Data restore in thryistor based memory devices
View Patent ↗In a thyristor based memory cell, one end of a reversed-biased diode is connected to the cathode of the thyristor. During standby, the second end of the diode is biased at a voltage that is higher than that at the cathode of the thyristor. During restore operation, the second end is pulled down to zero or even a negative value. If the cell is storing a “1,” the voltage at the thyristor cathode can be approximately 0.6 volt at the time of the pull down. The large forward-bias across the diode pulls down the thryistor cathode. This causes the thyristor to be restored. If the cell is storing a “0,” the voltage at the thyristor cathode can be approximately zero volt. The small or zero forward-bias across the diode is unable to disturb the “0” state. As a result, the memory cell is restored to its original state.
1. A memory arrangement comprising:
a first memory cell comprising a first thyristor having a cathode and a first access transistor having a first end connected to the cathode of the first thyristor;
a second memory cell comprising a second thyristor having a cathode and a second access transistor having a first end connected to the cathode of the second thyristor;
the second access transistor having a second end connected to a second end of the first access transistor;
a first diode having an anode and a cathode, the anode of the first diode being connected to the cathode of the first thyristor and the cathode of the first diode being at a first voltage level at a first time period and a second voltage level at a second time period, with the first voltage level being higher than the second voltage level; and
a second diode having an anode and a cathode, the anode of the second diode being connected to the cathode of the second thyristor and the cathode of the second diode being at substantially the first voltage level at the first time period and substantially the second voltage level at the second time period.
2. The memory arrangement of claim 1 wherein the second voltage level is equal to approximately zero volt.
3. The memory arrangement of claim 1 wherein the second voltage level has a negative value.
4. The memory arrangement of claim 1 wherein the first time period has a duration that is longer than that of the second time period.
5. The memory arrangement of claim 1 wherein each of the first and the second thyristors has a current blocking and a current-conducting state, and the first and the second thyristors perform an internal positive feedback operation during the second time period while in one of the states.
6. The memory arrangement of claim 1 wherein at least one of the first and the second thyristors comprises a control gate capacitively coupled to a thyristor body.
7. The memory arrangement of claim 6 wherein the at least one thyristor is a thin capacitively coupled thyristor.
8. The arrangement of claim 1 wherein the cathodes of the first and the second diodes are connected together.
9. The memory arrangement of claim 8 wherein the second voltage level is equal to approximately zero volt.
10. The memory arrangement of claim 8 wherein the second voltage level has a negative value.
11. The memory arrangement of claim 8 wherein the first time period has a duration that is longer than that of the second time period.
12. The memory arrangement of claim 8 wherein each of the first and the second thyristors has a current blocking and a current-conducting state, and the first and the second thyristors perform an internal positive feedback operation during the second time period while in one of the states.
13. The memory arrangement of claim 8 wherein at least one of the first and the second thyristors comprises a control gate capacitively coupled to a thyristor body.
14. The memory arrangement of claim 13 wherein the at least one thyristor is a thin capacitively coupled thyristor.