Device and method for regulating the threshold voltage of a transistor

• US 20070008796A1
• Filed: 06/28/2006
• Published: 01/11/2007
• Est. Priority Date: 06/29/2005
• Status: Active Grant

• Current Assignee: Polaris Innovations Limited (Wi-LAN Inc.)
• Original Assignee: Qimonda AG (Infineon Technologies AG)
• Inventors: Egerer, Jens, Bartenschlager, Rainer, Schneider, Helmut
• Granted Patent: US 7,425,861 B2
• Time in Patent Office: Days
• US Class Current: 365/211
• CPC Class Codes: G11C 7/04 with means for avoiding disturbances due to temperature effects
• CPC Class Codes: G11C 7/06 Sense amplifiers; Associated circuits , e.g. timing or triggering circuits
• CPC Class Codes: G11C 7/08 Control thereof

Abstract

A method and a device for regulating the threshold voltage of a transistor is disclosed. The device includes a circuit configured for modifying a voltage applied at a bulk connection of the transistor such that the threshold voltage of the transistor is substantially temperature-independent at least in a first temperature range. In one embodiment, the device includes a memory device, and the transistor is a transistor of a sense amplifier of the memory device.

Claims

1. A device for regulating the threshold value of a transistor, comprising:

a circuit to modify a voltage applied at a bulk connection of the transistor.

2. The device according to claim 1, wherein the circuit is configured such that, by modifying the voltage applied at the bulk connection of the transistor, the threshold voltage of the transistor is temperature-independent at least in a first temperature range.

3. The device according to claim 1, wherein the circuit comprises a transistor that is connected as a diode.

4. The device according to claim 1, wherein the circuit comprises a comparator.

5. The device according to claim 4, wherein the means comprises a charge pump controlled by the comparator.

6. The device according to claim 4, wherein the comparator is configured such that it compares a gate source voltage of the transistor that is connected as a diode with a reference voltage.

7. The device according to claim 6, wherein the comparator is configured such that, depending on the result of the comparison of the gate source voltage with the reference voltage, the charge pump is activated or deactivated.

8. The device according to claim 5, wherein a voltage applied at a bulk connection of the transistor that is connected as a diode is modified by the charge pump.

9. The device according to claim 8, wherein the voltage applied at the bulk connection of the transistor is modified simultaneously by the charge pump.

10. The device according to claim 9, wherein the threshold voltage of the transistor remains temperature-dependent in a second temperature range.

11. The device according to claim 1, wherein the transistor is a field effect transistor.

12. The device according to claim 1, wherein the transistor is a transistor of a sense amplifier of a semiconductor memory device.

13. The device according to claim 3, wherein the transistor that is connected as a diode is a field effect transistor.

14. The device according to claim 1, wherein the circuit comprises a transistor at the gate connection of which there is present a constant voltage.

15. The device according to claim 14, wherein the intensity of the constant voltage corresponds approximately to the desired intensity of the threshold voltage.

16. The device according to claim 14, wherein the circuit comprises a comparator that is configured such that it compares a drain source voltage of the transistor at the gate connection of which there is present the constant voltage with a reference voltage.

17. A method for regulating the threshold voltage of a transistor, the method comprises:

modifying the voltage applied at a bulk connection of the transistor such that the threshold voltage of the transistor is substantially temperature-independent at least in a first temperature range.

18. The method according to claim 17, the method additionally comprising:

comparing a gate source voltage of a transistor that is connected as a diode with a reference voltage (fb_ref).

19. The method according to claim 18, the method additionally comprising:

activating or deactivating a charge pump, depending on the result of the comparison of the gate source voltage with the reference voltage.

20. The method according to claim 19, the method additionally comprising:

modifying a voltage applied at a bulk connection of the transistor that is connected as a diode by the charge pump.

21. The method according to claim 20, wherein the voltage applied at the bulk connection of the transistor is simultaneously modified by the charge pump.

22. The method according to claim 21, wherein, for regulating the threshold voltage of a further transistor, the charge pump simultaneously modifies a voltage applied at a bulk connection of the further transistor.

23. A device comprising:

a transistor; and

means for modifying a voltage applied at a bulk connection of the transistor for regulating the threshold value of a transistor.

24. The device according to claim 23, wherein the means is configured such that, by modifying the voltage applied at the bulk connection of the transistor, the threshold voltage of the transistor is temperature-independent at least in a first temperature range.

25. The device according to claim 24, wherein the means comprises a transistor that is connected as a diode.

26. The device according to claim 23, wherein the means comprises a comparator.

27. The device according to claim 24, wherein the means comprises a charge pump controlled by the comparator, wherein the comparator is configured such that it compares a gate source voltage of the transistor that is connected as a diode with a reference voltage, and, wherein the comparator is configured such that, depending on the result of the comparison of the gate source voltage with the reference voltage, the charge pump is activated or deactivated.

28. The device according to claim 23, wherein a voltage applied at a bulk connection of the transistor that is connected as a diode is modified by the charge pump.

29. A comprising:

a semiconductor memory device having a sense amplifier including a transistor; and

a circuit to modify a voltage applied at a bulk connection of the transistor.