Semiconductor Device

• US 20100079203A1
• Filed: 09/24/2009
• Published: 04/01/2010
• Est. Priority Date: 09/26/2008
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Furutani, Kazuma
• Granted Patent: US 8,224,277 B2
• Time in Patent Office: Days
• US Class Current: 327/564
• 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 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: H01L 2223/6677 for antenna, e.g. antenna included within housing of semiconductor device antennas per se H01Q
• CPC Class Codes: H01L 23/645 Inductive arrangements H01L23/647, H01L23/66 take precedence
• CPC Class Codes: H01L 27/12 the substrate being other than a semiconductor body, e.g. an insulating body
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• CPC Class Codes: H01L 27/1266 the substrate on which the devices are formed not being the final device substrate, e.g. using a temporary substrate
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/12044 OLED
• CPC Class Codes: H01L 2924/3011 Impedance

Abstract

An object is to provide a semiconductor device which operates normally even when the communication distance is extremely short, while the maximum communication distance is maintained, and which can make amplitude of a response waveform large even when a large amount of electric power is supplied to the semiconductor device and a protection circuit operates. The object is achieved with a semiconductor device including a first modulation circuit and a second modulation circuit each of which performs load modulation by an input signal, a detection circuit which determines an output signal by electric power supplied externally, a protection circuit which is controlled by the output signal of the detection circuit, and a modulation selecting circuit which switches the first modulation circuit and the second modulation circuit depending on the output signal of the detection circuit.

Claims

1. A semiconductor device comprising:

an antenna for receiving electric power externally;

a first modulation circuit and a second modulation circuit each for performing load modulation;

a detection circuit for determining an output signal in accordance with a value of the electric power;

a protection circuit whose operation is controlled by a value of the output signal of the detection circuit; and

a modulation selecting circuit selecting one of the first modulation circuit and the second modulation circuit in accordance with the value of the output signal of the detection circuit.

2. The semiconductor device according to claim 1,

wherein the second modulation circuit increases amplitude of a subcarrier wave which is made to be small due to operation of the protection circuit.

3. The semiconductor device according to claim 1,

wherein a load included in the second modulation circuit is smaller than a load included in the first modulation circuit.

4. A semiconductor device comprising:

an antenna for receiving electric power externally;

a first modulation circuit and a second modulation circuit each performing load modulation;

a detection circuit for determining an output signal in accordance with a value of the electric power;

a protection circuit whose operation is controlled by a value of the output signal of the detection circuit; and

a modulation selecting circuit selecting one of the first modulation circuit and the second modulation circuit in accordance with the value of the output signal of the detection circuit,

wherein the modulation selecting circuit selects the first modulation circuit when the protection circuit does not operate, and

wherein the modulation selecting circuit selects the second modulation circuit when the protection circuit operates.

5. The semiconductor device according to claim 4,

wherein the second modulation circuit increases amplitude of a subcarrier wave which is made to be small due to operation of the protection circuit.

6. The semiconductor device according to claim 4,

wherein a load included in the second modulation circuit is smaller than a load included in the first modulation circuit.

7. A semiconductor device comprising:

an antenna to which alternating-current voltage is input externally;

a first modulation circuit and a second modulation circuit each performing load modulation;

a rectifier circuit converting the alternating-current voltage into direct-current voltage;

a detection circuit determining an output signal by a value of voltage output from the rectifier circuit;

a protection circuit suppressing output voltage of the rectifier circuit by a value of the output signal of the detection circuit; and

a modulation selecting circuit selecting one of the first modulation circuit and the second modulation circuit depending on the value of the output signal of the detection circuit,

wherein the modulation selecting circuit selects the first modulation circuit when the protection circuit does not operate, and

wherein the modulation selecting circuit selects the second modulation circuit when the protection circuit operates.

8. The semiconductor device according to claim 7,

wherein the second modulation circuit increases amplitude of a subcarrier wave which is made to be small due to operation of the protection circuit.

9. The semiconductor device according to claim 7,

wherein a load included in the second modulation circuit is smaller than a load included in the first modulation circuit.

10. A semiconductor device comprising:

an antenna for receiving electric power externally;

a first modulation circuit and a second modulation circuit each for performing load modulation;

a protection circuit for protecting the semiconductor device;

a modulation selecting circuit selecting one of the first modulation circuit and the second modulation circuit; and

a detection circuit for detecting the electric power, the detection circuit being configured to control operation of the protection circuit and operation of the modulation selecting circuit.

11. The semiconductor device according to claim 10,

wherein the second modulation circuit increases amplitude of a subcarrier wave which is made to be small due to operation of the protection circuit.

12. The semiconductor device according to claim 10,

wherein a load included in the second modulation circuit is smaller than a load included in the first modulation circuit.

13. A semiconductor device comprising:

an antenna for receiving electric power externally;

a first modulation circuit and a second modulation circuit connected to the antenna each for performing load modulation;

a detection circuit electrically connected to the antenna for detecting the electric power;

a protection circuit connected to the antenna for protecting the semiconductor device; and

a modulation selecting circuit connected to the first modulation circuit, a second modulation circuit and the detection circuit selecting one of the first modulation circuit and the second modulation circuit.

14. The semiconductor device according to claim 13,

wherein the second modulation circuit increases amplitude of a subcarrier wave which is made to be small due to operation of the protection circuit.

15. The semiconductor device according to claim 13,

wherein a load included in the second modulation circuit is smaller than a load included in the first modulation circuit.