RFID TRANSPONDER WITH IMPROVED WAKE PATTERN DETECTION AND METHOD

• US 20100141389A1
• Filed: 12/02/2009
• Published: 06/10/2010
• Est. Priority Date: 12/02/2008
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments Deutschland Gesellschaft Mit Beschrã¤Nkter Haftung (Texas Instruments, Inc.)
• Inventors: Muellner, Ernst, Hagl, Andreas
• Granted Patent: US 8,629,763 B2
• Time in Patent Office: Days
• US Class Current: 340/10.100
• CPC Class Codes: G06K 19/0707 the arrangement being capable of collecting energy from external energy sources, e.g. thermocouples, vibration, electromagnetic radiation G06K19/0702 takes precedence
• CPC Class Codes: G06K 19/0712 the arrangement being capable of triggering distinct operating modes or functions dependent on the strength of an energy or interrogation field in the proximity of the record carrier active means for hindering electromagnetic reading or writing G06K19/07336
• 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: H04W 52/028 switching on or off only a part of the equipment circuit blocks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

An RFID transponder is provided which includes an automatic gain control (AGC) stage for amplifying a radio frequency (RF) signal and for providing an amplified RF signal. The AGC stage has a control signal indicating an increase of the amplitude of the RF signal. A demodulator is coupled to receive the amplified RF signal for demodulating the amplified RF signal. The demodulator provides a data signal. A burst detector is coupled to receive the control signal of the AGC stage and adapted to provide a start signal in response to a change of the control signal. A wake pattern detector is coupled to receive the data signal and the start signal. The wake pattern detector is adapted to detect a predefined wake pattern in the data signal after having received the start signal and to issue a wake signal if the predefined wake pattern is detected for switching the RFID transponder from a first operating mode into a second operating mode having higher power consumption than the first operating mode.

Claims

1. An RFID transponder comprising:

an automatic gain control (AGC) stage for amplifying a radio frequency (RF) signal and for providing an amplified RF signal, the AGC stage having a control signal indicating an increase of the amplitude of the RF signal;

a demodulator coupled to receive the amplified RF signal for demodulating the amplified RF signal and for providing a data signal;

a burst detector coupled to receive the control signal of the AGC stage and adapted to provide a start signal in response to a change of the control signal; and

a wake pattern detector coupled to receive the data signal and the start signal, wherein the wake pattern detector is adapted to detect a predefined wake pattern in the data signal after having received the start signal and to issue a wake signal if the predefined wake pattern is detected for switching the RFID transponder from a first operating mode into a second operating mode having higher power consumption than the first operating mode.

2. The RFID transponder according to claim 1, wherein the data signal is a binary signal and the wake pattern has a bit length of less than sixteen bits.

3. The RFID transponder according to claim 1, wherein the wake pattern detector is returned to a power-down mode after a period of time that is longer than a duration that relates to a valid single bit.

4. The RFID transponder according to claim 1, wherein the wake pattern detector is returned to a power-down mode after a period of time that spans a single predefined wake pattern.

5. The RFID transponder according to claim 1, wherein the bit length is four.

6. The RFID transponder according to claim 2, wherein the wake pattern detector is returned to a power-down mode after a period of time that is longer than a duration that relates to a valid single bit.

7. The RFID transponder according to claim 2, wherein the wake pattern detector is returned to a power-down mode after a period of time that spans a single predefined wake pattern.

8. The RFID transponder according to claim 3, wherein the wake pattern detector is returned to a power-down mode after a period of time that spans a single predefined wake pattern.

10. The method of claim 5, further comprising returning the wake pattern detector into power-down mode when a period of time has expired after receipt of the start signal which covers a single wake pattern or which is longer than a duration relating to a valid single bit.

9. Method of operating an RFID transponder, the method comprising:

providing a start signal in response to an increase of the amplitude of a radio frequency (RF) signal received with an antenna of the RFID transponder;

demodulating the RF signal into a data signal;

monitoring the data signal for a predefined wake pattern after the start signal occurred; and

switching the RFID transponder from a power-down mode into an active mode if the wake pattern is detected.