Multi-mode rfid reader architecture

Abstract

A multi-mode RFID reader operates in both far field mode and near field mode. The multi-mode RFID reader includes a transmitter section, a receiver section, a transmit multiplexer and a receive multiplexer. Both the transmit multiplexer and the receive multiplexer are configurably coupled to a far field antenna structure and a near field coil structure. For far field operation, the transmit multiplexer provides an up-converted outbound signal to a far field antenna structure and the receive multiplexer provides an inbound signal to a receiver section. For near field operation, the transmit multiplexer provides an up-converted outbound signal to the near field coil structure and the receive multiplexer provides an inbound signal to the receiver section.

1 . A multi-mode radio frequency identification (RFID) reader comprises:
 a baseband processing module coupled to:
 convert outbound data into outbound modulation information; and 
 convert an encoded inbound signal into inbound data; 
   a transmitter section coupled to convert the outbound modulation information into an up-converted outbound signal;   a far field antenna structure;   a near field coil structure;   a transmit multiplexer coupled to output the up-converted outbound signal to the near field coil structure when the multi-mode RFID reader is in a near field mode and to output the up-converted outbound signal to the far field antenna structure when the multi-mode RFID reader is in a far field mode;   a receive multiplexer coupled to input an inbound signal from the near field coil structure when the multi-mode RFID reader is in the near field mode and to input the inbound signal from the far field antenna structure when the multi-mode RFID reader is in the far field mode; and   a receiver section coupled to down-convert the inbound signal into the encoded inbound signal.   
   
   
       2 . The multi-mode RFID reader of  claim 1 , wherein the far field antenna structure comprises:
 an antenna;   a transformer balun coupled to the antenna.   
   
   
       3 . The multi-mode RFID reader of  claim 1 , wherein the near field coil structure comprises:
 a plurality of coils;   a plurality of capacitors coupled to the plurality of coils.   
   
   
       4 . The multi-mode RFID reader of  claim 1 , wherein the transmitter section comprises:
 a current source modulated based on the outbound modulation information; and   input transistors coupled to the current source.   
   
   
       5 . The multi-mode RFID reader of  claim 4 , wherein the transmit multiplexer comprises:
 multiplexer transistors operable to couple the input transistors to the near field coil structure when in the near field mode and to the far field antenna structure when in the far field mode.   
   
   
       6 . The multi-mode RFID reader of  claim 5 , wherein the multiplexer transistors comprise:
 a first set of transistors coupled to the input transistors and the near field coil structure, wherein each of the first set of transistors includes an activation input; and   a second set of transistors coupled to the input transistors and the far field antenna structure, wherein each of the second set of transistors includes an activation input.   
   
   
       7 . The multi-mode RFID reader of  claim 6 , wherein the transmitter section is operable to signal the transmit multiplexer to activate the first set of transistors to transmit in the near field mode and to signal the transmit multiplexer to activate the second set of transistors to transmit in the far field mode. 
   
   
       8 . The multi-mode RFID reader of  claim 4 , wherein the transmitter section comprises:
 a transmitter driver circuit, including:
 a power amplifier with outputs coupled to inputs of the input transistors; 
 a plurality of capacitors configurably coupled to the outputs of the power amplifier and to the inputs of the input transistors; and 
 a plurality of inductors coupled to the outputs of the power amplifier and to the inputs of the input transistors. 
   
   
   
       9 . The multi-mode RFID reader of  claim 1 , wherein the baseband processing module further functions to:
 encode the outbound data using a first encoding protocol when in the near field mode and using a second encoding protocol when in the far field mode.   
   
   
       10 . The multi-mode RFID reader of  claim 1 , wherein the up-converted outbound signal and the inbound signal are in the ultra high frequency (UHF) range. 
   
   
       11 . The multi-mode RFID reader of  claim 1 , wherein the baseband processing module further functions to transmit one or more control signals to the transmitter section, wherein the transmitter section operates in the far field mode or the near field mode in response to the one or more control signals. 
   
   
       12 . The multi-mode RFID reader of  claim 11 , wherein the transmitter section further functions to:
 signal the transmit multiplexer to couple the up-converted outbound signal to the near field coil structure when the one or more control signals indicates the near field mode; and   signal the transmit multiplexer to couple the up-converted outbound signal to the far field antenna structure when the one or more control signals indicates the far field mode.   
   
   
       13 . The multi-mode RFID reader of  claim 11 , wherein the baseband processing module further functions to transmit a signal to the transmitter section, wherein the signal indicates whether the transmitter section is to transmit in the far field mode or the near field mode. 
   
   
       14 . The multi-mode RFID reader of  claim 11 , wherein the baseband processing module is operable to:
 in response to a receive signal strength indication from one or more tags, encoding a data signal command for transmission by the transmitter section in the far field mode to the one or more tags to operate in the near field mode; and   upon receipt of a decoded data signal from the one or more tags with an acknowledgement of the command, transmitting the one or more control signals to the transmitter section to transmit in the near field mode to the one or more tags.   
   
   
       15 . The multi-mode RFID reader of  claim 11 , wherein the baseband processing module is operable to:
 in response to a receive signal strength indication from one or more tags or an inbound encoded signal that the baseband processing module is unable to decode, encode a data signal command for transmission by the transmitter section in the near field mode to the one or more tags to operate in the far field mode; and   upon receipt of a decoded data signal from the one or more tags with an acknowledgement of the command, transmitting the one or more control signals to the transmitter section to transmit in the far field mode to the one or more tags.   
   
   
       16 . The multi-mode RFID reader of  claim 11 , wherein the multi-mode RFID reader operates in the far field mode as a default mode. 
   
   
       17 . An radio frequency identification (RFID) reader, comprising:
 a baseband processing module operable to:
 convert outbound data into outbound encoded data; and 
 convert the outbound encoded data into outbound modulation information; a transmitter section operable to convert the outbound modulation information into an up-converted outbound signal; and a transmit multiplexer operable to:
 couple the up-converted outbound signal to a near field coil antenna structure for inductive coupling to one or more tags in a near field mode; and 
 couple the up-converted outbound signal to a far field antenna structure for RF radio frequency (RF) coupling to the one or more tags in a far field mode. 
 
   
   
   
       18 . The RFID reader of  claim 17 , further comprising:
 a receive multiplexer operable to:
 receive an inbound signal from the near field coil antenna structure when the RFID reader is operating in the near field mode; 
 receive the inbound signal from the far field antenna structure when the reader is operating in the far field mode; and 
 transmit the received inbound signal to a receiver section. 
   
   
   
       19 . The RFID reader of  claim 18 , wherein the receiver section is operable for converting the UHF inbound signal into an encoded inbound signal. 
   
   
       20 . The RFID reader of  claim 19 , wherein the baseband processing module is operable to:
 convert the encoded inbound signal into inbound data using a first encoding protocol when in the near field mode; and   convert the encoded inbound signal into inbound data using a second encoding protocol when in the far field mode.   
   
   
       21 . The RFID reader of  claim 20 , wherein the baseband processing module is operable to:
 convert the outbound data into outbound encoded data using a first encoding protocol when in the near field mode; and   convert the outbound data into outbound encoded data using a second encoding protocol when in the far field mode.   
   
   
       22 . The RFID reader of  claim 21 , wherein the baseband processing module is operable to:
 when the RFID reader is operating in the far field mode, encode a data signal command for transmission in the far field mode to the one or more tags to operate in the near field mode; and   upon receipt of a decoded inbound data from the one or more tags with an acknowledgement of the command, operating the RFID reader in the near field mode.   
   
   
       23 . The RFID reader of  claim 21 , wherein the baseband processing module is operable to:
 when the RFID reader is operating in the near field mode, encode a data signal command for transmission in the near field mode to the one or more tags to operate in the near field mode; and   upon receipt of a decoded inbound data from the one or more tags with an acknowledgement of the command, operating the RFID reader in the far field mode.   
   
   
       24 . The RFID reader of  claim 17 , wherein the transmit multiplexer comprises:
 a first set of transistors coupled to input transistors and the near field antenna coil structure that are operable to couple the up-converted outbound signal to a near field coil antenna structure for inductive coupling to the one or more tags in the near field mode; and   a second set of transistors coupled to the input transistors and the far field antenna structure that are operable to couple the up-converted outbound signal to a far field antenna structure for RF coupling to the one or more tags in the far field mode; and   wherein the transmitter section is operable to signal the transmit multiplexer to activate the first set of transistors to transmit in the near field mode and to signal the transmit multiplexer to activate the second set of transistors to operate in the far field mode.   
   
   
       25 . The multi-mode RFID reader of  claim 17 , wherein the up-converted outbound signal is in an ultra-high frequency (UHF) range in the near field mode and the far field mode.