Semiconductor device and driving method thereof

• US 20050134435A1
• Filed: 12/03/2004
• Published: 06/23/2005
• Est. Priority Date: 12/19/2003
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Saito, Toshihiko, Koyama, Jun
• Granted Patent: US 7,471,188 B2
• Time in Patent Office: Days
• US Class Current: 340/10.340
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs

Abstract

There has been a problem in battryless RFID chips that a high voltage AC signal is generated when an antenna is exposed to a high electromagnetic field, and a DC voltage that is obtained through rectification of the AC signal becomes a high voltage accordingly. As a result, heat generation of a logic circuit and a clock generator circuit or element break down occur. The invention takes the following measures: a DC voltage generated through rectification of an AC signal is compared with a reference voltage in a comparator circuit, and a switch element is turned ON when the DC voltage becomes higher so as to add capacitance to an antenna circuit. Accordingly, resonance point of an antenna changes which in turn attenuates an AC signal generated in the antenna circuit, thereby suppressing a DC voltage.

Claims

1. A semiconductor device comprising:

an antenna circuit;

a converter circuit which converts an AC voltage to a DC voltage through rectification;

a comparator circuit;

a reference voltage source;

a switch element electrically connected to the comparator circuit and the ground; and

a capacitor electrically connected to the antenna circuit and the switch element,

wherein the antenna circuit is electrically connected to the converter circuit, and,

wherein the comparator circuit compares an output voltage of the reference voltage source with an output voltage of the converter circuit.

7. The semiconductor device according to claim 1, wherein the antenna circuit, the converter circuit, the comparator circuit, the capacitor and the switch element are integrally formed over the same insulating substrate.

13. The semiconductor device according to claim 1, wherein the converter circuit, the comparator circuit, the capacitor and the switch element are integrally formed over the same insulating substrate, and the antenna circuit is formed on another substrate.

19. The semiconductor device according to claim 1, wherein at lest one of the converter circuit, the comparator circuit and the switch element is formed of a thin film transistor.

25. The semiconductor device according to claim 7, wherein the insulating substrate is formed of glass, plastic or an insulating film.

31. The semiconductor device according to claim 13, wherein the insulating substrate is formed of glass, plastic or an insulating film.

37. The semiconductor device according to claim 1, wherein the antenna circuit is formed over the converter circuit, the comparator circuit or the switch element.

43. The semiconductor device according to claim 1, wherein the antenna circuit is formed over a flexible support base, wherein the antenna circuit is surrounded or sandwiched by the support base.

49. An IC card having the semiconductor device according to claim 1.

55. An RFID tag having the semiconductor device according to claim 1.

61. An RFID chip having the semiconductor device according to claim 1.

2. A semiconductor device comprising:

an antenna circuit;

a converter circuit which converts an AC voltage to a DC voltage through rectification;

a plurality of comparator circuits;

a plurality of reference voltage sources;

a plurality of switch elements each of which is electrically connected to the comparator circuit and the ground; and

,

a plurality of capacitors each of which is electrically connected to the antenna circuit and the respective switch elements,

wherein the antenna circuit is electrically connected to the converter circuit, and,

wherein the plurality of comparator circuits compare output voltages of the respective reference voltage sources with an output voltage of the converter circuit, respectively.

8. The semiconductor device according to claim 2, wherein the antenna circuit, the converter circuit, the comparator circuits, the capacitors and the switch elements are integrally formed over the same insulating substrate.

14. The semiconductor device according to claim 2, wherein the converter circuit, the comparator circuits, the capacitors and the switch elements are integrally formed over the same insulating substrate, and the antenna circuit is formed on another substrate.

20. The semiconductor device according to claim 2, wherein at lest one of the converter circuit, the comparator circuits and the switch elements is formed of a thin film transistor.

26. The semiconductor device according to claim 8, wherein the insulating substrate is formed of glass, plastic or an insulating film.

32. The semiconductor device according to claim 14, wherein the insulating substrate is formed of glass, plastic or an insulating film.

38. The semiconductor device according to claim 2, wherein the antenna circuit is formed over the converter circuit, the comparator circuits or the switch elements.

44. The semiconductor device according to claim 2, wherein the antenna circuit is formed over a flexible support base, wherein the antenna circuit is surrounded or sandwiched by the support base.

50. An IC card having the semiconductor device according to claim 2.

56. An RFID tag having the semiconductor device according to claim 2.

62. An RFID chip having the semiconductor device according to claim 2.

3. A semiconductor device comprising:

a first antenna circuit;

a second antenna circuit;

a first converter circuit which converts an AC voltage to a DC voltage through rectification;

a second converter circuit which converts an AC voltage to a DC voltage through rectification;

a comparator circuit;

a switch element electrically connected to the comparator circuit and the ground; and

a capacitor electrically connected to the first antenna circuit and the switch element,

wherein the first and the second antenna circuits are electrically connected to the first and the second converter circuits, respectively, and,

wherein a comparator circuit compares an output voltage of the first converter circuit with an output voltage of the second converter circuit.

9. The semiconductor device according to claim 3, wherein the first and the second antenna circuits, the first and the second converter circuits, the comparator circuit, the capacitor, and the switch element are integrally formed over the same insulating substrate.

15. The semiconductor device according to claim 3, wherein the first and the second converter circuits, the comparator circuit, the capacitor and the switch element are integrally formed over the same insulating substrate, and the first and the second antenna circuits are formed on another substrate.

21. The semiconductor device according to claim 3, wherein at lest one of the first and the second converter circuits, the comparator circuit and the switch element is formed of a thin film transistor.

27. The semiconductor device according to claim 9, wherein the insulating substrate is formed of glass, plastic or an insulating film.

33. The semiconductor device according to claim 15, wherein the insulating substrate is formed of glass, plastic or an insulating film.

39. The semiconductor device according to claim 3, wherein the first and the second antenna circuits are formed over the converter circuit, the comparator circuits or the switch elements.

45. The semiconductor device according to claim 3, wherein the first and the second antenna circuits are formed over a flexible support base, wherein the antenna circuit is surrounded or sandwiched by the support base.

51. An IC card having the semiconductor device according to claim 3.

57. An RFID tag having the semiconductor device according to claim 3.

63. An RFID chip having the semiconductor device according to claim 3.

4. A semiconductor device comprising:

an antenna circuit;

a converter circuit which converts an AC voltage to a DC voltage through rectification;

a comparator circuit;

a reference voltage source;

a monitor circuit electrically connected to the converter circuit and the comparator circuit;

a switch element electrically connected to the comparator circuit and the ground; and

a capacitor electrically connected to the antenna circuit and the switch element,

wherein the antenna circuit is electrically connected to the converter circuit, and

wherein the comparator circuit compares an output voltage of the reference voltage source with an output voltage of the monitor circuit.

10. The semiconductor device according to claim 4, wherein the antenna circuit, the converter circuit, the comparator circuit, the capacitor and the switch element are integrally formed over the same insulating substrate.

16. The semiconductor device according to claim 4, wherein the converter circuit, the comparator circuit, the capacitor and the switch element are integrally formed over the same insulating substrate, and the antenna circuit is formed on another substrate.

22. The semiconductor device according to claim 4, wherein at lest one of the converter circuit, the comparator circuit and the switch element is formed of a thin film transistor

28. The semiconductor device according to claim 10, wherein the insulating substrate is formed of glass, plastic or an insulating film.

34. The semiconductor device according to claim 16, wherein the insulating substrate is formed of glass, plastic or an insulating film.

40. The semiconductor device according to claim 4, wherein the antenna circuit is formed over the converter circuit, the comparator circuit or the switch element.

46. The semiconductor device according to claim 4, wherein the antenna circuit is formed over a flexible support base, wherein the antenna circuit is surrounded or sandwiched by the support base.

52. An IC card having the semiconductor device according to claim 4.

58. An RFID tag having the semiconductor device according to claim 4.

64. An RFID chip having the semiconductor device according to claim 4.

5. A semiconductor device comprising:

an antenna circuit;

a converter circuit which converts an AC voltage to a DC voltage through rectification;

a plurality of comparator circuits;

a plurality of reference voltage sources;

a monitor circuit electrically connected to the converter circuit and the comparator circuit;

a plurality of switch elements each of which is electrically connected to the comparator circuit and the ground; and

,

a plurality of capacitors each of which is electrically connected to the antenna circuit and the respective switch elements,

wherein the antenna circuit is electrically connected to the converter circuit, and

wherein the plurality of comparator circuits compare output voltages of the respective reference voltage sources with an output voltage of monitor circuit, respectively.

11. The semiconductor device according to claim 5, wherein the antenna circuit, the converter circuit, the comparator circuits, the capacitors and the switch elements are integrally formed over the same insulating substrate.

17. The semiconductor device according to claim 5, wherein the converter circuit, the comparator circuits, the capacitors and the switch elements are integrally formed over the same insulating substrate, and the antenna circuit is formed on another substrate.

23. The semiconductor device according to claim 5, wherein at lest one of the converter circuit, the comparator circuits and the switch elements is formed of a thin film transistor.

29. The semiconductor device according to claim 11, wherein the insulating substrate is formed of glass, plastic or an insulating film.

35. The semiconductor device according to claim 17, wherein the insulating substrate is formed of glass, plastic or an insulating film.

41. The semiconductor device according to claim 5, wherein the antenna circuit is formed over the converter circuit, the comparator circuits or the switch elements.

47. The semiconductor device according to claim 5, wherein the antenna circuit is formed over a flexible support base, wherein the antenna circuit is surrounded or sandwiched by the support base.

53. An IC card having the semiconductor device according to claim 5.

59. An RFID tag having the semiconductor device according to claim 5.

65. An RFID chip having the semiconductor device according to claim 5.

6. A semiconductor device comprising:

a first antenna circuit;

a second antenna circuit;

a first converter circuit which converts an AC voltage to a DC voltage through rectification;

a second converter circuit which converts an AC voltage to a DC voltage through rectification;

a comparator circuit;

a first monitor circuit electrically connected to the first converter circuit and the comparator circuit;

a second monitor circuit electrically connected to the second converter circuit and the comparator circuit;

a switch element electrically connected to the comparator circuit and the ground; and

a capacitor electrically connected to the first antenna circuit and the switch element,

wherein the first and the second antenna circuits are electrically connected to the first and the second converter circuits, respectively, and,

wherein a comparator circuit compares an output voltage of the first monitor circuit with an output voltage of the second monitor circuit.

12. The semiconductor device according to claim 6, wherein the first and the second antenna circuits, the first and the second converter circuits, the comparator circuit, the capacitor and the switch element are integrally formed over the same insulating substrate.

18. The semiconductor device according to claim 6, wherein the first and the second converter circuits, the comparator circuit, the capacitor and the switch element are integrally formed over the same insulating substrate, and the first and the second antenna circuits are formed on another substrate.

24. The semiconductor device according to claim 6, wherein at lest one of the first and the second converter circuits, the comparator circuit and the switch element is formed of a thin film transistor.

30. The semiconductor device according to claim 12, wherein the insulating substrate is formed of glass, plastic or an insulating film.

36. The semiconductor device according to claim 18, wherein the insulating substrate is formed of glass, plastic or an insulating film.

42. The semiconductor device according to claim 6, wherein the first and the second antenna circuits are formed over the converter circuit, the comparator circuits or the switch elements.

48. The semiconductor device according to claim 6, wherein the first and the second antenna circuits are formed over a flexible support base, wherein the antenna circuit is surrounded or sandwiched by the support base.

54. An IC card having the semiconductor device according to claim 6.

60. An RFID tag having the semiconductor device according to claim 6.

66. An RFID chip having the semiconductor device according to claim 6.

67. A driving method of a semiconductor device, comprising the steps of:

converting an AC voltage generated in an antenna circuit to a DC voltage through rectification;

comparing the DC voltage with a reference voltage;

connecting a capacitor in parallel to the antenna circuit when the DC voltage reaches higher than the reference voltage;

attenuating the AC voltage generated in the antenna circuit; and

converting the attenuated AC voltage to a DC voltage through rectification.

68. A driving method of a semiconductor device, comprising the steps of:

converting an AC voltage generated in an antenna circuit to a DC voltage through rectification;

comparing the DC voltage with a plurality of reference voltages;

connecting a capacitor being corresponding to the reference voltage at higher level than the DC voltage in parallel to the antenna circuit when the DC voltage reaches higher than any one of the reference voltages;

attenuating the AC voltage generated in the antenna circuit; and

converting the attenuated AC voltage to a DC voltage through rectification.

69. A driving method of a semiconductor device, comprising the steps of:

converting an AC voltage generated in a first antenna circuit to a first DC voltage through rectification;

converting an AC voltage generated in a second antenna circuit to a second DC voltage through rectification;

comparing the first DC voltage with a the second DC voltage;

connecting a capacitor in parallel to the antenna circuit when the first DC voltage reaches higher than the second DC voltage;

attenuating the AC voltage generated in the first antenna circuit; and

converting the attenuated AC voltage to a DC voltage through rectification.