Semiconductor device

• US 20080191951A1
• Filed: 02/06/2008
• Published: 08/14/2008
• Est. Priority Date: 02/09/2007
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kato, Taichi
• Granted Patent: US 7,940,224 B2
• Time in Patent Office: Days
• US Class Current: 343/722
• 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
• CPC Class Codes: G06K 19/0726 the arrangement including a circuit for tuning the resonance frequency of an antenna on the record carrier

Abstract

It is an object of the present invention to provide a semiconductor device which can be surely supplied electric power by electromagnetic waves in different frequency bands without preventing reduction in size and weight of a semiconductor device. A semiconductor device capable of wireless communication is provided with a frequency determining circuit which detects the frequency of the electromagnetic waves received by the antenna and a circuit which automatically adjusts impedance in accordance with information from the frequency determining circuit, and the semiconductor device communicates and obtains electric power by one antenna. For adjustment of impedance, a circuit which can change the inductance or the capacitance, or an antenna which can change the length is used.

Claims

1. A semiconductor device capable of wireless communication comprising:

an inductance generation circuit including a first switch, a second switch and a coil;

a frequency determining circuit; and

an antenna,

wherein an input portion of the inductance generation circuit is electrically connected to the first switch and the second switch,

wherein the first switch is electrically connected to an output portion of the inductance generation circuit,

wherein the second switch is electrically connected to the coil of the inductance generation circuit,

wherein an input portion of the frequency determining circuit is electrically connected to the antenna, and

wherein the frequency determining circuit is configured to control the first switch and the second switch in accordance with a frequency of electromagnetic waves received by the antenna.

2. The semiconductor device capable of wireless communication according to claim 1, further comprising a demodulation circuit including a first capacitor element, a second capacitor element, a third switch and a fourth switch,

wherein an input portion of the demodulation circuit is electrically connected to the third switch and the fourth switch,

wherein the third switch is electrically connected to the first capacitor element,

wherein the fourth switch is electrically connected to the second capacitor element,

wherein the frequency determining circuit is configured to control the third switch and the fourth switch in accordance with the frequency of electromagnetic waves received by the antenna, and

wherein a capacitance of the first capacitor element and a capacitance of the second capacitor element are different in level.

3. The semiconductor device capable of wireless communication according to claim 1, further comprising a rectifier circuit including a third capacitor element, a fourth capacitor element, a fifth switch and a sixth switch,

wherein an input portion of the rectifier circuit is electrically connected to the fifth switch and the sixth switch,

wherein the fifth switch is electrically connected to the third capacitor element;

wherein the sixth switch is electrically connected to the fourth capacitor element,

wherein the frequency determining circuit is configured to control the fifth switch and the sixth switch in accordance with the frequency of electromagnetic waves received by the antenna, and

wherein a capacitance of the third capacitor element and a capacitance of the fourth capacitor element are different in level.

4. The semiconductor device capable of wireless communication according to claim 1, further comprising:

a demodulation circuit including a first capacitor element, a second capacitor element, a third switch and a fourth switch;

a rectifier circuit including a third capacitor element, a fourth capacitor element, a fifth switch and a sixth switch,

wherein an input portion of the demodulation circuit is electrically connected to the third switch and the fourth switch,

wherein the third switch is electrically connected to the first capacitor element,

wherein the fourth switch is electrically connected to the second capacitor element,

wherein the frequency determining circuit is configured to control the third switch and the fourth switch in accordance with the frequency of electromagnetic waves received by the antenna, and

wherein a capacitance of the first capacitor element and a capacitance of the second capacitor element are different in level,

wherein an input portion of the rectifier circuit is electrically connected to the third switch and the fourth switch,

wherein the fifth switch is electrically connected to the third capacitor element,

wherein the sixth switch is electrically connected to the fourth capacitor element,

wherein the frequency determining circuit is configured to control the fifth switch and the sixth switch in accordance with the frequency of electromagnetic waves received by the antenna, and

wherein a capacitance of the third capacitor element and a capacitance of the fourth capacitor element are different in level.

5. The semiconductor device capable of wireless communication according to claim 1,

wherein each of the first switch and the second switch is a transistor.

6. The semiconductor device capable of wireless communication according to claim 2,

wherein each of the third switch and the fourth switch is a transistor.

7. The semiconductor device capable of wireless communication according to claim 3,

wherein each of the fifth switch and the sixth switch is a transistor.

8. The semiconductor device capable of wireless communication according to claim 1,

wherein the semiconductor device has a wirelessly chargeable battery.

9. A semiconductor device capable of wireless communication comprising:

a demodulation circuit including a first capacitor element, a second capacitor element, a first switch and a second switch;

a frequency determining circuit; and

an antenna,

wherein an input portion of the demodulation circuit is electrically connected to the first switch and the second switch,

wherein the first switch is electrically connected to the first capacitor element,

wherein the second switch is electrically connected to the second capacitor element,

wherein an input portion of the frequency determining circuit is electrically connected to the antenna,

wherein the frequency determining circuit is configured to control the first switch and the second switch in accordance with the frequency of electromagnetic waves received by the antenna, and

wherein capacitance of the first capacitor element and capacitance of the second capacitor element are different in level.

10. The semiconductor device capable of wireless communication according to claim 9,

wherein each of the first switch and a second switch is a transistor.

11. The semiconductor device capable of wireless communication according to claim 9,

wherein the semiconductor device has a wirelessly chargeable battery.

12. A semiconductor device capable of wireless communication comprising:

a rectifier circuit including a first capacitor element, a second capacitor element, a first switch and a second switch;

a frequency determining circuit; and

an antenna,

wherein an input portion of the rectifier circuit is electrically connected to the first switch and the second switch,

wherein the first switch is electrically connected to the first capacitor element,

wherein the second switch is electrically connected to the second capacitor element,

wherein an input circuit of the frequency determining circuit is electrically connected to the antenna,

wherein the frequency determining circuit is configured to control the first switch and the second switch in accordance with the frequency of electromagnetic waves received by the antenna, and

wherein a capacitance of the first capacitor element and a capacitance of the second capacitor element are different in level.

13. The semiconductor device capable of wireless communication according to claim 12,

wherein each of the first switch and the second switch is a transistor.

14. The semiconductor device capable of wireless communication according to claim 12,

wherein the semiconductor device has a wirelessly chargeable battery.

15. A semiconductor device capable of wireless communication comprising:

a rectifier circuit including a first capacitor element and a second capacitor element;

a demodulation circuit including a third capacitor element and a fourth capacitor element;

a frequency determining circuit; and

an antenna,

wherein an input portion of the rectifier circuit is electrically connected to a first switch and a second switch,

wherein the first switch is electrically connected to the first capacitor element,

wherein the second switch is electrically connected to the second capacitor element,

wherein an input portion of the demodulation circuit is electrically connected to a third switch and a fourth switch,

wherein the third switch is electrically connected to the third capacitor element,

wherein the fourth switch is electrically connected to the fourth capacitor element,

wherein an input portion of the frequency determining circuit is electrically connected to the antenna,

wherein the circuit determining frequency is configured to control the first to fourth switches in accordance with the frequency of electromagnetic waves received by the antenna,

wherein a capacitance of the first capacitor element and a capacitance of the second capacitor element are different in level, and

wherein a capacitance of the third capacitor element and a capacitance of the fourth capacitor element are different in level.

16. The semiconductor device capable of wireless communication according to claim 15,

wherein each of the first to fourth switches is a transistor.

17. The semiconductor device capable of wireless communication according to claim 15,

wherein the semiconductor device has a wirelessly chargeable battery.

18. A semiconductor device capable of wireless communication comprising:

an antenna; and

a frequency determining circuit,

wherein the antenna includes a main portion and an end portion,

wherein the main portion and the end portion are electrically connected to a first switch,

wherein the input portion of the circuit determining frequency is electrically connected to the antenna, and

wherein the frequency determining circuit is configured to control the first switch in accordance with a frequency of electromagnetic waves received by the antenna.

19. The semiconductor device capable of wireless communication according to claim 18,

wherein the first switch is a transistor.

20. The semiconductor device capable of wireless communication according to claim 18,

wherein the semiconductor device has a wirelessly chargeable battery.

21. The semiconductor device capable of wireless communication according to claim 18, further comprising a demodulation circuit including a first capacitor element, a second capacitor element, a second switch and a third switch,

wherein an input portion of the demodulation circuit is electrically connected to the second switch and the third switch,

wherein the second switch is electrically connected to the first capacitor element,

wherein the third switch is electrically connected to the second capacitor element,

wherein the frequency determining circuit is configured to control the second switch and the third switch in accordance with the frequency of electromagnetic waves received by the antenna, and

wherein a capacitance of the first capacitor element and a capacitance of the second capacitor element are different in level.

22. The semiconductor device capable of wireless communication according to claim 18, further comprising a rectifier circuit including a third capacitor element, a fourth capacitor element, a fourth switch and a fifth switch,

wherein an input portion of the rectifier circuit is electrically connected to the fourth switch and the fifth switch,

wherein the fourth switch is electrically connected to the third capacitor element,

wherein the fifth switch is electrically connected to the fourth capacitor element,

wherein the frequency determining circuit is configured to control the fourth switch and the fifth switch in accordance with the frequency of electromagnetic waves received by the antenna, and

wherein a capacitance of the third capacitor element and a capacitance of the fourth capacitor element are different in level.

23. The semiconductor device capable of wireless communication according to claim 18, further comprising an inductance generation circuit including a sixth switch, a seventh switch and a coil,

wherein an input portion of the inductance generation circuit is electrically connected to the sixth switch and the seventh switch,

wherein the sixth switch is electrically connected to an output portion of the inductance generation circuit,

wherein the seventh switch is electrically connected to the coil of the inductance generation circuit,

wherein an input portion of the frequency determining circuit is electrically connected to the antenna, and

wherein the frequency determining circuit is configured to control the sixth switch and the seventh switch in accordance with the frequency of electromagnetic waves received by the antenna.