Resistance change memory
View Patent ↗According to one embodiment, a resistance change memory includes a memory cell, a sense amplifier and a global bit line. The memory cell is disposed at a location where a local bit line and a word line intersect each other. The memory cell is connected to both the local bit line and the word line. The sense amplifier reads data stored on the memory cell by supplying a read current to the memory cell. The global bit line is connected between the local bit line and the sense amplifier. The global bit line feeds the read current supplied by the sense amplifier to the local bit line. The sense amplifier charges the global bit line, before the local bit line and the global bit line are connected to each other.
1. A resistance change memory comprising:
a first memory cell including a resistance change element;
a word line coupled to the first memory cell, the word line being driven based on an address signal;
a first bit line coupled to the first memory cell and intersecting the word line, the first bit line being selected based on the address signal;
a first inverter including a first input terminal, a first output terminal, and first and second voltage terminals;
a second inverter including a second input terminal, a second output terminal, and third and fourth voltage terminals, the second input terminal being coupled to the first output terminal, the second output terminal being coupled to the first input terminal;
a first MOS transistor coupled to the first output terminal;
a second MOS transistor coupled to the second output terminal;
a third MOS transistor coupled to the first voltage terminal;
a fourth MOS transistor coupled to the third voltage terminal;
a fifth MOS transistor having a current path, one end of which is coupled to the first voltage terminal, the fifth MOS transistor having a gate supplied with a first signal;
a second bit line coupled to another end of the current path; and
a sixth MOS transistor coupled between the second bit line and the first bit line, the sixth MOS transistor having a gate supplied with a second signal,
wherein before the sixth MOS transistor is turned on by the second signal, the fifth MOS transistor is turned on by the first signal.
2. The resistance change memory according to claim 1 , wherein the first voltage terminal supplies a current to the second bit line, thereby charging the second bit line.
3. The resistance change memory according to claim 1 , wherein the first signal includes a read enable signal that permits a read operation, and the second signal includes a column selection signal that selects the first bit line.
4. The resistance change memory according to claim 1 , wherein the fifth MOS transistor includes a transistor that limits a read current flowing through the first memory cell, and the sixth MOS transistor includes a column selection transistor that selects the first bit line.
5. The resistance change memory according to claim 1 , wherein the fifth MOS transistor is turned on through generation of the first signal by using one of the address signal and a signal generated from the address signal.
6. The resistance change memory according to claim 1 , further comprising a seventh MOS transistor coupled between the second bit line and the other end of the current path of the fifth MOS transistor, a constant voltage being applied to a gate of the seventh MOS transistor.
7. The resistance change memory according to claim 1 , further comprising a circuit that feeds a reference current to the third voltage terminal,
wherein data stored on the first memory cell is retained in the first and second inverters, based on a difference between the reference current and a read current flowing through the first voltage terminal during a read operation.
8. The resistance change memory according to claim 1 , further comprising a memory cell array that includes a plurality of memory cells arranged in a matrix form, each of the memory cells having a resistance change element, the memory cells in the memory cell array including the first memory cell.
9. The resistance change memory according to claim 1 , wherein the resistance change element includes a magnetic tunnel junction (MTJ) element the resistance of which is changed through at least one of supply of a current thereto and application of a voltage thereto.
10. A resistance change memory comprising:
a first memory cell including a resistance change element;
a word line coupled to the first memory cell, the word line being driven based on an address signal;
a first bit line coupled to the first memory cell and intersecting the word line, the first bit line being selected based on the address signal;
a first inverter having a first input terminal, a first output terminal, and first and second voltage terminals;
a second inverter having a second input terminal, a second output terminal, and third and fourth voltage terminals, the second input terminal being coupled to the first output terminal, the second output terminal being coupled to the first input terminal;
a first MOS transistor coupled to the first output terminal;
a second MOS transistor coupled to the second output terminal;
a third MOS transistor coupled to the first voltage terminal;
a fourth MOS transistor coupled to the third voltage terminal;
a fifth MOS transistor having a current path, one end of which is coupled to a gate of the third MOS transistor, the fifth MOS transistor having a gate supplied with a first signal;
a second bit line coupled to another end of the current path of the fifth MOS transistor; and
a sixth MOS transistor coupled between the second bit line and the first bit line, the sixth MOS transistor having a gate supplied with a second signal,
wherein before the sixth MOS transistor is turned on by the second signal, the fifth MOS transistor is turned on by the first signal.
11. The resistance change memory according to claim 10 , wherein a current is supplied from the one end of the current path of the fifth MOS transistor to the second bit line, thereby charging the second bit line.
12. The resistance change memory according to claim 10 , wherein the first signal includes a read enable signal that permits a read operation, and the second signal includes a column selection signal that selects the first bit line.
13. The resistance change memory according to claim 10 , wherein the fifth MOS transistor includes a transistor that limits a read current flowing through the first memory cell, and the sixth MOS transistor includes a column selection transistor that selects the first bit line.
14. The resistance change memory according to claim 10 , wherein the fifth MOS transistor is turned on through the first signal generated by using one of the address signal and a signal generated from the address signal.
15. The resistance change memory according to claim 10 , further comprising a seventh MOS transistor coupled to the one end of the current path of the fifth MOS transistor,
wherein before the sixth MOS transistor is turned on, the seventh MOS transistor is turned on.
16. The resistance change memory according to claim 10 , further comprising a seventh MOS transistor coupled between the second bit line and the other end of the current path of the fifth MOS transistor, a constant voltage being applied to a gate of the seventh MOS transistor.
17. The resistance change memory according to claim 10 , further comprising a circuit that applies a reference voltage to a gate of the fourth MOS transistor,
wherein data stored on the first memory cell is retained in the first and second inverters, based on a difference between respective currents flowing through the first output terminal and the second output terminal during a read operation.
18. The resistance change memory according to claim 10 , further comprising a memory cell array that includes a plurality of memory cells arranged in a matrix form, each of the memory cells having a resistance change element, the memory cells in the memory cell array including the first memory cell.
19. The resistance change memory according to claim 1 , wherein the first voltage terminal begins to charge the second bit line when the fifth MOS transistor is turned on by the first signal.
20. The resistance change memory according to claim 10 , wherein the one end of the current path of the fifth MOS transistor begins to charge the second bit line when the fifth MOS transistor is turned on by the first signal.