System and method for negative word line driver circuit

• US 6,809,986 B2
• Filed: 08/29/2002
• Issued: 10/26/2004
• Est. Priority Date: 08/29/2002
• Status: Active Grant

• Current Assignee: Nanya Technology Corporation
• Original Assignee: Micron Technology, Inc.
• Inventors: Blodgett, Greg, Vo, Huy, Kim, Tae Hyoung
• Primary Examiner(s): Lebentritt, Michael S.
• Assistant Examiner(s): Luu, Pho M.
• Application Number:
  US10/232,953
• Publication Number:
  US 20040042322A1
• Time in Patent Office: 789 Days
• Field of Search: 365/230.06, 365/191, 365/226, 365/189.07, 365/189.01, 365/189.09
• US Class Current: 365/230.06
• 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 negative word line driver employs devices to maintain the potential difference between the active word line signal and the inactive word line signal while reducing the need for a significant negative voltage supply. One form of the negative word line driver employs an isolation element to couple the word line to ground when the inputs to the word line driver indicate the word line should not be active, while the word line is also coupled to the negative voltage supply. Another form of the form of the negative word line driver receives as inputs the voltages to be driven on the word line and can be implemented with fewer transistors but still allows the word line to be driven at a negative voltage with a reduced negative voltage supply.

Claims

1. A word line driver system for developing a voltage on a word line, the word line driver circuit comprising:

a first coupling circuit coupled to the word line and adapted to receive a control input signal and having a first terminal adapted to receive a first reference voltage source, the first coupling circuit operable responsive to the control input signal being active to couple the word line to the first terminal; and

a second coupling circuit coupled to the word line and adapted to receive the control input signal, and having first and second terminals adapted to receive second and third reference voltage sources, respectively, the second coupling circuit operable responsive to the control input signal being inactive to couple the word line through an isolation element to the first terminal and operable to couple the word line to the second terminal.

2. The system of claim 1 wherein the second coupling circuit first couples the word line through the isolation element to the first terminal and thereafter couples the word line to the second terminal.

3. The system of claim 1 wherein the first reference voltage comprises an active word line voltage.

4. The system of claim 3 wherein the active word line voltage comprises a positive voltage.

5. The system of claim 1 wherein the lesser of the second reference voltage and the third reference voltage comprises an inactive word line voltage.

6. The system of claim 5 wherein the second reference voltage comprises ground.

7. The system of claim 5 wherein the third reference voltage comprises a negative voltage.

8. The system of claim 1 wherein the isolation element comprises a transistor.

9. The system of claim 1 wherein the isolation element comprises a diode-coupled transistor.

10. The system of claim 1 wherein the isolation element comprises a diode.

11. The system of claim 1 wherein second coupling circuit comprises a coupling transistor having a control input coupled to receive the control input signal and coupled in series with the isolation element between the word line and the second reference voltage source.

12. The system of claim 11 wherein the isolation element is coupled between the coupling transistor and the second reference voltage source.

13. The system of claim 11 wherein the isolation element is coupled between the word line and the coupling transistor.

14. A word line driver system, the word line driver system generating a high word line voltage or a low word line voltage on a word line, the word line driver system comprising:

a system low voltage source;

a word line low voltage source;

a word line high voltage source;

a plurality of control inputs, a word line high combination of the control inputs signaling the high word line voltage should be generated and a word low combination of the control inputs signaling the low word line voltage should be generated;

a word line high coupling system receiving the control inputs and the word line high voltage source, the word line high coupling system coupling the word line high voltage source to the word line only upon the word line high combination of control inputs being received; and

a word line low coupling system receiving the control inputs, the system low voltage source, and the word line low voltage source, the word line low coupling system coupling the word line to both the system low voltage source and the word line low voltage source only upon the word line low combination of control inputs being received.

15. The system of claim 14 wherein the word line low voltage source comprises a negative voltage source.

16. The system of claim 14 wherein the system low voltage source comprises a ground voltage source.

17. The system of claim 14 wherein the word line high voltage source supplies a voltage greater than a maximum voltage of the control inputs.

18. The system of claim 14 wherein the word line low coupling system comprises at least one transistor selectively coupling the system low voltage source to the word line.

19. The system of claim 14 wherein the word line low coupling system comprises at least one transistor selectively coupling the word line low voltage source to the word line.

20. The system of claim 14 wherein the word line low coupling system further comprises an isolation element, the isolation element preventing current from flowing from a higher of voltages carried by the word line low voltage source and the system low voltage source to the lower of the word line low voltage source and the system voltage.

21. The system of claim 20 wherein the isolation element comprises a transistor.

22. The system of claim 20 wherein the isolation element comprises a diode-coupled transistor.

23. The system of claim 20 wherein the isolation element comprises a diode.

24. The system of claim 20 wherein the isolation element comprises an externally controlled transistor coupled to an external isolation input, the external isolation input disabling the externally controlled transistor preventing current from flowing from the higher of the voltages carried by the word line low voltage source and the system low voltage source to the lower of the word line low voltage source and the system low voltage source.

25. The system of claim 14 wherein the word line driver system comprises a translator circuit comprising a pair of cross coupled transistors so the word line high voltage is greater than the voltage of the control inputs.

26. The system of claim 25 wherein the pair of cross coupled transistors comprise a pair of PMOS transistors.

27. The system of claim 14 wherein the word line high coupling system comprises a PMOS transistor coupling the word line high voltage source to the word line.

28. A memory system comprising:

a memory controller;

a memory bus operably coupled with the memory controller to communicate memory commands from the memory controller and communicate memory output signals to the memory controller;

a plurality of DRAM devices comprising a plurality of memory cells, the memory cells being disposed in rows and columns; and

an addressing system operably connected to the DRAM devices, the addressing system responsive to an address signal by accessing a row and a column in the DRAM devices corresponding to the row address signal by generating a plurality of control inputs to the DRAM devices, a word line high combination of the control inputs signaling the high word line voltage should be generated and a word low combination of the control inputs signaling the low word line voltage should be generated; and

a word line driver system for developing a voltage on a word line, the word line driver circuit comprising;

a first coupling circuit coupled to the word line and adapted to receive a control input signal and having a first terminal adapted to receive a first reference voltage source, the first coupling circuit operable responsive to the control input signal being active to couple the word line to the first terminal; and

a second coupling circuit coupled to the word line and adapted to receive the control input signal, and having first and second terminals adapted to receive second and third reference voltage sources, respectively, the second coupling circuit operable responsive to the control input signal being inactive to couple the word line through an isolation element to the first terminal and operable to couple the word line to the second terminal.

29. The memory system of claim 28 wherein the second coupling circuit first couples the word line through the isolation element to the first terminal and thereafter couples the word line to the second terminal.

30. The memory system of claim 28 wherein the first reference voltage comprises an active word line voltage.

31. The memory system of claim 30 wherein the active word line voltage comprises a positive voltage.

32. The memory system of claim 28 wherein the lesser of the second reference voltage and the third reference voltage comprises an inactive word line voltage.

33. The memory system of claim 32 wherein the second reference voltage comprises ground.

34. The memory system of claim 32 wherein the third reference voltage comprises a negative voltage.

35. The memory system of claim 28 wherein the isolation element comprises a transistor.

36. The memory system of claim 28 wherein the isolation element comprises a diode-coupled transistor.

37. The memory system of claim 28 wherein the isolation element comprises a diode.

38. The memory system of claim 28 wherein second coupling circuit comprises a coupling transistor having a control input coupled to receive the control input signal and coupled in series with the isolation element between the word line and the second reference voltage source.

39. The memory system of claim 38 wherein the isolation element is coupled between the coupling transistor and the second reference voltage source.

40. The memory system of claim 38 wherein the isolation element is coupled between the word line and the coupling transistor.

41. A memory system comprising:

a memory controller;

a memory bus operably coupled with the memory controller to communicate memory commands from the memory controller and communicate memory output signals to the memory controller;

a plurality of DRAM devices comprising a plurality of memory cells, the memory cells being disposed in rows and columns; and

an addressing system operably connected to the DRAM devices, the addressing system responsive to an address signal by accessing a row and a column in the DRAM devices corresponding to the row address signal by generating a plurality of control inputs to the DRAM devices, a word line high combination of the control inputs signaling the high word line voltage should be generated and a word low combination of the control inputs signaling the low word line voltage should be generated; and

a word line driver system, the word line driver system generating a high word line voltage or a low word line voltage on a word line, the word line driver system comprising;

a system low voltage source;

a word line low voltage source;

a word line high voltage source;

a plurality of control inputs, a word line high combination of the control inputs signaling the high word line voltage should be generated and a word low combination of the control inputs signaling the low word line voltage should be generated;

a word line high coupling system receiving the control inputs and the word line high voltage source, the word line high coupling system coupling the word line high voltage source to the word line only upon the word line high combination of control inputs being received; and

a word line low coupling system receiving the control inputs, the system low voltage source, and the word line low voltage source, the word line low coupling system coupling the word line to both the system low voltage source and the word line low voltage source only upon the word line low combination of control inputs being received.

42. The memory system of claim 41 wherein the word line low voltage source comprises a negative voltage source.

43. The memory system of claim 41 wherein the system low voltage source comprises a ground voltage source.

44. The memory system of claim 41 wherein the word line high voltage source supplies a voltage greater than a maximum voltage of the control inputs.

45. The memory system of claim 41 wherein the word line low coupling system comprises at least one transistor selectively coupling the system low voltage source to the word line.

46. The memory system of claim 41 wherein the word line low coupling system comprises at least one transistor selectively coupling the word line low voltage source to the word line.

47. The memory system of claim 41 wherein the word line low coupling system further comprises an isolation element, the isolation element preventing current from flowing from a higher of voltages carried by the word line low voltage source and the system low voltage source to the lower of the word line low voltage source and the system voltage.

48. The memory system of claim 47 wherein the isolation element comprises a transistor.

49. The memory system of claim 47 wherein the isolation element comprises a diode-coupled transistor.

50. The memory system of claim 47 wherein the isolation element comprises a diode.

51. The memory system of claim 47 wherein the isolation element comprises an externally controlled transistor coupled to an external isolation input, the external isolation input disabling the externally controlled transistor preventing current from flowing from the higher of the voltages carried by the word line low voltage source and the system low voltage source to the lower of the word line low voltage source and the system low voltage source.

52. The memory system of claim 41 wherein the word line driver system comprises a translator circuit comprising a pair of cross coupled transistors so the word line high voltage is greater than the voltage of the control inputs.

53. The memory system of claim 52 wherein the pair of cross coupled transistors comprise a pair of PMOS transistors.

54. The memory system of claim 41 wherein the word line high coupling system comprises a PMOS transistor coupling the word line high voltage source to the word line.

55. A computer system, comprising:

a processor;

an input device, operably connected to the processor, allowing data to be entered into the computer system;

an output device, operably connected to the processor, allowing data to be output from the computer system; and

a memory system comprising;

a memory controller;

a memory bus operably coupled with the memory controller to communicate memory commands from the memory controller and communicate memory output signals to the memory controller;

a plurality of DRAM devices comprising a plurality of memory cells, the memory cells being disposed in rows and columns; and

an addressing system operably connected to the DRAM devices, the addressing system responsive to an address signal by accessing a row and a column in the DRAM devices corresponding to the row address signal by generating a plurality of control inputs to the DRAM devices, a word line high combination of the control inputs signaling the high word line voltage should be generated and a word low combination of the control inputs signaling the low word line voltage should be generated; and

a word line driver system for developing a voltage on a word line, the word line driver circuit comprising;

a first coupling circuit coupled to the word line and adapted to receive a control input signal and having a first terminal adapted to receive a first reference voltage source, the first coupling circuit operable responsive to the control input signal being active to couple the word line to the first terminal; and

a second coupling circuit coupled to the word line and adapted to receive the control input signal, and having first and second terminals adapted to receive second and third reference voltage sources, respectively, the second coupling circuit operable responsive to the control input signal being inactive to couple the word line through an isolation element to the first terminal and operable to couple the word line to the second terminal.

56. The computer system of claim 55 wherein the second coupling circuit first couples the word line through the isolation element to the first terminal and thereafter couples the word line to the second terminal.

57. The computer system of claim 55 wherein the first reference voltage comprises an active word line voltage.

58. The computer system of claim 57 wherein the active word line voltage comprises a positive voltage.

59. The computer system of claim 55 wherein the lesser of the second reference voltage and the third reference voltage comprises an inactive word line voltage.

60. The computer system of claim 59 wherein the second reference voltage comprises ground.

61. The computer system of claim 59 wherein the third reference voltage comprises a negative voltage.

62. The computer system of claim 55 wherein the isolation element comprises a transistor.

63. The computer system of claim 55 wherein the isolation element comprises a diode-coupled transistor.

64. The computer system of claim 55 wherein the isolation element comprises a diode.

65. The computer system of claim 55 wherein second coupling circuit comprises a coupling transistor having a control input coupled to receive the control input signal and coupled in series with the isolation element between the word line and the second reference voltage source.

66. The computer system of claim 65 wherein the isolation element is coupled between the coupling transistor and the second reference voltage source.

67. The computer system of claim 65 wherein the isolation element is coupled between the word line and the coupling transistor.

68. A computer system, comprising:

a processor;

an input device, operably connected to the processor, allowing data to be entered into the computer system;

an output device, operably connected to the processor, allowing data to be output from the computer system; and

a memory system comprising;

a memory controller;

a memory bus operably coupled with the memory controller to communicate memory commands from the memory controller and communicate memory output signals to the memory controller;

a plurality of DRAM devices comprising a plurality of memory cells, the memory cells being disposed in rows and columns; and

an addressing system operably connected to the DRAM devices, the addressing system responsive to an address signal by accessing a row and a column in the DRAM devices corresponding to the row address signal by generating a plurality of control inputs to the DRAM devices, a word line high combination of the control inputs signaling the high word line voltage should be generated and a word low combination of the control inputs signaling the low word line voltage should be generated; and

a word line driver system, the word line driver system generating a high word line voltage or a low word line voltage on a word line, the word line driver system comprising;

a system low voltage source;

a word line low voltage source;

a word line high voltage source;

a plurality of control inputs, a word line high combination of the control inputs signaling the high word line voltage should be generated and a word low combination of the control inputs signaling the low word line voltage should be generated;

a word line high coupling system receiving the control inputs and the word line high voltage source, the word line high coupling system coupling the word line high voltage source to the word line only upon the word line high combination of control inputs being received; and

a word line low coupling system receiving the control inputs, the system low voltage source, and the word line low voltage source, the word line low coupling system coupling the word line to both the system low voltage source and the word line low voltage source only upon the word line low combination of control inputs being received.

69. The computer system of claim 68 wherein the word line low voltage source comprises a negative voltage source.

70. The computer system of claim 68 wherein the system low voltage source comprises a ground voltage source.

71. The computer system of claim 68 wherein the word line high voltage source supplies a voltage greater than a maximum voltage of the control inputs.

72. The computer system of claim 68 wherein the word line low coupling system comprises at least one transistor selectively coupling the system low voltage source to the word line.

73. The computer system of claim 68 wherein the word line low coupling system comprises at least one transistor selectively coupling the word line low voltage source to the word line.

74. The computer system of claim 68 wherein the word line low coupling system further comprises an isolation element, the isolation element preventing current from flowing from a higher of voltages carried by the word line low voltage source and the system low voltage source to the lower of the word line low voltage source and the system voltage.

75. The computer system of claim 74 wherein the isolation element comprises a transistor.

76. The computer system of claim 74 wherein the isolation element comprises a diode-coupled transistor.

77. The computer system of claim 74 wherein the isolation element comprises a diode.

78. The computer system of claim 74 wherein the isolation element comprises an externally controlled transistor coupled to an external isolation input, the external isolation input disabling the externally controlled transistor preventing current from flowing from the higher of the voltages carried by the word line low voltage source and the system low voltage source to the lower of the word line low voltage source and the system low voltage source.

79. The computer system of claim 68 wherein the word line driver system comprises a translator circuit comprising a pair of cross coupled transistors so the word line high voltage is greater than the voltage of the control inputs.

80. The computer system of claim 79 wherein the pair of cross coupled transistors comprise a pair of PMOS transistors.

81. The computer system of claim 68 wherein the word line high coupling system comprises a PMOS transistor coupling the word line high voltage source to the word line.

82. A method of developing a voltage on a word line, comprising:

selectively coupling a first reference voltage source to the word line responsive to a control input signal being active;

selectively coupling a second and third reference voltage source to the word line responsive to the control signal being inactive;

coupling the second reference voltage to the word line through an isolation element so that current will not flow from the higher of the second or the third reference voltage source to the lower of the second or the third voltage source.

83. The method of claim 82 further comprising first coupling the word line to the second reference voltage and thereafter coupling the word line to the third reference voltage.

84. The method of claim 82 wherein the first reference voltage comprises an active word line voltage.

85. The method of claim 84 wherein the active word line voltage comprises a positive voltage.

86. The method of claim 82 wherein the lesser of the second reference voltage and the third reference voltage comprises an inactive word line voltage.

87. The method of claim 86 wherein the second reference voltage comprises ground.

88. The method of claim 86 wherein the third reference voltage comprises a negative voltage.

89. The method of claim 82 wherein the isolation element comprises a transistor.

90. The method of claim 82 wherein the isolation element comprises a diode-coupled transistor.

91. The method of claim 82 wherein the isolation element comprises a diode.

92. The method of claim 82 wherein second coupling circuit comprises a coupling transistor having a control input coupled to receive the control input signal and coupled in series with the isolation element between the word line and the second reference voltage source.

93. The method of claim 92 wherein the isolation element is coupled between the coupling transistor and the second reference voltage source.

94. The method of claim 92 wherein the isolation element is coupled between the word line and the coupling transistor.

95. A method of driving a word line by generating a high word line voltage or a low word line voltage on the word line, the method comprising:

receiving a plurality of control inputs, a word line high combination of the control inputs signaling the high word line voltage should be generated and a word low combination of the control inputs signaling the low word line voltage should be generated;

receiving a word line high voltage source, a system low voltage source, and a word line low voltage source;

coupling the word line high voltage source to the word line only upon the word line high combination of control inputs being received; and

coupling the word line to both the system low voltage source and the word line low voltage source only upon the word line low combination of control inputs being received, so that the word line low voltage source does not have to sink all the voltage from the word line.

96. The method of claim 95 wherein the word line low voltage source comprises a negative voltage source.

97. The method of claim 95 wherein the system low voltage source comprises a ground voltage source.

98. The method of claim 95 wherein the word line high voltage source supplies a voltage greater than a maximum voltage of the control inputs.

99. The method of claim 95 further comprising preventing current from flowing from a higher of voltages carried by the word line low voltage source and the system low voltage source to the lower of the word line low voltage source and the system voltage.

100. A method of driving a word line by generating a high word line voltage or a low word line voltage on the word line, the method comprising:

receiving a plurality of control inputs comprising a word line high combination of the control inputs signaling the high word line voltage should be generated and a word low combination of the control inputs signaling the low word line voltage should be generated, the control inputs carrying voltages ranging between the high word line voltage and a system low voltage;

receiving a word line low voltage source;

coupling the high word line voltage to the word line only upon the word line high combination of control inputs being received; and

coupling the word line to both the system low voltage and the word line low voltage source only upon the word line low combination of control inputs being received, so that the word line low voltage source does not have to sink all the voltage from the word line.

101. The method of claim 100 wherein the word line low voltage source comprises a negative voltage source.

102. The method of claim 100 wherein the system low voltage comprises a ground voltage.