Dynamic data restore in thyristor-based memory device
View Patent ↗A dynamically-operating restoration circuit is used to apply a voltage or current restore pulse signal to thyristor-based memory cells and therein restore data in the cell using the internal positive feedback loop of the thyristor. In one example implementation, the internal positive feedback loop in the thyristor is used to restore the conducting state of a device after the thyristor current drops below the holding current. A pulse and/or periodic waveform are defined and applied to ensure that the thyristor is not released from its conducting state. The time average of the periodic restore current in the thyristor may be lower than the holding current threshold. While not necessarily limited to memory cells that are thyristor-based, various embodiments of the invention have been found to be the particularly useful for high-speed, low-power memory cells in which a thin capacitively-coupled thyristor is used to provide a bi-stable storage element.
1. An electronic circuit arrangement comprising:
a thyristor having a current blocking state and a current passing state, the thyristor transitioning out of the current passing state during standby after a predetermined time interval;
a transistor having a first terminal coupled to the thyristor; and
a restore circuit adapted to periodically apply a pulse to the transistor, the pulse causing the transistor to provide a current path to the thyristor for preventing the transitioning during standby.
2. The electronic circuit arrangement of claim 1 , wherein the pulse is independent of the state of the thyristor.
3. The electronic circuit arrangement of claim 1 , wherein the pulse is controlled to track variations in a characteristic of the thyristor.
4. The electronic circuit arrangement of claim 3 , wherein the variation is temperature.
5. The electronic circuit arrangement of claim 1 , wherein the thyristor and the transistor form a memory cell.
6. The electronic circuit arrangement of claim 5 , wherein the transistor has a second terminal connecting to a bit line, and wherein the pulse is applied to the bit line.
7. The electronic circuit arrangement of claim 5 , wherein the transistor has a gate terminal connecting to a word line, and wherein the pulse is applied to the word line.
8. The electronic circuit arrangement of claim 1 , wherein the restore circuit comprises a circuit to control a frequency of the pulse.
9. The electronic circuit arrangement of claim 1 , wherein the restore circuit comprises a circuit to control amplitude of the pulse.
10. The electronic circuit arrangement of claim 1 , wherein the restore circuit comprises a circuit to control a width of the pulse.
11. An electronic circuit arrangement comprising:
a memory array comprising:
a plurality of memory cells,
a plurality of bit lines, and
a plurality of a word lines;
each memory cell of the plurality comprising:
a thyristor having a current blocking state and a current passing state, the thyristor transitioning out of the current passing state during standby after a predetermined time interval, and
a transistor having a first terminal coupled to the thyristor, a second terminal coupled to one of the bit lines, and a gate terminal coupled to one of the word lines; and
a restore circuit adapted to apply a pulse to the memory array;
at least one transistor of a memory cell of the plurality operable responsive to the pulse of the restore circuit to provide a current path to the thyristor for preventing the transitioning during standby.
12. The electronic circuit arrangement of claim 11 , wherein the pulse is independent of the state of the thyristor.
13. The electronic circuit arrangement of claim 11 , wherein the pulse is controlled to track variations in a characteristic of the thyristor.
14. The electronic circuit arrangement of claim 13 , wherein the variation is temperature.
15. The electronic circuit arrangement of claim 11 wherein the pulse is applied to the one bit line.
16. The electronic circuit arrangement of claim 11 , wherein the pulse is applied to the one word line.
17. The electronic circuit arrangement of claim 11 , wherein the restore circuit comprises a circuit to control a frequency of the pulse.
18. The electronic circuit arrangement of claim 11 , wherein the restore circuit comprises a circuit to control amplitude of the pulse.
19. The electronic circuit arrangement of claim 11 , wherein the restore circuit comprises a circuit to control a width of the pulse.