Semiconductor integrated circuit and wireless communication device

• US 7,822,383 B2
• Filed: 08/23/2005
• Issued: 10/26/2010
• Est. Priority Date: 09/02/2004
• Status: Active Grant

• Current Assignee: FeliCa Networks, Inc (Sony Group Corp.)
• Original Assignee: FeliCa Networks, Inc (Sony Group Corp.)
• Inventors: Miyagawa, Yoichi, Suzuki, Mamoru, Yoshida, Yuko, Enomoto, Kazuyoshi
• Primary Examiner(s): NGUYEN, SIMON
• Application Number:
  US10/577,727
• Publication Number:
  US 20080280648A1
• Time in Patent Office: 1,890 Days
• Field of Search: 455 411- 413, 455/558, 455/333, 340/10.1, 340/10.34, 340 1042- 1052, 340/572.1
• US Class Current: 455/39
• 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 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10237 the reader and the record carrier being capable of selectively switching between reader and record carrier appearance, e.g. in near field communication [NFC] devices where the NFC device may function as an RFID reader or as an RFID tag

Abstract

The present invention relates to a semiconductor integrated circuit and a wireless communication apparatus that can be reduced in size without deteriorating a receiving sensitivity and a transmission efficiency. Communication with an external reader/writer and an external non-contact IC card is carried out through a common antenna 211. The signal received from the external reader/writer or the external non-contact IC card through the antenna is supplied to an ASK demodulation circuit 149 and demodulated. The signal received from the external reader/writer is full-wave rectified and smoothed by an full-wave rectification and smoothing circuit composed of diodes 231, 232 and a capacitor 233, and the power obtained from the full-wave rectified and smoothed signal is supplied to respective units of a semiconductor integrated circuit 101. The present invention can be applied to a mobile phone.

Claims

1. A wireless communication apparatus with a semiconductor integrated circuit which has a non-contact IC card function and a wireless reader/writer function for a non-contact IC card, comprising:

an antenna configured to carry out communication with an external non-contact IC card and an external wireless reader/writer, said antenna including a loop of coil with plural windings;

demodulation means for demodulating a first received signal transmitted from the external wireless reader/writer and received through the antenna or a second received signal transmitted from the external non-contact IC card;

full-wave rectification and smoothing means for subjecting the first received signal to full-wave rectification and smoothing;

first transmission means for transmitting a first transmission signal to the external wireless reader/writer through the antenna while the semiconductor integrated circuit is in an non-contact IC card mode of operation;

second transmission means for transmitting a second transmission signal to the external non-contact IC card through the antenna while the semiconductor integrated circuit is in a wireless reader/writer mode of operation; and

a capacitor connecting the second transmission means to a center tap of the antenna, wherein when the second transmission means drives the antenna, a current from the second transmission means flows only to a half of the windings of the loop of coil of the antenna and an another current flows through a remaining portion of the loop of coil by electromagnetic induction.

2. A wireless communication apparatus according to claim 1, further comprising stabilization means for stabilizing the power obtained from the first received signal subjected to the full-wave rectification and smoothing by the full-wave rectification and smoothing means.

3. A wireless communication apparatus according to claim 1, wherein the first transmission means is connected behind the full-wave rectification and smoothing means as well as transmits the first transmission signal by changing a load of an antenna of the external wireless reader/writer electromagnetically coupled with the antenna.

4. A wireless communication apparatus according to claim 1, wherein the second transmission means transmits the second transmission signal that is a differential signal created based on a transmission carrier signal having a predetermined frequency and data to be transmitted to the external non-contact IC card.

5. A wireless communication apparatus according to claim 1, wherein the demodulation means demodulates the first received signal as a differential signal or the second received signal as the differential signal.

6. A wireless communication apparatus of claim 1, further comprising:

a battery;

a power supply control unit configured to supply power to components of the wireless communication apparatus received from the external wireless reader/writer while the wireless communication apparatus is in the non-contact IC card mode of operation, and to supply power to components of the wireless communication apparatus from the battery while the wireless communication apparatus is in the wireless reader/writer mode of operation.

7. A wireless communication apparatus of claim 6, wherein the power supply control unit is further configured to provide power to components of the wireless communication apparatus from both the battery and from the external wireless reader/writer while the wireless communication apparatus is in the non-contact IC card mode of operation.

8. A wireless communication apparatus which has a non-contact IC card function and a wireless reader/writer function for non-contact IC card comprising:

an antenna configured to carry out communication with an external non-contact IC card and an external wireless reader/writer;

a demodulation unit configured to demodulate for demodulating a first received signal transmitted from the external wireless reader/writer and received through the antenna or a second received signal transmitted from the external non-contact IC card and received through the antenna;

a full-wave rectification and smoothing unit configured to subject the first received signal to full-wave rectification and smoothing;

a first transmission unit configured to transmit a first transmission signal to the external wireless reader/writer through the antenna while the wireless communication apparatus is in an non-contact IC card mode of operation;

a second transmission unit configured to transmit a second transmission signal to the external non-contact IC card through the antenna while the wireless communication apparatus is in an wireless reader/writer mode of operation; and

a capacitor connecting the second transmission unit a center tap of the antenna, wherein when the second transmission unit drives the antenna, a current from the second transmission unit flows only to a half of the windings of the loop of coil of the antenna and an another current flows through a remaining portion of the loop of coil by electromagnetic induction.

9. A wireless communication apparatus of claim 8, further comprising:

a battery;

a power supply control unit configured to supply power to components of the wireless communication apparatus received from the external wireless reader/writer while the wireless communication apparatus is in the non-contact IC card mode of operation, and to supply power to components of the wireless communication apparatus from the battery while the wireless communication apparatus is in the wireless reader/writer mode of operation.

10. A wireless communication apparatus of claim 9, wherein the power supply control unit is further configured to provide power to components of the wireless communication apparatus from both the battery and from the external wireless reader/writer while the wireless communication apparatus is in the non-contact IC card mode of operation.