Near field RFID system with multiple reader coils

Abstract

A near field RFID system includes an RFID reader and an RFID tag. The RFID reader includes a transmit path and a receive path, wherein the transmit path includes: an encoding section coupled to convert data into encoded data; a digital to analog conversion module coupled to convert the encoded data into an analog encoded signal; a power amplifier coupled to amplify the analog encoded signal; and a plurality of coils coupled to generate a plurality of electromagnetic fields from the analog encoded signal. The RFID tag that includes: a coil coupled to generate a current and a recovered signal from at least one of the plurality of electromagnetic fields; a power recovery circuit coupled to generate a voltage from the current; and a data processing section coupled to process the recovered signal, wherein the data processing section is powered via the voltage.

1 . A radio frequency identification (RFID) system comprises: 
 an RFID reader that includes: 
 an encoding section coupled to convert data into encoded data;  
 a digital to analog conversion module coupled to convert the encoded data into an analog encoded signal;  
 a power amplifier coupled to amplify the analog encoded signal; and  
 a plurality of coils coupled to generate a plurality of electromagnetic fields from the analog encoded signal; and  
   an RFID tag that includes: 
 a coil coupled to generate a current and a recovered signal from at least one of the plurality of electromagnetic fields;  
 a power recovery circuit coupled to generate a voltage from the current; and  
 a data processing section coupled to process the recovered signal, wherein the data processing section is powered via the voltage.  
   
   
   
       2 . The RFID system of  claim 1  comprises: 
 the RFID reader implemented on a first integrated circuit; and    the RFID tag implemented on a second integrated circuit.    
   
   
       3 . The RFID system of  claim 1 , wherein the RFID reader comprises: 
 a coil controller coupled to the plurality of coils, wherein the coil controller enables the plurality of coils in accordance with an electromagnetic field cancellation avoidance scheme.    
   
   
       4 . The RFID system of  claim 3 , wherein the magnetic field cancellation avoidance scheme comprises at least one of: 
 frequency diversity; and    time diversity.    
   
   
       5 . The RFID system of  claim 1 , wherein the coil of the RFID tag comprises: 
 a plurality of traces on a plurality of layers of an integrated circuit.    
   
   
       6 . The RFID system of  claim 1 , wherein the coil of the RFID tag comprises: 
 system parameters for operating as the coil for a near field RFID communication and as an antenna for a far field RFID communication.    
   
   
       7 . A radio frequency identification (RFID) reader comprises: 
 an encoding section coupled to convert data into encoded data;    a digital to analog conversion module coupled to convert the encoded data into an analog encoded signal;    a power amplifier coupled to amplify the analog encoded signal; and    a plurality of coils coupled to generate a plurality of electromagnetic fields from the analog encoded signal.    
   
   
       8 . The RFID reader of  claim 7  further comprises: 
 a coil controller coupled to the plurality of coils, wherein the coil controller enables the plurality of coils in accordance with an electromagnetic field cancellation avoidance scheme.    
   
   
       9 . The RFID reader of  claim 8 , wherein the magnetic field cancellation avoidance scheme comprises at least one of: 
 frequency diversity; and    time diversity.    
   
   
       10 . A radio frequency identification (RFID) tag comprises: 
 a coil coupled to generate a current and a recovered signal from at least one of the plurality of electromagnetic fields;    a power recovery circuit coupled to generate a voltage from the current; and    a data processing section coupled to process the recovered signal, wherein the data processing section is powered via the voltage.    
   
   
       11 . The RFID tag of  claim 10 , wherein the coil comprises: 
 a plurality of traces on a plurality of layers of an integrated circuit.    
   
   
       12 . The RFID tag of  claim 10 , wherein the coil comprises: 
 system parameters for operating as the coil for a near field RFID communication and as an antenna for a far field RFID communication.