Multi-protocol radio frequency identification transceiver

• US 7,890,080 B2
• Filed: 02/24/2010
• Issued: 02/15/2011
• Est. Priority Date: 02/22/2005
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Wu, Jiangfeng, Major, Donald Edward
• Primary Examiner(s): Urban; Edward
• Assistant Examiner(s): HU, RUI MENG
• Application Number:
  US12/711,934
• Publication Number:
  US 20100148929A1
• Time in Patent Office: 356 Days
• Field of Search: 455/336, 455/338, 455/215, 455/339, 340 101- 1052, 3405721-5729, 340/551, 340/825.59, 342/195, 342/51, 333/109, 323/220, 380/28, 341/155, 375/316, 375/346, 375/329
• US Class Current: 455/336
• 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: H04B 5/0031 for data transfer
• CPC Class Codes: H04B 5/0062 in RFID [Radio Frequency Identification] Systems
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04B 5/77 for interrogation

Abstract

A transceiver for a RFID reader and a transceiver for a RFID transponder (tag) allow communication between the two devices. The RFID reader utilizes an analog front end and a digital backend. In the receiver portion of the transceiver, the front end of the RFID reader uses a pair of down-conversion mixers to demodulate a received signal into in-phase (I) and quadrature (Q) components and analog-to-digital converters (ADC) digitize the signal. A digital signal processor (DSP) in the back end processes the digital signal and uses a matched filter for data detection. The RFID tag receives an inductively coupled signal from the reader and the receiver portion of the tag uses a pulse/level detector that employs an analog comparator and a sample and hold circuit to detect the received signal. A digital decoder/controller is used to decode the incoming data and to establish a sampling clock for the pulse/level detector. An automatic gain control (AGC) circuit adjusts a receiver gain according to the received signal strength and controls tuning of magnetic coupling circuitry.

Claims

1. An apparatus comprising:

a transmitter to transmit an outbound radio frequency (RF) signal; and

a receiver to receive a radio frequency identification (RFID) signal in response to the transmitted RF signal, demodulate the received signal in an analog front end, convert a demodulated signal from an analog form into a digital signal, and process the digital signal in a digital back end, the receiver including a digital signal processor (DSP) to process the digital signal, wherein the DSP includes a filter decimator to provide low-pass filtering on an oversampled data stream of the digital signal and decimation to a lower frequency, a band-pass filter coupled to receive an output signal of the filter decimator to eliminate noise and interference outside a bandwidth of the output signal of the filter decimator, a matched filter in combination with a programmable sequence generator that is programmable to accommodate multiple RFID communication protocols to perform a protocol-specific sequence correlation computation on an output signal of the band-pass filter, a power estimator coupled to measure estimation of the correlation computation, a data slicer to recover data and a collision detector to detect collisions when collisions occur in recovering the data, in which the data slicer and the collision detector are coupled down stream from the power estimator.

2. The apparatus of claim 1, wherein the transmitter also includes a transmitter analog front end to modulate a carrier to transmit the outbound RF signal.

3. The apparatus of claim 2, wherein the transmitter further utilizes the DSP to provide signal processing of an outbound digital signal.

4. The apparatus of claim 1, further including an attenuator at an input of the receiver to attenuate the received signal.

5. The apparatus of claim 4, wherein the attenuator is programmable to change an amount of attenuation of the received signal.

6. A radio frequency identification apparatus comprising:

an analog front end to transmit an outbound radio frequency (RF) signal, receive an inbound radio frequency identification (RFID) signal in response to the transmitted RF signal and demodulate the received signal;

an analog-to-digital converter (ADC) coupled to convert a demodulated RFID signal into a digital signal; and

a digital signal processor (DSP) to process the digital signal, wherein the DSP includes a filter decimator to provide low-pass filtering on an oversampled data stream of the digital signal and decimation to a lower frequency, a band-pass filter coupled to receive an output signal of the filter decimator to eliminate noise and interference outside a bandwidth of the output signal of the filter decimator, a matched filter in combination with a programmable sequence generator that is programmable to accommodate multiple RFID communication protocols to perform a protocol-specific sequence correlation computation on an output signal of the band-pass filter, a power estimator coupled to measure estimation of the correlation computation, a data slicer to recover data and a collision detector to detect collisions when collisions occur in recovering the data, in which the data slicer and the collision detector are coupled down stream from the power estimator.

7. The radio frequency identification apparatus of claim 6, further including an attenuator at an input of the analog front end to attenuate the inbound RFID signal.

8. The radio frequency identification apparatus of claim 7, wherein the attenuator is programmable to change an amount of attenuation in attenuating the inbound RFID signal.

9. The radio frequency identification apparatus of claim 6, wherein the analog front end uses direct conversion architecture with quadrature demodulation.

10. The radio frequency identification apparatus of claim 9, wherein the analog front end includes a pair of down-conversion mixers, a pair of band-pass filters and a pair of programmable gain amplifiers.

11. The radio frequency identification apparatus of claim 6, wherein the DSP includes a cascaded integrator-comb filter/decimator to provide low-pass filtering of the oversampled data stream from the ADC and to filter and decimate to the lower frequency.

12. The radio frequency identification apparatus of claim 11, further including a finite impulse response filter for the band-pass filter.

13. A method comprising:

transmitting an outbound radio frequency (RF) signal from a transmitter portion of a radio frequency identification device;

receiving an inbound radio frequency identification (RFID) signal in response to the transmitted RF signal in the device;

demodulating the received RFID signal by down conversion;

converting the demodulated RFID signal into a digital signal; and

processing the digital signal using a digital signal processor (DSP) by;

decimating to provide low-pass filtering on an oversampled data stream of the digital signal and decimation to a lower frequency to generate a decimated signal;

band-pass filtering the decimated signal to eliminate noise and interference outside a bandwidth of the decimated signal to generate a band-pass filtered signal;

filtering the band-pass filtered signal using a matched filter in combination with a programmable sequence generator that is programmable to accommodate multiple RFID communication protocols to perform a protocol-specific sequence correlation computation;

measuring estimation of the correlation computation using a power estimator;

recovering data using a data slicer down stream from the power estimator; and

detecting collisions using a collision detector down stream from the power estimator to detect collisions when collisions occur in recovering the data.

14. The method of claim 13, further comprising attenuating the inbound RFID signal to make the inbound signal level compatible with integrated circuit components of the device.

15. The method of claim 14, wherein the attenuating the inbound RFID signal is achieved by programmably changing an amount of attenuation in attenuating the inbound RFID signal.

16. The method of claim 13, wherein the demodulating is performed by using direct conversion architecture with quadrature demodulation.

17. The method of claim 16, wherein the demodulating includes demodulating using a pair of down-conversion mixers, a pair of band-pass filters and a pair of programmable gain amplifiers.

18. The method of claim 13, wherein the decimating includes decimating using a cascaded integrator-comb filter/decimator to provide low-pass filtering of the oversampled data stream to decimate to the lower frequency.

19. The method of claim 18, wherein the band-pass filtering includes filtering using a finite impulse response filter.