memory cells provided along said plurality of bit lines;
a plurality of reference cells provided along said plurality of reference bit lines;
and
a read section,
wherein each of said plurality of memory cells has a first tunneling magnetic resistance which has spontaneous magnetization whose direction is reversed in accordance with data to be stored to take a first state or a second state, and is connected to one of said plurality of bit lines in a read operation,
each of said plurality of reference cells has a reference tunneling magnetic resistance which has spontaneous magnetization whose direction is reversed in accordance with data to be stored to take the first state or the second state and is connected to one of said plurality of reference bit lines in the read operation,
said read section comprises:
a first resistance section having a first resistance value and having a ninth terminal serving as one terminal connected to a selected bit line and a tenth terminal serving as the other terminal connected to a first power supply in the read operation;
a second resistance section having a second resistance value different from the first resistance value and having an eleventh terminal serving as one terminal connected to said reference bit line and a twelfth terminal serving as the other terminal connected to the first power supply in the read operation;
and
a comparing section configured to compare a sense voltage serving as a voltage of the ninth terminal with a reference voltage serving as a voltage of the eleventh terminal,
wherein when the data stored in a selected cell is read out, said read section generates said sense voltage by dividing the voltage of the first power supply by said first tunneling magnetic resistance and said first resistance section of the selected cell, and said reference voltage by dividing the voltage of the first power supply by said reference tunneling magnetic resistance and said second resistance section of a selected reference cell, and outputs a comparison result between said sense voltage and said reference voltage, and
said selected cell is selected from said plurality of memory cells and said selected reference cell is selected from said plurality of reference cells.

12 more elements

A magnetic random access memory comprising:

a plurality of bit lines extending in a first direction;
a reference bit line extending in the first direction;
a plurality of memory cells provided along said plurality of bit lines;
a plurality of reference cells provided along said plurality of reference bit lines;
and
a read section,
wherein each of said plurality of memory cells has a first tunneling magnetic resistance which has spontaneous magnetization whose direction is reversed in accordance with data to be stored to take a first state or a second state, and is connected to one of said plurality of bit lines in a read operation,
each of said plurality of reference cells has a reference tunneling magnetic resistance which has spontaneous magnetization whose direction is reversed in accordance with data to be stored to take the first state or the second state and is connected to one of said plurality of reference bit lines in the read operation,
said read section comprises:
a first resistance section having a first resistance value and having a ninth terminal serving as one terminal connected to a selected bit line and a tenth terminal serving as the other terminal connected to a first power supply in the read operation;
a second resistance section having a second resistance value different from the first resistance value and having an eleventh terminal serving as one terminal connected to said reference bit line and a twelfth terminal serving as the other terminal connected to the first power supply in the read operation;
and
a comparing section configured to compare a sense voltage serving as a voltage of the ninth terminal with a reference voltage serving as a voltage of the eleventh terminal,
wherein said first resistance section has a spontaneous magnetization whose direction is reversed to take the first state or the second state and has a second tunneling magnetic resistance and a third tunneling magnetic resistance connected in series, and
said second resistance section has a spontaneous magnetization whose direction is reversed to take the first state or the second state and has a fourth tunneling magnetic resistance and a fifth tunneling magnetic resistance connected in series.

12 more elements

A magnetic random access memory comprising:

a plurality of bit lines extending in a first direction;
a reference bit line extending in the first direction;
a plurality of memory cells provided along said plurality of bit lines;
a plurality of reference cells provided along said plurality of reference bit lines;
and
a read section,
wherein each of said plurality of memory cells has a first tunneling magnetic resistance which has spontaneous magnetization whose direction is reversed in accordance with data to be stored to take a first state or a second state, and is connected to one of said plurality of bit lines in a read operation,
each of said plurality of reference cells has a reference tunneling magnetic resistance which has spontaneous magnetization whose direction is reversed in accordance with data to be stored to take the first state or the second state and is connected to one of said plurality of reference bit lines in the read operation,
said read section comprises:
a first resistance section having a first resistance value and having a ninth terminal serving as one terminal connected to a selected bit line and a tenth terminal serving as the other terminal connected to a first power supply in the read operation;
a second resistance section having a second resistance value different from the first resistance value and having an eleventh terminal serving as one terminal connected to said reference bit line and a twelfth terminal serving as the other terminal connected to the first power supply in the read operation;
and
a comparing section configured to compare a sense voltage serving as a voltage of the ninth terminal with a reference voltage serving as a voltage of the eleventh terminal,
wherein said read section comprises:
a first constant voltage section configured to apply a second voltage between the ninth terminal and said plurality of memory cells and between the eleventh terminal and said plurality of reference cells;
a first current section provided between said first constant voltage section and the ninth terminal to supply said selected bit line and said first resistance section with a current having a same magnitude;
and
a second current section provided between said first constant voltage section and the eleventh terminal to supply said reference bit line and said second resistance section with a current having a same magnitude.

15 more elements

Dependencies are inferred from the claim text.