Receiver architecture for canceling blocking signals

• US 20080009257A1
• Filed: 07/07/2006
• Published: 01/10/2008
• Est. Priority Date: 07/07/2006
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Rofougaran, Ahmadreza (Reza), Safarian, Aminghasem
• Granted Patent: US 7,471,204 B2
• Time in Patent Office: Days
• US Class Current: 455/307
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 5/48 Transceivers
• CPC Class Codes: H04W 4/18 Information format or content conversion, e.g. adaptation by the network of the transmitted or received information for the purpose of wireless delivery to users or terminals
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

A receiver architecture for canceling blocking signals in the receive path includes a low noise amplifier for receiving and amplifying an inbound RF signal to produce an amplified inbound signal, in which the inbound RF signal includes a modulated RF signal and a blocking signal, and a cancellation module for substantially canceling the blocking signal from the amplified inbound RF signal and substantially passing the modulated RF signal. The cancellation module cancels the blocking signal by generating an injection signal representative of the blocking signal, combining the blocking signal with the injection signal to produce an error signal, updating the injection signal based on the error signal and using the injection signal to cancel the blocking signal from the amplified inbound RF signal.

Claims

1. A receiver within a wireless communication device for use in a wireless communication system, comprising:

a low noise amplifier coupled to amplify an inbound RF signal to produce an amplified inbound signal, the inbound RF signal including a modulated RF signal and a blocking signal;

a cancellation module coupled to generate an injection signal representative of the blocking signal, to combine the blocking signal with the injection signal to produce an error signal, to update the injection signal based on the error signal and to substantially cancel the blocking signal from the amplified inbound RF signal and substantially pass the modulated RF signal using the injection signal;

a down-conversion module coupled to convert the modulated RF signal to a near baseband signal;

a digitizing module coupled to convert the near baseband signal into a digital baseband signal; and

a processing module coupled to convert the digital baseband signal into inbound digital symbols.

2. The receiver of claim 1, wherein the cancellation module includes:

an update module coupled to generate the injection signal based on the error signal;

an injection module coupled to receive the blocking signal and the injection signal and to combine the blocking signal with the injection signal to produce a modified RF signal including the modulated RF signal and a modified blocking signal; and

a feedback loop coupled to provide the modified blocking signal as the error signal to the update module for use by the update module in updating the injection signal;

wherein the feedback loop is operable to minimize the modified blocking signal, thereby substantially canceling the blocking signal from the amplified inbound RF signal and substantially passing the modulated RF signal.

3. The receiver of claim 2, wherein the cancellation module further includes:

a receiver signal strength indicator (RSSI) coupled to receive the amplified inbound RF signal and to produce an RSSI signal indicative of the signal strength of the blocking signal; and

a controller coupled to receive the RSSI signal and to produce the error signal from the RSSI signal;

wherein the update module is coupled to receive the injection signal and the error signal and to update the injection signal from the error signal.

4. The receiver of claim 3, wherein the update module is further coupled to receive an outbound RF signal from a transmitter within the wireless communication device as the injection signal.

5. The receiver of claim 4, wherein the update module includes a modulator for updating the injection signal from the error signal and the outbound RF signal.

6. The receiver of claim 5, wherein the cancellation module further includes:

a quadrature generator coupled to receive the outbound RF signal from the transmitter and to generate in-phase and quadrature-phase components from the outbound RF signal for input to the modulator as the injection signal;

wherein the modulator modifies the in-phase and quadrature-phase components using the error signal to update the injection signal.

7. The receiver of claim 4, wherein the update module includes:

a variable gain amplifier coupled to receive an amplitude component of the error signal and the outbound RF signal from the transmitter and to modify an amplitude of the outbound RF signal from the amplitude component to produce a modified RF signal; and

a phase shifter coupled to receive a phase component of the error signal and the modified RF signal and to shift a phase of the modified RF signal from the phase component to update the injection signal.

8. The receiver of claim 3, wherein the cancellation module further includes:

an additional receiver signal strength indicator (RSSI) coupled to receive the inbound RF signal and to produce an additional RSSI signal indicative of the signal strength of the blocking signal;

wherein the controller is coupled to receive both the RSSI signal and the additional RSSI signal and to produce the error signal from the RSSI signal and the additional RSSI signal.

9. The receiver of claim 8, wherein the update module further includes:

a current source coupled to receive the error signal and to produce a bias current from the error signal; and

a limiter coupled to the low noise amplifier and coupled to receive the inbound RF signal and to generate the injection signal from the inbound RF signal;

wherein the limiter is controlled by the bias current to adjust an amplitude of the injection signal to substantially cancel the blocking signal from the amplified inbound RF signal.

10. The receiver of claim 2, wherein the feedback loop is an analog feedback loop and wherein the update module further includes:

a current source coupled to receive the error signal from the analog feedback loop and to produce a bias current from the error signal; and

a limiter coupled to the low noise amplifier and coupled to receive the inbound RF signal, and to generate the injection signal from the inbound RF signal;

wherein the limiter is controlled by the bias current to adjust an amplitude of the injection signal to substantially cancel the blocking signal from the amplified inbound RF signal.

11. The receiver of claim 2, wherein the injection module is a voltage injection module coupled to receive the inbound RF signal and to combine the inbound RF signal with the injection signal.

12. The receiver of claim 2, wherein the injection module is a current injection module coupled to receive the amplified inbound RF signal and to combine the amplified inbound RF signal with the injection signal.

13. The receiver of claim 2, wherein the feedback loop includes:

in-phase and quadrature-phase mixers coupled to receive the amplified inbound RF signal and to down-convert the amplifier inbound RF signal to produce in-phase and quadrature-phase signals indicative of the signal strength of the blocking signal;

in-phase and quadrature-phase low pass filters coupled to receive the in-phase and quadrature-phase signals, respectively, and to filter the in-phase and quadrature-phase signals to produce in-phase and quadrature-phase leakage signals, respectively; and

a controller coupled to receive the in-phase and quadrature-phase leakage signals and to produce the error signal therefrom;

wherein the update module is coupled to receive an outbound RF signal from a transmitter within the wireless communication device as the injection signal, and wherein the update module includes a modulator for updating the injection signal from the error signal and the outbound RF signal.

14. The receiver of claim 13, wherein the cancellation module further includes:

a quadrature generator coupled to receive the outbound RF signal from the transmitter and to generate in-phase and quadrature-phase components from the outbound RF signal for input to the modulator as the injection signal;

wherein the modulator modifies the in-phase and quadrature-phase components using the error signal to update the injection signal.

15. The receiver of claim 14, wherein the receiver is a wide band code division multiple access (WCDMA) receiver implemented on a transceiver integrated circuit of a WCDMA transceiver.

16. The receiver of claim 1, wherein the receiver is a radio frequency identification (RFID) receiver within an RFID reader, and wherein the blocking signal has a frequency substantially similar to a frequency of the modulated RF signal.

17. The receiver of claim 1, wherein the blocking signal includes a leakage signal produced from leakage of an outbound RF signal generated by a transmitter into the receiver.

18. The receiver of claim 17, wherein the blocking signal further includes a reflected signal produced from reflection of the outbound RF signal.

19. A method for canceling a blocking signal at a receiver, comprising:

receiving an inbound RF signal including a modulated RF signal and the blocking signal;

generating an injection signal representative of the blocking signal;

combining the blocking signal with the injection signal to produce an error signal;

updating the injection signal based on the error signal; and

canceling the blocking signal from the inbound RF signal to pass the modulated RF signal using the injection signal.

20. A method for operating a receiver, comprising:

receiving an inbound RF signal including a modulated RF signal and a blocking signal;

amplifying the inbound RF signal to produce an amplified inbound RF signal;

generating an injection signal representative of the blocking signal;

combining the blocking signal with the injection signal to produce an error signal;

updating the injection signal based on the error signal;

canceling the blocking signal from the amplified inbound RF signal to pass the modulated RF signal using the injection signal;

converting the modulated RF signal to a near baseband signal;

converting the near baseband signal into a digital baseband signal; and

converting the digital baseband signal into inbound digital symbols.