Tracking filter for a receiver
First Claim
1. An apparatus for communication, comprising:
- a summer to receive an input signal and a feedback signal and provide a first signal;
a downconverter to frequency downconvert a second signal derived based on the first signal and provide an output signal at the output of a receive path of the apparatus;
a filter to filter the output signal and provide a third signal; and
an upconverter to frequency upconvert the third signal and provide a fourth signal from which the feedback signal is derived, where the summer, the filter and the upconverter form a tracking filter.
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Accused Products
Abstract
A tracking filter for attenuating out-of-band signals and adjacent channel signals in a receiver is described. In one exemplary design, an apparatus includes a tracking filter, an LNA, and a downconverter. The tracking filter includes a summer, a filter, and an upconverter. The summer subtracts a feedback signal from an input signal and provides a first signal. The LNA amplifies the first signal and provides a second signal. The downconverter frequency downconverts the second signal and provides an output signal. The filter filters (e.g., differentiates) the output signal and provides a third signal. The filter blocks a desired signal and passes out-of-band signal components. The upconverter frequency upconverts the third signal and provides a fourth signal from which the feedback signal is derived. The tracking filter has an equivalent bandpass filter response and a variable center frequency determined based on the frequency of the desired signal.
42 Citations
23 Claims
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1. An apparatus for communication, comprising:
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a summer to receive an input signal and a feedback signal and provide a first signal; a downconverter to frequency downconvert a second signal derived based on the first signal and provide an output signal at the output of a receive path of the apparatus; a filter to filter the output signal and provide a third signal; and an upconverter to frequency upconvert the third signal and provide a fourth signal from which the feedback signal is derived, where the summer, the filter and the upconverter form a tracking filter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An integrated circuit comprising:
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a summer to receive an input signal and a feedback signal and provide a first signal; a downconverter to frequency downconvert a second signal derived based on the first signal and provide an output signal at the output of a receive path of the integrated circuit; a filter to filter the output signal and provide a third signal; and an upconverter to frequency upconvert the third signal and provide a fourth signal from which the feedback signal is derived, where the summer, the filter and the upconverter form a tracking filter. - View Dependent Claims (16, 17)
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18. A method of filtering an input signal having unwanted frequencies at a receive path, comprising:
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subtracting a feedback signal from the input signal to obtain a first signal; downconverting a second signal based on the first signal to obtain an output signal at the output of the receive path; filtering the output signal to obtain a third signal; upconverting the third signal to obtain a fourth signal; and forming the feedback signal based on the fourth signal, where the feedback signal is used to remove the unwanted frequencies. - View Dependent Claims (19, 20)
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21. An apparatus for communication, comprising:
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means for subtracting a feedback signal from an input signal to obtain a first signal; means for downconverting a second signal derived based on the first signal to obtain an output signal at the output of a receive path of the apparatus; means for filtering the output signal to obtain a third signal; means for upconverting the third signal to obtain a fourth signal; and means for deriving the feedback signal based on the fourth signal, where the means for subtracting, the means for filtering, the means for upconverting and the means for deriving form a tracking filter. - View Dependent Claims (22, 23)
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Specification