Circuit configuration for a current switch of a bit/word line of a MRAM device

• US 6,813,181 B1
• Filed: 05/27/2003
• Issued: 11/02/2004
• Est. Priority Date: 05/27/2003
• Status: Expired due to Fees

• Current Assignee: Infineon Technologies AG, International Business Machines Corporation
• Original Assignee: Infineon Technologies AG
• Inventors: DeBrosse, John K., Viehmann, Hans
• Primary Examiner(s): MAI, SON LUU
• Application Number:
  US10/445,550
• Time in Patent Office: 525 Days
• Field of Search: 365/158, 365/171, 365/173
• US Class Current: 365/158
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: G11C 7/12 Bit line control circuits, e.g. drivers, boosters, pull-up circuits, pull-down circuits, precharging circuits, equalising circuits, for bit lines
• CPC Class Codes: G11C 8/08 Word line control circuits, e.g. drivers, boosters, pull-up circuits, pull-down circuits, precharging circuits, for word lines

Abstract

A circuit configuration for a current switch of a bit line or a word line of a magnetoresistive random access memory (MRAM) device, comprising a directional switch and a voltage driver that, in operation, reduces the ON resistance of the directional switch. In one embodiment, each terminal of the line is provided with such a switch.

Claims

1. A circuit configuration for a current switch of a line, selected from one of a bit line and a word line, of a magnetoresistive random access memory (MRAM) device, comprising:

a bi-directional switch having a first input/output coupled to a first end of said line and a second input/output coupled to a current source, and a control input; and

a voltage driver maintaining said control input at a high voltage to decrease the ON resistance of the bi-directional switch.

2. The circuit configuration of claim 1 wherein the voltage driver comprises a pulse generator coupled to a control input of a transistor switch, said transistor switch having an input coupled to a controller of the MRAM device and an output coupled to the control input of the bi-directional switch.

3. The circuit configuration of claim 2 wherein the bi-directional switch and the transistor switch are field effect transistor switches.

4. The circuit configuration of claim 2 wherein the pulse generator produces a pulsed output voltage and a steady state output voltage that are greater than a threshold voltage of the transistor switch.

5. The circuit configuration of claim 4 wherein the pulsed output voltage increases a gate voltage of the bi-directional switch by at least a threshold voltage of the bi-directional switch.

6. The circuit configuration of claim 2 wherein a duration of a pulse of the pulse generator expires before said line is selected to transmit an electrical current.

7. A circuit configuration for writing an information content in a memory cell of a MRAM device, comprising:

(a) line, selected from one of a bit line and a word line, coupled to the memory cell of a plurality of such cells;

(b) a first driving circuit, comprising;

a first bi-directional switch having a first input/output coupled to a first end of said line and a second input/output coupled to a first current source, and a control input;

a first voltage driver coupled to the control input of the first bi-directional switch; and

a first sink transistor having an input coupled to a second input/output of the first bi-directional switch and an output coupled to a ground terminal of the line;

(c) a second driving circuit, comprising;

a second bi-directional switch having a first input/output coupled to a second end of said line and a second input/output coupled to a second current source, and a control input;

a second voltage driver coupled to the control input of the second bi-directional switch; and

a second sink transistor having an input coupled to a second input/output of the second bi-directional switch and an output coupled to the ground terminal of the line; and

(d) a controller controlling the first driving circuit and the second driving circuit.

8. The circuit configuration of claim 7 wherein each of said voltage drivers comprises a pulse generator coupled to a control input of a transistor switch, said switch having an input coupled to the controller and an output coupled to the control input of the first bi-directional switch.

9. The circuit configuration of claim 8 wherein the bi-directional switch and the transistor switch are field effect transistor switches.

10. The circuit configuration of claim 8 wherein the pulse generator produces a pulsed output voltage and a steady state output voltage that are greater than a threshold voltage of the transistor switch.

11. The circuit configuration of claim 10 wherein the pulsed output voltage increases a gate voltage of the bi-directional switch by at least a threshold voltage of the bi-directional switch.

12. The circuit configuration of claim 8 wherein a duration of a pulse of the pulse generator expires before said line is selected to transmit an electrical current.

13. The circuit configuration of claim 7 wherein the first current source is enabled and first sink transistor is set ON while the second current source is disabled and the second sink transistor is set OFF when said line transmits an electrical current from the first end to the second end of the line.

14. The circuit configuration of claim 7 wherein the first current source is disabled and first sink transistor is set OFF while the second current source is enabled and the second sink transistor is set ON when said line transmits an electrical current from the second end to the first end of the line.

15. A circuit configuration for a current switch of a line, selected from one of a bit line and a word line, of a magnetoresistive random access memory (MRAM) device, comprising:

an unidirectional switch having an output coupled to a first end of said line and an input coupled to a current source, and a control input; and

a voltage driver maintaining said control input at a high voltage to decrease the ON resistance of the unidirectional switch.

16. The circuit configuration of claim 15 wherein the voltage driver comprises a pulse generator coupled to a control input of a transistor switch, said transistor switch having an input coupled to a controller of the MRAM device and an output coupled to the control input of the unidirectional switch.

17. The circuit configuration of claim 16 wherein the transistor switch is field effect transistor switch.

18. The circuit configuration of claim 16 wherein the pulse generator produces a pulsed output voltage and a steady state output voltage that are greater than a threshold voltage of the transistor switch.

19. The circuit configuration of claim 18 wherein the pulsed output voltage increases a gate voltage of the unidirectional switch by at least a threshold voltage of the unidirectional switch.

20. The circuit configuration of claim 16 wherein a duration of a pulse of the pulse generator expires before said line is selected to transmit an electrical current.

21. A circuit configuration for writing an information content in a memory cell of a MRAM device, comprising:

(a) line, selected from one of a bit line and a word line, coupled to the memory cell of a plurality of such cells;

(b) a driving circuit, comprising;

a unidirectional switch having an output coupled to a first end of said line and an output coupled to a current source, and a control input;

a voltage driver coupled to the control input of the unidirectional switch; and

a sink transistor having an input coupled to a second end of said line and an output coupled to a ground terminal of the line; and

(c) a controller controlling the driving circuit.

22. The circuit configuration of claim 21 wherein the voltage driver comprises a pulse generator coupled to a control input of a transistor switch, said switch having an input coupled to the controller and an output coupled to the control input of the unidirectional switch.

23. The circuit configuration of claim 22 wherein the transistor switch is field effect transistor switch.

24. The circuit configuration of claim 22 wherein the pulse generator produces a pulsed output voltage and a steady state output voltage that are greater than a threshold voltage of the transistor switch.

25. The circuit configuration of claim 24 wherein the pulsed output voltage increases a gate voltage of the unidirectional switch by at least a threshold voltage of the unidirectional switch.

26. The circuit configuration of claim 22 wherein a duration of a pulse of the pulse generator expires before said line is selected to transmit an electrical current.

27. The circuit configuration of claim 21 wherein the current source is enabled and the sink transistor is set ON when said line transmits an electrical current.