Semiconductor device and wireless communication system

• US 20070036237A1
• Filed: 08/04/2006
• Published: 02/15/2007
• Est. Priority Date: 08/11/2005
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kobayashi, Hidetomo, Atsumi, Tomoaki
• Granted Patent: US 7,826,552 B2
• Time in Patent Office: Days
• US Class Current: 375/269
• 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: H04B 5/77 for interrogation
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04L 27/04 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/12 Modulator circuits; Transmitter circuits

Abstract

The present invention provides a structure in which an amplitude-modulation mode and a frequency-modulation mode are switched. A semiconductor device of the invention has: a reset control circuit to which a modulation mode select signal which selects an amplitude-modulation mode or a frequency-modulation mode and Manchester-encoded information are input, which outputs a first reset signal and a second reset signal; a first frequency-dividing circuit to which a carrier wave is input, which outputs a sub-carrier wave responding to the amplitude-modulation mode or a frequency-modulation signal responding to the frequency-modulation mode, according to the first reset signal; a second frequency-dividing circuit which outputs a basic clock of which a duty ratio is different between the amplitude-modulation mode and the frequency-modulation mode, according to the second reset signal and an output of the first frequency-dividing circuit; and an ASK/FSK switching portion to which an output from the first frequency-dividing circuit and Manchester-encoded information are input, which outputs an amplitude-modulation signal or a frequency-modulation signal according to the modulation mode select signal.

Claims

1. A semiconductor device which inputs and outputs data by wireless communication, comprising:

a reset control circuit to which a modulation mode select signal that selects an amplitude-modulation mode or a frequency-modulation mode, and Manchester-encoded information are input, which outputs a first reset signal and a second reset signal;

a first frequency-dividing circuit to which a carrier wave is input, which outputs a sub-carrier wave responding to an amplitude-modulation mode or a frequency-modulation signal responding to a frequency-modulation mode, according to the first reset signal;

a second frequency-dividing circuit which outputs a basic clock signal of which a duty ratio is different between an amplitude-modulation mode and a frequency-modulation mode, according to the second reset signal and an output of the first frequency-dividing circuit; and

an ASK/FSK switching portion to which an output from the first frequency-dividing circuit and the Manchester-encoded information are input, which outputs an amplitude-modulation signal or the frequency-modulation signal, according to the modulation mode select signal.

3. The semiconductor device according to claim 1 or 2, wherein the ASK/FSK switching portion comprises:

an ASK signal generating portion to which the Manchester-encoded information and a sub-carrier wave responding to the amplitude-modulation mode or the frequency-modulation signal responding to a frequency-modulation mode output from the first frequency-dividing circuit are input, which outputs an amplitude-modulation signal by arithmetically processing the sub-carrier wave responding to the amplitude-modulation mode and the Manchester-encoded information, and outputs the frequency-modulation signal; and

an output signal switching portion to which an output from the ASK signal generating portion is input, which outputs the amplitude-modulation signal or the frequency-modulation signal, by switching the two, according to the modulation mode select signal.

4. The semiconductor device according to claim 1 or 2, wherein a control signal from the first frequency-dividing circuit and a count signal from the second frequency-dividing circuit are input to the reset control circuit.

5. The semiconductor device according to claim 1 or 2, further comprising:

an encoding circuit to which each data of flag, DSFID, UID, and CRC is input sequentially, which Manchester-encodes them and outputs them sequentially; and

an SOF-EOF adding circuit to which an output of the encoding circuit is input, which generates the Manchester-encoded information by adding SOF and EOF to the output of the encoding circuit, and outputs the Manchester-encoded information.

6. The semiconductor device according to claim 1 or 2, further comprising a modulating circuit to which the amplitude-modulation signal or the frequency-modulation signal is input from the ASK/FSK switching portion, which load-modulates the carrier wave by the amplitude-modulation signal or the frequency-modulation signal.

7. The semiconductor device according to claim 1 or 2, further comprising:

a modulating circuit to which the amplitude-modulation signal or the frequency-modulation signal is input from the ASK/FSK switching portion, which load-modulates the carrier wave by the amplitude-modulation signal or the frequency-modulation signal; and

an antenna which transmits the load-modulated carrier wave.

8. A wireless communication system comprising the semiconductor device according to claim 1 or 2, and a reader/writer which inputs and outputs data from/to the semiconductor device by wireless communication.

2. A semiconductor device which inputs and outputs data by wireless communication, comprising:

a reset control circuit to which a modulation mode select signal that selects an amplitude-modulation mode or a frequency-modulation mode, and Manchester-encoded information are input, which outputs a first reset signal and a second reset signal;

a first frequency-dividing circuit to which a carrier wave is input, which outputs a sub-carrier wave responding to an amplitude-modulation mode or a frequency-modulation signal responding to a frequency-modulation mode, according to the first reset signal;

a low-speed/high-speed switching portion to which an output of the first frequency-dividing circuit is input, which outputs a basic clock control signal according to a selected data transmission rate;

a second frequency-dividing circuit which outputs a basic clock signal of which a duty ratio is different between an amplitude-modulation mode and a frequency-modulation mode, and of which a cycle is different according to a data transmission rate, according to the second reset signal and the basic clock control signal; and

an ASK/FSK switching portion to which an output from the first frequency-dividing circuit and the Manchester-encoded information are input, which outputs an amplitude-modulation signal or the frequency-modulation signal, according to the modulation mode select signal.