Reducing receiver performance degradation due to frequency coexistence
First Claim
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1. An apparatus, comprising:
- an antenna for receiving frequency modulated (FM) signals at a first frequency;
a tuning capacitor coupled to the antenna for lowering a capacitance of the antenna;
a resonant filter comprising a low noise amplifier (LNA) tuning inductor coupled to a second capacitor; and
a variable capacitor coupled to the resonant filter, wherein the resonant filter, variable capacitor, and the tuning capacitor are configured to;
tune the antenna to desired frequencies, including the first frequency, andprevent in-band interference by filtering out a near-field communication (NFC) signal at a second frequency mixed with a blocking signal associated with the first frequency.
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Abstract
Systems and apparatuses are provided for negating the degradation effects of fundamental coupling between at least two near field communication (NFC) enabled devices, at least one of which can receive frequency modulation (FM) signals. Due to the fundamental coupling, strong NFC signals can mix with blocking signals associated with a desired/tuned-to FM frequency causing degradation in FM receiver performance. By utilizing a notch filter at the front end of the FM receiver, the degradation in FM receiver performance caused by the fundamental coupling phenomenon can be avoided.
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Citations
16 Claims
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1. An apparatus, comprising:
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an antenna for receiving frequency modulated (FM) signals at a first frequency; a tuning capacitor coupled to the antenna for lowering a capacitance of the antenna; a resonant filter comprising a low noise amplifier (LNA) tuning inductor coupled to a second capacitor; and a variable capacitor coupled to the resonant filter, wherein the resonant filter, variable capacitor, and the tuning capacitor are configured to; tune the antenna to desired frequencies, including the first frequency, and prevent in-band interference by filtering out a near-field communication (NFC) signal at a second frequency mixed with a blocking signal associated with the first frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus, comprising:
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a near-field communication (NFC) antenna; a NFC transceiver for transmitting and receiving NFC signals; a frequency modulation (FM) antenna; a tuning capacitor coupled to the FM antenna for lowering a capacitance of the FM antenna; a front-end comprising; a FM receiver for receiving signals in an FM frequency band; a notch filter comprising a low noise amplifier (LNA) tuning inductor coupled to a second capacitor; and a variable capacitor coupled to the notch filter, wherein the notch filter, variable capacitor, and the tuning capacitor are configured to; tune the antenna to desired frequencies, including an FM frequency, and prevent in-band interference by filtering out the near-field communication (NFC) signal at a second frequency mixed with a blocking signal associated with the FM frequency. - View Dependent Claims (10, 11, 12, 13)
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14. A system, comprising:
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a first near field communications (NFC) enabled device; and a second NFC enabled device, wherein the second NFC enabled device comprises; a NFC antenna; a NFC transceiver for transmitting and receiving NFC signals to and from the first NFC enabled device; a frequency modulation (FM) antenna; a tuning capacitor coupled to the FM antenna for lowering a capacitance of the FM antenna; and a front-end comprising; a FM receiver for receiving signals in an FM frequency band; a notch filter comprising a LNA tuning inductor coupled to a second capacitor; and a variable capacitor coupled to the notch filter, wherein the notch filter, variable capacitor, and the tuning capacitor are configured to; tune the antenna to desired frequencies, including the FM frequency, and prevent in-band interference by filtering out the near-field communication (NFC) signal at a second frequency mixed with a blocking signal associated with the FM frequency. - View Dependent Claims (15, 16)
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Specification