WIRELESS RECEIVER WITH NOTCH FILTER TO REDUCE EFFECTS OF TRANSMIT SIGNAL LEAKAGE
First Claim
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1. A radio frequency (RF) receiver comprising:
- an amplifier that amplifies a received RF input signal comprising a desired signal and a transmit leakage signal;
a mixer that down-converts a frequency of the amplified signal; and
a notch filter that filters the down-converted signal to substantially reduce the down-converted transmit leakage signal.
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Abstract
This disclosure describes techniques for reducing adverse effects of TX signal leakage in a full-duplex, wireless communication device. The techniques make use of a notch filter to reject TX signal leakage in a signal processed in the RX path of the wireless communication device. The notch filter may be constructed as a complex notch filter using passive resistor and capacitor components to produce a notch frequency that attenuates TX signal leakage components in a desired signal. The notch filter may be applied to a down-converted, baseband signal produced by a passive mixer.
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Citations
36 Claims
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1. A radio frequency (RF) receiver comprising:
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an amplifier that amplifies a received RF input signal comprising a desired signal and a transmit leakage signal; a mixer that down-converts a frequency of the amplified signal; and a notch filter that filters the down-converted signal to substantially reduce the down-converted transmit leakage signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A notch filter for a radio frequency (RF) receiver, the notch filter comprising:
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a first resistor coupled between a positive in-phase (I) input and a positive I output; a second resistor coupled between a negative I input and a negative I output; a third resistor coupled between a positive quadrature (Q) input and a positive Q output; a fourth resistor coupled between a negative Q input and a negative Q output; a first capacitor coupled between the positive I input and the positive Q output; a second capacitor coupled between the negative I input and the negative Q output; a third capacitor coupled between the positive Q input and the negative I output; and a fourth capacitor coupled between the negative Q input and the positive I output, wherein the resistor and capacitor values are selected to substantially reduce a down-converted transmit leakage signal in an input signal applied at the inputs. - View Dependent Claims (13, 14, 15)
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16. A wireless communication device comprising:
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an antenna; a radio frequency (RF) transmitter that generates a transmit (TX) signal; a duplexer that couples the TX signal to the antenna; an RF receiver that receives an RF input signal from the antenna via the duplexer, wherein the RF receiver comprises; an amplifier that amplifies the received RF input signal comprising a desired signal and a transmit leakage signal coupled from the duplexer; a mixer that down-converts the amplified signal; and a notch filter that filters the down-converted signal to substantially reduce the down-converted transmit leakage signal. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A method comprising:
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amplifying a received RF input signal comprising a desired signal and a transmit leakage signal; down-converting a frequency of the amplified signal; and filtering the down-converted signal with a notch filter to substantially reduce the down-converted transmit leakage signal. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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Specification