System and method of adjusting a resistance-based memory circuit parameter

• US 8,423,329 B2
• Filed: 01/21/2010
• Issued: 04/16/2013
• Est. Priority Date: 01/21/2010
• Status: Active Grant

• Current Assignee: Industry Academic Cooperation Foundation, Qualcomm, Inc.
• Original Assignee: Industry-Academic Cooperation Foundation Yonsei University, Qualcomm, Inc.
• Inventors: Jung, Seong-Ook, Kim, Jisu, Kang, Seung H., Song, Jee-Hwan
• Primary Examiner(s): PHAN, THAI Q
• Application Number:
  US12/691,415
• Publication Number:
  US 20110178768A1
• Time in Patent Office: 1,181 Days
• Field of Search: 703/2, 703/13, 703/18, 365/148, 365/226, 365/189.09
• US Class Current: 703/2
• CPC Class Codes: G06F 2111/08 Probabilistic or stochastic CAD
• CPC Class Codes: G06F 30/367 Design verification, e.g. using simulation, simulation program with integrated circuit emphasis [SPICE], direct methods or relaxation methods
• CPC Class Codes: G11C 11/1673 Reading or sensing circuits or methods
• CPC Class Codes: G11C 7/02 with means for avoiding parasitic signals
• CPC Class Codes: G11C 7/06 Sense amplifiers; Associated circuits , e.g. timing or triggering circuits

Abstract

Systems and methods of resistance-based memory circuit parameter adjustment are disclosed. In a particular embodiment, a method of determining a set of parameters of a resistance-based memory circuit includes determining a range of sizes for a clamp transistor and selecting a set of clamp transistors having sizes within the determined range of sizes. For each clamp transistor in the set of clamp transistors, a simulation may be executed to generate a first contour graph representing current values over a range of statistical values. The first contour graph may be used to identify a read disturbance area and a design range of the gate voltage of the clamp transistor and a load of the clamp transistor. The method may execute a simulation to generate a second contour graph representing sense margin over a range of statistical values of the gate voltage of the clamp transistor and the load of the clamp transistor. A sense margin may be selected based on the second contour graph that also satisfies the design range of the first contour graph. A sense margin may be determined for a selected clamp transistor in the set of transistors and the corresponding gate voltage and the load of the selected clamp transistor is determined based on the determined sense margin.

Claims

1. A method of determining a set of circuit parameters, the method comprising:

determining a range of sizes for a clamp transistor and selecting a set of clamp transistors each having a size within the determined range of sizes;

for each clamp transistor in the set of clamp transistors;

executing a first simulation to generate a first contour graph representing current data over a range of statistical values, the first contour graph identifying a read disturbance area and a design range of a gate voltage of the clamp transistor and a load of the clamp transistor;

executing a second simulation to generate a second contour graph representing a sense margin over a range of statistical values of the gate voltage of the clamp transistor and the load of the clamp transistor;

selecting a first sense margin based on the second contour graph and that satisfies the design range of the first contour graph; and

determining a second sense margin corresponding to a selected clamp transistor in the set of clamp transistors and selecting a corresponding gate voltage and a corresponding load of the selected clamp transistor based on the second sense margin.

2. The method of claim 1, wherein the selected clamp transistor is within a circuit path that includes a resistance-based memory cell.

3. The method of claim 2, wherein the resistance-based memory cell includes a magnetic tunnel junction (MTJ) device.

4. The method of claim 2, wherein the circuit path includes a load transistor.

5. The method of claim 4, wherein the corresponding load of the selected clamp transistor corresponds to a selected width of the load transistor.

6. The method of claim 1, wherein the first simulation is a Monte Carlo simulation.

7. The method of claim 1, wherein the first sense margin is a largest sense margin within the design range of the first contour graph.

8. The method of claim 1, wherein the selected clamp transistor comprises a component of a memory circuit that includes a magnetoresistive random access memory (MRAM), a phase-change random access memory (PRAM), or a spin torque transfer MRAM (STT-MRAM).

9. The method of claim 1, wherein executing the first simulation to generate the first contour graph, executing the second simulation to generate the second contour graph, selecting the first sense margin, determining the second sense margin, and selecting the corresponding gate voltage are executed at a processor integrated into an electronic device.

10. A method of determining a set of circuit parameters, the method comprising:

determining a range of sizes for a clamp transistor and selecting a set of clamp transistors each having a size within the determined range of sizes;

for each clamp transistor in the set of clamp transistors;

executing a first simulation to generate a first set of results representing current values over a first statistical range, the first set of results identifying a read disturbance range and a valid operating range of a gate voltage of the clamp transistor and a load of the clamp transistor;

executing a second simulation to generate a second set of results representing a sense margin over a second statistical range and to identify values of the gate voltage of the clamp transistor and the load of the clamp transistor;

selecting a particular sense margin above a sense margin threshold based on the second set of results and that satisfies the valid operating range of the first set of results;

selecting a design sense margin of a sense amplifier, the design sense margin corresponding to a selected clamp transistor in the set of transistors based on the first set of results and based on the second set of results; and

selecting a particular gate voltage of the selected clamp transistor and a size of a load transistor based on the selected design sense margin.

11. The method of claim 10, wherein the load transistor is a p-type metal oxide semiconductor field effect (PMOS) transistor and the selected clamp transistor is an n-type metal oxide semiconductor field effect (NMOS) transistor.

12. The method of claim 10, wherein the sense amplifier is a first sense amplifier that provides an output to a second sense amplifier.

13. The method of claim 10, wherein the selected clamp transistor is responsive to a resistance-based memory cell.

14. The method of claim 13, wherein the resistance-based memory cell is a memory cell of a magnetoresistive random access memory (MRAM).

15. The method of claim 13, wherein the resistance-based memory cell is a memory cell of a phase-change random access memory (PRAM).

16. The method of claim 13, wherein the resistance-based memory cell is a memory cell of a spin transfer torque-magnetoresistive random access memory (STT-MRAM).

17. A sense amplifier circuit comprising:

a p-type metal oxide semiconductor field effect (PMOS) transistor; and

an n-type metal oxide semiconductor field effect (NMOS) transistor;

wherein a size of the PMOS transistor and a gate voltage of the NMOS transistor are determined by;

determining a range of sizes for the NMOS transistor and selecting a set of NMOS transistors having sizes within the determined range of sizes;

for each transistor in the set of NMOS transistors;

executing a first simulation to generate a first set of results representing current values over a first statistical range, the first set of results identifying a read disturbance range and a valid operating range of the gate voltage of the NMOS transistor and a load of the NMOS transistor;

executing a second simulation to generate a second set of results representing a sense margin of a sense amplifier over a second statistical range and to identify values of the gate voltage of the NMOS transistor and the load of the NMOS transistor;

selecting a particular sense margin of the sense amplifier that is above a sense margin threshold based on the second set of results and that is within the valid operating range of the first set of results;

selecting a design sense margin for one transistor in the set of NMOS transistors based on the first set of results and based on the second set of results; and

selecting the gate voltage of the NMOS transistor and the size of the PMOS transistor based on the selected design sense margin.

18. The sense amplifier circuit of claim 17, further comprising a resistance-based memory cell within a circuit path that includes the NMOS transistor and the PMOS transistor.

19. The sense amplifier circuit of claim 18, wherein the resistance-based memory cell includes a cell of a magnetoresistive random access memory (MRAM) device.

20. The sense amplifier circuit of claim 18, wherein the resistance-based memory cell includes a magnetic tunnel junction (MTJ) device.

21. The sense amplifier circuit of claim 17, wherein the sense amplifier is a first sense amplifier that provides an output to a second sense amplifier, and wherein the first sense amplifier is responsive to a resistance presented by a memory cell of a resistance-based memory.

22. The sense amplifier circuit of claim 17, wherein the first simulation is a Monte Carlo type simulation.

23. A processor readable medium having processor instructions that are executable to cause a processor to:

determine a range of sizes for a clamp transistor and selecting a set of clamp transistors having sizes within the determined range of sizes;

for each clamp transistor in the set of clamp transistors;

execute a first simulation to generate a first set of results representing current values over a first statistical range, the first set of results identifying a read disturbance range and a valid operating range of a gate voltage of the clamp transistor and a load of the clamp transistor;

execute a second simulation to generate a second set of results representing a sense margin over a second statistical range and to identify values of the gate voltage of the clamp transistor and the load of the clamp transistor;

select a particular sense margin above a sense margin threshold based on the second set of results and that satisfies the valid operating range of the first set of results;

selecting a design sense margin of a sense amplifier, the design sense margin corresponding to a selected clamp transistor in the set of transistors based on the first set of results and based on the second set of results; and

selecting the gate voltage of the selected clamp transistor and a size of a load transistor based on the selected design sense margin.

24. The processor readable medium of claim 23, wherein the processor instructions are further executable to cause the processor to output a data file that represents a circuit design of a resistance-based memory circuit having the design sense margin.

25. The processor readable medium of claim 23, wherein the processor instructions are compatible with a computer-aided design tool.

26. An apparatus comprising:

means for determining a range of sizes for a clamp transistor and selecting a set of clamp transistors having sizes within the determined range of sizes;

for each clamp transistor in the set of clamp transistors;

means for executing a first simulation to generate a first set of results representing current values over a first statistical range, the first set of results identifying a read disturbance range and a valid operating range of a gate voltage of the clamp transistor and a load of the clamp transistor;

means for executing a second simulation to generate a second set of results representing a sense margin over a second statistical range and to identify values of the gate voltage of the clamp transistor and the load of the clamp transistor;

means for selecting a particular sense margin above a sense margin threshold based on the second set of results and that satisfies the valid operating range of the first set of results;

means for selecting a design sense margin of a sense amplifier, the design sense margin corresponding to a selected clamp transistor in the set of transistors based on the first set of results and based on the second set of results; and

means for selecting a corresponding gate voltage of the selected clamp transistor and a size of a load transistor based on the selected design sense margin.

27. The apparatus of claim 26, wherein the selected clamp transistor is integrated in at least one semiconductor die.

28. The apparatus of claim 27, further comprising a device including a set top box, a music player, a video player, an entertainment unit, a navigation device, a communications device, a personal digital assistant (PDA), a fixed location data unit, a computer, or a combination thereof into which the at least one semiconductor die is integrated.

29. A method comprising:

receiving design information representing at least one physical property of a semiconductor device, the semiconductor device including;

a load transistor; and

a clamp transistor;

wherein a size of the load transistor and a gate voltage of the clamp transistor are determined by;

determining a range of sizes for the clamp transistor and selecting a set of clamp transistors having sizes within the range of sizes;

for each transistor in the set of clamp transistors;

executing a first simulation to generate a first set of results representing current values over a first statistical range, the first set of results identifying a read disturbance range and a valid operating range of the gate voltage of the clamp transistor and a load of the clamp transistor;

executing a second simulation to generate a second set of results representing a sense margin of a sense amplifier over a second statistical range and to identify values of the gate voltage of the clamp transistor and the load of the clamp transistor;

selecting a particular sense margin of the sense amplifier that is above a sense margin threshold based on the second set of results and that is within the valid operating range of the first set of results;

selecting a design sense margin for one clamp transistor of the set of clamp transistors based on the first set of results and based on the second set of results; and

selecting the gate voltage of the clamp transistor and the size of the load transistor based on the selected design sense margin;

transforming the design information to comply with a file format; and

generating a data file including the transformed design information.

30. The method of claim 29, wherein the data file includes a GDSII format.

31. A method comprising:

receiving a data file including design information including physical positioning information of a packaged semiconductor device on a circuit board; and

manufacturing the circuit board configured to receive the packaged semiconductor device according to the design information, wherein the packaged semiconductor device comprises;

a load transistor; and

a clamp transistor;

wherein a size of the load transistor and a gate voltage of the clamp transistor are determined by;

determining a range of sizes for the clamp transistor and selecting a set of clamp transistors having sizes within the range of sizes;

for each transistor in the set of clamp transistors;

executing a first simulation to generate a first set of results representing current values over a first statistical range, the first set of results identifying a read disturbance range and a valid operating range of the gate voltage of the clamp transistor and a load of the clamp transistor;

executing a second simulation to generate a second set of results representing a sense margin of a sense amplifier over a second statistical range and to identify values of the gate voltage of the clamp transistor and the load of the clamp transistor;

selecting a particular sense margin of the sense amplifier that is above a sense margin threshold based on the second set of results and that is within the valid operating range of the first set of results;

selecting a design sense margin for one clamp transistor of the set of clamp transistors based on the first set of results and based on the second set of results; and

selecting the gate voltage of the clamp transistor and the size of the load transistor based on the selected design sense margin.

32. The method of claim 31, wherein the data file has a GERBER format.

33. The method of claim 31, further comprising integrating the circuit board into a device that includes a set top box, a music player, a video player, an entertainment unit, a navigation device, a communications device, a personal digital assistant (PDA), a fixed location data unit, a computer, or a combination thereof.