Semiconductor device and wireless communication system using the same

• US 8,018,341 B2
• Filed: 05/17/2006
• Issued: 09/13/2011
• Est. Priority Date: 05/19/2005
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kobayashi, Hidetomo, Atsumi, Tomoaki, Shionoiri, Yutaka
• Primary Examiner(s): Nguyen; Hung T.
• Application Number:
  US11/919,497
• Publication Number:
  US 20090079572A1
• Time in Patent Office: 1,945 Days
• Field of Search: 340/572.1, 340/572.4, 340/572.7, 340/825.69, 340/825.72, 340/572.8, 340/634, 340/653, 235/487, 235/492, 235/375, 235/376, 235/380, 235/383
• US Class Current: 340/572.1
• CPC Class Codes: G06K 19/0708 the source being electromagnetic or magnetic
• 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

Abstract

Initialization of a semiconductor device can be efficiently performed, which transmits and receives data through wireless communication. The semiconductor device includes an antenna, a power source circuit, a circuit which uses a DC voltage generated by the power source circuit as a power source voltage, and a resistor. The antenna includes a pair of terminals and receives a wireless signal (a modulated carrier wave). The power source circuit includes a first terminal and a second terminal and generates a DC voltage between the first terminal and the second terminal by using a received wireless signal (the modulated carrier wave). The resistor is connected between the first terminal and the second terminal. In this manner, the semiconductor device and the wireless communication system can transmit and receive data accurately.

Claims

1. A semiconductor device comprising:

an antenna transmitting and receiving a modulated carrier wave;

a band-pass filter connected to the antenna;

a power source circuit including a first terminal and a second terminal and generating a DC voltage between the first terminal and the second terminal by the modulated carrier wave inputted through the band-pass filter;

a circuit using the DC voltage as a power source voltage; and

a resistor connected to the first terminal and the second terminal,

wherein the power source circuit comprises a rectifying circuit which rectifies the inputted modulated carrier wave through the band-pass filter and converts the inputted modulated carrier wave to a DC signal and a holding capacitor which smoothes the DC signal outputted from the rectifying circuit, and

wherein the power source circuit outputs the DC signal smoothed by the holding capacitor as the DC voltage.

2. The semiconductor device according to claim 1, wherein the same potential is applied to a terminal of the antenna and the first terminal.

3. The semiconductor device according to claim 1, wherein a terminal of the antenna and the first terminal are grounded.

4. The semiconductor device according to claim 1, wherein the circuit using the DC voltage as the power source voltage comprises a demodulation circuit which demodulates the modulated carrier wave, an analyzing circuit which analyzes data demodulated by the demodulation circuit, and a memory which operates based on the data analyzed by the analyzing circuit.

5. The semiconductor device according to claim 4, wherein the circuit using the DC voltage as the power source voltage further comprises an encoding circuit which encodes the data read from the memory, and a modulation circuit which modulates a carrier wave in accordance with the data encoded by the encoding circuit.

6. The semiconductor device according to claim 4, wherein the memory is any one of a DRAM, an SRAM, a FeRAM, a mask ROM, an EPROM, an EEPROM, and a flash memory.

7. The semiconductor device according to claim 1, wherein the resistor has electric resistance of 500 kΩ

to 2 MΩ

.

8. The semiconductor device according to claim 1, wherein the resistor is formed by a semiconductor layer.

9. The semiconductor device according to claim 1, wherein the circuit using the DC voltage as the power source voltage comprises a thin film transistor, and

wherein the resistor is formed by a semiconductor layer formed simultaneously with a semiconductor layer which functions as an active layer of the thin film transistor.

10. The semiconductor device according to claim 9, wherein an impurity element which imparts conductivity is added to the semiconductor layer of the resistor.

11. The semiconductor device according to claim 9, wherein an impurity element which imparts conductivity is added to the semiconductor layer of the resistor at approximately the same concentration as a channel forming region of the thin film transistor.

12. The semiconductor device according to claim 1, wherein the antenna is any one of a dipole antenna, a patch antenna, a loop antenna, and a Yagi antenna.

13. The semiconductor device according to claim 1, wherein the modulated carrier wave is formed by modulating a carrier wave in an analog modulation method or a digital modulation method.

14. The semiconductor device according to claim 1, wherein the antenna transmits and receives the modulated carrier wave by any one of an electromagnetic coupling method, an electromagnetic induction method, and a radio wave method.