Rfid reader with active blocking rejection in receiver

Abstract

An RFID reader is operable to receive an inbound RF signal from an RFID tag during transmission of an outbound RF signal. The inbound RF signal from the RFID tag is a modulated, backscattered signal that includes a desired RF signal component and a blocking RF signal component. The receiver section of the RFID reader includes a preprocessing module operable to process the inbound RF signal. The preprocessing module includes an adjustable attenuation module operable to attenuate the inbound RF signal to produce an attenuated inbound RF signal and an active blocking rejection module operable to increase a ratio of the desired RF signal component to blocking RF signal component in the attenuated inbound RF signal.

1 . A radio frequency identification (RFID) reader, comprising:
 a receiver section that includes:
 a preprocessing module including:
 an attenuation module operable to attenuate an inbound radio frequency (RF) signal having a desired RF signal component and a blocking RF signal component to produce an attenuated inbound RF signal; 
 an active blocking rejection module operable to attenuate the blocking RF signal component in the attenuated inbound RF signal to increase a ratio of the desired RF signal component to the blocking RF signal component in the preprocessed inbound RF signal; 
 
 a down conversion module coupled to convert the preprocessed inbound RF signal into a down converted signal; 
 a post processing module operable to process the down converted signal to generate a desired near baseband signal; and 
 an analog to digital conversion module coupled to convert the desired near baseband signal into an encoded inbound signal. 
   
   
   
       2 . The RFID reader of  claim 1 , wherein the active blocking rejection module comprises:
 a low noise amplifier (LNA) module coupled to amplify the attenuated inbound RF signal to generate an amplified inbound RF signal;   a limiting module operable to limit the desired RF signal component in the attenuated inbound RF signal to generate a limited inbound RF signal; and   a subtraction module operable to subtract the amplified inbound RF signal and limited inbound RF signal to generate the preprocessed inbound RF signal.   
   
   
       3 . The RFID reader of  claim 2 , wherein the limiting module suppresses amplitude modulation of the desired RF signal component to generate the limited inbound RF signal, wherein the limited inbound RF signal includes the blocking RF signal component and a signal residual component. 
   
   
       4 . The RFID reader of  claim 3 , wherein the signal residual component is proportional to a first component of the desired RF signal component not suppressed by the limiting module. 
   
   
       5 . The RFID reader of  claim 4 , wherein the preprocessed inbound RF signal is proportionate to a second component of the desired RF signal and a phase difference between the desired RF signal component and the blocking RF signal component. 
   
   
       6 . The RFID reader of  claim 1 , further comprising:
 a transmitter section that includes:
 an oscillation module coupled to convert a reference oscillation into a radio frequency (RF) oscillation; and 
 a power amplifier module coupled to amplify and to modulate the RF oscillation in accordance with outbound modulation information to produce an outbound RF signal. 
   
   
   
       7 . The RFID reader of  claim 6 , wherein the blocking RF signal component of the attenuated inbound RF signal includes a component of the outbound RF signal. 
   
   
       8 . The RFID reader of  claim 7 , wherein the attenuation module is adjustable. 
   
   
       9 . The RFID reader of  claim 8 , wherein the attenuation module is adjusted in response to a power level of the outbound RF signal to reduce a dynamic range of the inbound RF signal and produce the attenuated inbound RF signal 
   
   
       10 . The RFID reader of  claim 6 , wherein the active blocking rejection module comprises:
 a clock module operable to convert the RF oscillation into an in-phase (I) RF clock signal and a quadrature (Q) RF clock signal;   a multiplexing module operable to output the I RF clock signal or the Q RF clock signal;   a power detection module coupled to determine a power level of the attenuated inbound RF signal;   an adjustable amplifier coupled to amplify the output of the multiplexing module based on the power level of the attenuated inbound RF signal to produce an amplified I or Q RF clock signal;   a summing module coupled to sum the amplified I or Q RF clock signal with the attenuated inbound RF signal to produce a phase adjusted inbound RF signal;   a low noise amplifier module coupled to amplify the phase adjusted inbound RF signal to produce an amplified inbound RF signal;   a limiting module coupled to limit the phase adjusted inbound RF signal to produce a limited inbound RF signal; and   a subtraction module coupled to subtract the limited inbound RF signal from the amplified inbound RF signal to produce the preprocessed inbound RF signal.   
   
   
       11 . The RFID reader of  claim 10 , wherein the summing module is coupled to sum the amplified I or Q RF clock signal with the attenuated inbound RF signal to decrease a phase difference between the desired RF signal component and the blocking RF signal component to produce the phase adjusted inbound RF signal. 
   
   
       12 . The RFID reader of  claim 11 , wherein the preprocessed inbound RF signal has an improved ratio of the desired RF signal component to the blocking RF signal component from the attenuated inbound RF signal. 
   
   
       13 . A transceiver, comprising:
 a transmitter section that includes:
 an oscillation module coupled to convert a reference oscillation into a radio frequency (RF) oscillation; and 
 a power amplifier module coupled to amplify and to modulate the RF oscillation in accordance with outbound modulation information to produce an outbound RF signal. 
   a receiver section that includes:
 a preprocessing module operable to process an inbound RF signal to produce a preprocessed inbound RF signal, wherein the preprocessing module includes:
 an adjustable attenuation module operable to attenuate the inbound RF signal to produce an attenuated inbound RF signal, wherein the attenuated inbound RF signal includes a desired RF signal component and a blocking RF signal component; and 
 an active blocking rejection module operable to adjust a phase of the blocking RF signal component to increase a ratio of the desired RF signal component to blocking RF signal component in the preprocessed inbound RF signal. 
 
   
   
   
       14 . The transceiver of  claim 13 , wherein the active blocking rejection module comprises:
 a clock module operable to convert the RF oscillation into an in-phase (I) RF clock signal and a quadrature (Q) RF clock signal;   a multiplexing module operable to select and output the I RF clock signal or the Q RF clock signal;   a power detection module coupled to determine a power level of the attenuated inbound RF signal;   an adjustable amplifier coupled to amplify the output of the multiplexing module based on the power level of the attenuated inbound RF signal to produce an amplified I or Q RF clock signal;   a summing module coupled to sum the amplified I or Q RF clock signal with the attenuated inbound RF signal to adjust the phase of the blocking RF signal component to produce a phase adjusted inbound RF signal.   
   
   
       15 . The transceiver of  claim 14 , wherein the active blocking rejection module, further comprises:
 a low noise amplifier (LNA) module coupled to receive the phase adjusted inbound RF signal and operable to amplify the phase adjusted inbound RF signal to generate an amplified inbound RF signal;   a limiting module coupled to limit the phase adjusted inbound RF signal to generate a limited inbound RF signal; and   a subtraction module coupled to the LNA module and limiting module and operable to subtract the amplified inbound RF signal and limited inbound RF signal to increase the ratio of the desired RF signal component to the blocking RF signal component and to output the preprocessed inbound RF signal.   
   
   
       16 . The transceiver of  claim 15 , further comprising:
 a down conversion module coupled to receive the preprocessed inbound RF signal and produce a down converted signal;   a post processing module operable to process the down converted signal to generate a desired near baseband signal; and   an analog to digital conversion module coupled to convert the desired near baseband signal into an encoded inbound signal.   
   
   
       17 . The transceiver of  claim 16 , further comprising:
 a baseband processing module operable to:
 convert outbound data into the outbound modulation information; and 
 convert the encoded inbound signal into inbound data. 
   
   
   
       18 . A transceiver, comprising:
 a transmitter section that includes:
 an oscillation module coupled to convert a reference oscillation into a radio frequency (RF) oscillation; and 
 a power amplifier module coupled to amplify and to modulate the RF oscillation in accordance with outbound modulation information to produce an outbound RF signal. 
   a preprocessing module that includes:
 an adjustable attenuation module operable to attenuate an inbound RF signal in response to a power level of the outbound RF signal to reduce a dynamic range of the inbound RF signal and produce an attenuated inbound RF signal, wherein the attenuated inbound RF signal includes a desired RF signal component and a blocking RF signal component; and 
 an active blocking rejection module operable to substantially attenuate the blocking RF signal component of the attenuated inbound RF signal to produce a preprocessed inbound RF signal. 
   
   
   
       19 . The transceiver of  claim 18 , wherein the active blocking rejection module comprises:
 a low noise amplifier (LNA) module coupled to receive the attenuated inbound RF signal and operable to amplify the attenuated inbound RF signal to generate an amplified inbound RF signal;   a limiting module coupled to limit the attenuated inbound RF signal to generate a limited inbound RF signal; and   a subtraction module coupled to subtract the limited inbound RF signal from the amplified inbound RF signal to generate the preprocessed inbound RF signal.   
   
   
       20 . The transceiver of  claim 19 , wherein the limiting module suppresses amplitude modulation of the desired RF signal component to generate the limited inbound RF signal, wherein the limited inbound RF signal includes the blocking RF signal component and a signal residual component proportional to a first component of the desired RF signal component not suppressed by the limiting module.