Non-volatile resistance changing for advanced memory applications
A resistance changing memory unit cell includes a resistance changing memory element coupled to a sense bit line and a diode coupled to the resistance changing memory element.
1. A resistance changing memory architecture, comprising:
a plurality of resistance changing memory unit cells coupled between a plurality of sense bit lines and a local current bus, wherein each unit cell comprises:
a resistance changing memory element coupled to the sense bit line; and
a diode coupled to between the resistance changing memory element and the local current bus;
a current control component having a controlled current path that extends between the local current bus and a word line, and a control terminal of the current control component that is operable to control a current conducting through the resistance changing memory element and through the controlled current path from the local current bus to the word line;
wherein the control terminal is configured to receive a plurality of different control signals, and provide a current limiting function comprising a plurality of differing current levels greater than two in response thereto.
2. The memory architecture of claim 1 , wherein the resistance changing memory element comprises a metal-insulator-metal memory element.
3. The memory architecture of claim 2 , wherein the metal-insulator-metal memory element comprises a binary oxide.
4. The memory architecture of claim 1 , wherein the current control component comprises a transistor.
5. The memory architecture of claim 1 , wherein the plurality of unit cells form a unit cell group, and wherein the current control component provides a selective current limiting function for each of the unit cells in the group.
6. The memory architecture of claim 1 , wherein the plurality of unit cells form a unit cell group, and wherein during a read of a selected unit cell within the group the diodes of unselected unit cells within the group operate to block current to the respective resistance changing memory elements of the unselected unit cells.
7. A resistance changing memory array architecture, comprising:
an array of resistance changing memory unit cells, wherein the unit cells are organized in unit cell groups, and wherein each unit cell in a respective group is coupled between a respective sense bit line and a shared local current bus; and
a current control component having a controlled current path that extends between the shared local current bus of a unit cell group and a word line and a control terminal that is operable to control a current conducting through the resistance changing memory element and through the controlled current path from the local current bus to the word line, and configured to selectively limit a current conducting therethrough from one or more of the unit cells in the unit cell group;
wherein the control terminal is configured to receive a plurality of different control signals, and provide a current limiting function comprising a plurality of differing current levels greater than two in response thereto.
8. The array architecture of claim 7 , wherein each unit cell comprises a resistance changing memory element and a diode coupled in series, wherein the diode is oriented to prevent current from passing from the local current bus to the respective sense bit line.
9. The array architecture of claim 7 , further comprising a control circuit configured to provide a read control signal to the current control component during a read operation, wherein the read control signal permits current conduction through the current control component with substantially no limit thereto.
10. The array architecture of claim 9 , further comprising a sense circuit operably coupled to the selected unit cell in the unit cell group during the read operation, and configured to determine a state of the selected unit cell based on a read current sensed therethrough.
11. The array architecture of claim 10 , wherein the sense circuit is configured to determine the state of the selected unit cell by comparing the read current to a plurality of reference currents.
12. The array architecture of claim 7 , further comprising a control circuit configured to couple a unique voltage to the bit line of a selected unit cell in the group during a write operation based on whether the write operation is an erase or a program operation, wherein the unique voltage on the bit line for the erase operation is less than the unique voltage on the bit line for the program operation.
13. The array architecture of claim 12 , wherein the control circuit is further configured to provide a unique control line voltage to a control terminal of the current control component associated with the unit cell group of a selected unit cell during a write operation based on whether the write operation is an erase or a program operation.
14. The array architecture of claim 13 , wherein the control line voltage during the erase operation causes the current control component to not limit the current conducting through the selected unit cell.
15. The array architecture of claim 13 , wherein the control line voltage during the program operation comprises one of a plurality of different values, wherein each of the different value reflect a unique current limit value associated with a desired program state.
16. A resistance changing memory array architecture, comprising:
an array of resistance changing memory unit cells, wherein the unit cells are organized in unit cell groups, and wherein each unit cell in a respective group is coupled between a respective sense bit line and a shared local current bus;
a current control component having a controlled current path that extends between the shared local current bus of a unit cell group and a word line and a control terminal that is operable to control a current conducting through the controlled current path from the local current bus to the word line, and configured to selectively limit a current conducting therethrough from one or more of the unit cells in the unit cell group; and
a sense circuit comprising a transistor having a control terminal and a current path operably coupled to a selected unit cell in the unit cell group during a read operation; the sense circuit configured to determine a state of the selected unit cell by comparing a read current sensed through the selected unit cell to a plurality of reference currents provided on the current path, where the reference currents are generated by applying a plurality of different voltage levels to the control terminal of the transistor.
17. A resistance changing memory array architecture, comprising:
an array of resistance changing memory unit cells, wherein the unit cells are organized in unit cell groups, and wherein each unit cell in a respective group is coupled between a respective sense bit line and a shared local current bus;
a current control component having a controlled current path that extends between the shared local current bus of a unit cell group and a word line and a control terminal that is operable to control a current conducting through a resistance changing memory element and through the controlled current path from the local current bus to the word line, and configured to selectively limit a current conducting therethrough from one or more of the unit cells in the unit cell group; and
a control circuit configured to couple a unique voltage to the bit line of a selected unit cell in the group during a write operation based on whether the write operation is an erase or a program operation, wherein the unique voltage on the bit line for the erase operation is less than the unique voltage on the bit line for the program operation.
18. A resistance changing memory architecture, comprising:
a plurality of resistance changing memory unit cells coupled between a plurality of sense bit lines and a local current bus, wherein each unit cell comprises:
a resistance changing memory element coupled to the sense bit line; and
a diode coupled to between the resistance changing memory element and the local current bus; and
a first current control component coupled between a first location on the local current bus and the wordline; and
a second current control component coupled between a second location on the local current bus and the wordline, wherein the plurality of resistance changing memory unit cells are coupled between the first and second locations on the local current bus.
19. The resistance changing memory architecture of claim 18 , wherein the first current control component comprises:
a controlled current path that extends between the local current bus and a word line, and
a control terminal that is operable to control current conducting through the resistance changing memory elements on the local current bus and through the controlled current path from the local current bus to the word line.