Resistive memory devices having address-dependent parasitic resistance compensation during programming
An integrated circuit memory device includes an array of resistive memory cells and a programming circuit, which is electrically coupled by a plurality of word lines and plurality of bit lines to corresponding rows and columns of the resistive memory cells. The programming circuit includes a control circuit and word line driver that are collectively configured to generate word line program voltages having magnitudes that vary as a function of the row and/or column addresses of the resistive memory cells in the array, during operations to program the array with write data. According to the function, the magnitude of a word line program voltage associated with a first resistive memory cell having a first parasitic resistance is less than a magnitude of a word line program voltage associated with a second resistive memory cell having a second parasitic resistance, which is greater than the first parasitic resistance.
1. An integrated circuit memory device, comprising:
an array of resistive memory cells having at least one group of resistive memory cells therein; and
a programming circuit electrically coupled by a plurality of word lines and a plurality of bit lines to corresponding rows and columns of resistive memory cells in said array, said programming circuit comprising a control circuit and word line driver that are collectively configured to generate word line program voltages having magnitudes that vary as a function of the row and/or column addresses of the resistive memory cells in said array, during operations to program said array with write data using a mapping table that associates memory cell addresses to corresponding parasitic resistances that vary according to distances between respective resistive memory cells and a row decoder, which is electrically coupled by the plurality of word lines to said array of resistive memory cells;
wherein the at least one group of resistive memory cells is divided into n regions that are each associated with different parasitic resistances within the mapping table, where n is a positive integer greater than one.
2. The memory device of claim 1 , wherein, according to the function, a magnitude of a word line program voltage associated with a first resistive memory cell having a first parasitic resistance associated therewith is less than a magnitude of a word line program voltage associated with a second resistive memory cell having a second parasitic resistance associated therewith, which is greater than the first parasitic resistance.
3. The memory device of claim 2 , wherein said word line driver comprises a voltage generator configured to generate the word line program voltages in response to multi-bit program voltage control signals generated by the control circuit during the operations to program said array with write data.
4. The memory device of claim 3 , wherein said word line driver is responsive to the word line program voltages generated by the voltage generator and address signals generated by the control circuit.
5. The memory device of claim 1 , wherein said word line driver comprises a voltage generator configured to generate the word line program voltages in response to multi-bit program voltage control signals generated by the control circuit during the operations to program said array with write data.
6. The memory device of claim 5 , wherein said word line driver is responsive to the word line program voltages generated by the voltage generator and address signals generated by the control circuit.
7. A resistive memory device comprising:
a memory cell array including a plurality of memory cells;
a control circuit configured to generate a program voltage control signal corresponding to an address of a selected memory cell among the plurality of memory cells, based on a mapping table defining a parasitic resistance according to an address of each of the plurality of memory cells;
a voltage generator configured to generate a program voltage having a first program voltage level among a plurality of program voltage levels, based on the program voltage control signal; and
a row decoder configured to provide the program voltage to a selected word line connected to the selected memory cell;
wherein the memory cell array includes a plurality of memory groups, and the mapping table is defined with respect to one of the plurality of memory groups and is commonly applied to the plurality of memory groups; and
wherein each of the memory groups is divided into n regions having different parasitic resistances by the mapping table, and n is an integer of 2 or more.
8. The resistive memory device of claim 7 , wherein a parasitic resistance of the selected memory cell is changed according to a distance between the selected memory cell and the row decoder, and
as the parasitic resistance is smaller, the first program voltage level increases based on the program voltage signal.
9. The resistive memory device of claim 7 , further comprising a write circuit configured to provide a program current to a selected bit line connected to the selected memory cell.
10. The resistive memory device of claim 9 , wherein, when a cell resistance of the selected memory cell is smaller than or equal to a reference resistance, a cell current flowing through the selected memory cell is equal to the program current, and
when the cell resistance is larger than the reference resistance, the cell current is smaller than the program current.
11. The resistive memory device of claim 10 , wherein the reference resistance corresponds to a median of a cell resistance distribution of the plurality of memory cells.
12. The resistive memory device of claim 9 , further comprising a column decoder configured to electrically connect the write circuit to the selected bit line,
wherein the parasitic resistance of the selected memory cell is changed according to at least one of the distance between the selected memory cell and the row decoder, and a distance between the selected memory cell and the column decoder, and
as the parasitic resistance is smaller, the first program voltage level increases based on the program voltage signal.
13. The resistive memory device of claim 7 , wherein the value of n is determined based on a cell resistance distribution of the plurality of memory cells and the parasitic resistances.
14. The resistive memory device of claim 7 , wherein the program voltage control signal is an M-bit signal, and 2 M is greater than or equal to n.
15. A resistive memory device comprising:
a memory cell array including a plurality of memory cells;
a control circuit configured to generate a program voltage control signal corresponding to an address of a selected memory cell among the plurality of memory cells, based on a mapping table defining a parasitic resistance according to an address of each of the plurality of memory cells;
a voltage generator configured to generate a program voltage having a first program voltage level among a plurality of program voltage levels, based on the program voltage control signal; and
a row decoder configured to provide the program voltage to a selected word line connected to the selected memory cell;
wherein the voltage generator includes:
a voltage divider including a plurality of resistors connected in series between a first voltage terminal and a second voltage terminal, and configured to output a plurality of voltages corresponding to the plurality of program voltage levels; and
a switch group including a plurality of switches connected between the voltage divider and an output terminal and turned on and off according to the program voltage control signal, and configured to output the program voltage to the output terminal.