Dual word line mode for DRAMs
View Patent ↗An integrated circuit memory includes circuitry for individually activating word lines in a first one memory cell per bit operational mode, simultaneously activating at least two word lines in a second operational mode where two or more memory cells are dedicated to each data bit, and providing a word line sequence when first converting stored data in the array of memory cells from the first operational mode to the second operational mode. The word line sequence includes activating a first word line, developing a valid signal on a corresponding bit line, and then activating a second word line while the first word line is still active.
1. An integrated circuit memory comprising:
a plurality of bit lines;
a plurality of word lines;
a plurality of memory cells each coupled to one of the plurality of bit lines and to one of the plurality of word lines;
row decoder circuitry for individually activating the word lines in a first operational mode and for simultaneously activating at least two word lines in a second operational mode; and
means for providing a word line sequence when first converting stored data in the plurality of memory cells from the first operational mode to the second operational mode.
2. The integrated circuit memory of claim 1 in which the first operational mode comprises a one memory cell per bit operational mode.
3. The integrated circuit memory of claim 1 in which the second operational mode comprises a two memory cell per bit operational mode.
4. The integrated circuit memory of claim 1 in which the second operational mode comprises a four memory cell per bit operational mode.
5. The integrated circuit memory of claim 1 in which the second operational mode comprises an eight memory cell per bit operational mode.
6. The integrated circuit memory of claim 1 in which the row decoder circuitry includes an address predecoder.
7. The integrated circuit memory of claim 6 in which the address predecoder further comprises:
a first address input;
a second address input;
an output; and
a control signal input.
8. The integrated circuit memory of claim 7 in which the output provides an output signal that is the logical combination of the data states of the first and second address inputs, and the control signal input receives a control signal for forcing the data state of the output signal.
9. The integrated circuit memory of claim 1 in which the means for providing a word line sequence comprises a means for activating a first word line, developing a valid signal on a corresponding bit line, and then activating a second word line while the first word line is still active.
10. The integrated circuit memory of claim 1 further comprising means for permanently forcing the integrated circuit memory to remain in the second operational mode.
11. A method of operating an integrated circuit memory including a plurality of bit lines, a plurality of word lines, and a plurality of memory cells each coupled to one of the plurality of bit lines and to one of the plurality of word lines, the method comprising:
individually activating the word lines in a first operational mode;
simultaneously activating at least two word lines in a second operational mode; and
providing a word line sequence when first converting stored data in the plurality of memory cells from the first operational mode to the second operational mode.
12. The method of claim 11 in which individual word lines are activated to provide a one memory cell per bit operational mode in the first operational mode.
13. The method of claim 11 in which two word lines are simultaneously activated to provide a two memory cell per bit operational mode in the second operational mode.
14. The method of claim 11 in which four word lines are simultaneously activated to provide a four memory cell per bit operational mode in the second operational mode.
15. The method of claim 11 in which eight word lines are simultaneously activated to provide an eight memory cell per bit operational mode in the second operational mode.
16. The method of claim 11 in which providing a word line sequence comprises activating a first word line, developing a valid signal on a corresponding bit line, and then activating a second word line while the first word line is still active.
17. The method of claim 11 further comprising permanently forcing the integrated circuit memory to remain in the second operational mode.
18. A predecoder for an integrated circuit memory for switching between a first operational mode and a second operational mode comprising:
an input section having first and second address inputs; and
an output section coupled to the input section having a control signal input and an output for providing an output signal,
wherein the output signal is responsive to the data states of the first and second address inputs in the first operational mode, and the output signal is forced to a data state in response to control signal on the control signal input in the second operational mode.
19. The predecoder of claim 18 wherein the input section comprises first, second, third, and fourth cascode-coupled transistors, wherein a gate of the first transistor receives a first address signal, a gate of the second transistor receives a second address signal, a gate of the third transistor receives the second address signal, and a gate of the fourth transistor receives the control signal.
20. The predecoder of claim 18 wherein the output section comprises first and second cascode-coupled transistors, wherein a gate of the first transistor receives the control signal, and a gate of the second transistor receives a first address signal.