Receiver apparatus having filters implemented using frequency translation techniques
First Claim
1. An apparatus, comprising:
- a first mixer configured to frequency translate a first communications signal to a first frequency using a first local oscillator signal to provide a second communications signal;
a filter module configured to filter the second communications signal to provide a third communications signal; and
a second mixer configured to frequency translate the third communications signal to a second frequency using a second local oscillator signal to provide a fourth communications signal,wherein the filter module is characterized by a first center frequency and a first frequency bandwidth corresponding to the first frequency, the second mixer being further configured to effectively frequency translate the first center frequency of the filter module to a second center frequency corresponding to the second frequency while maintaining the first frequency bandwidth.
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Abstract
A method and apparatus is disclosed to effectively frequency translate a filter characterized as a low quality factor (Q) filter, corresponding to a baseband frequency of approximately zero Hertz or to an intermediate frequency (IF), to a filter characterized as a high Q filter at frequencies greater than the baseband frequency or the IF. A downconversion mixer frequency translates a communication signal to the baseband frequency or the IF using a first local oscillator signal to provide a downconverted communication signal. A filter corresponding to the baseband frequency or the IF filters the downconverted communication signal to provide a filtered communication signal. An upconversion mixer frequency translates a communication signal using a second local oscillator signal. The frequency translation by the upconversion mixer, in effect, translates the filter characterization from the low Q filter to the high Q filter at frequencies greater than the baseband frequency or the IF.
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Citations
20 Claims
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1. An apparatus, comprising:
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a first mixer configured to frequency translate a first communications signal to a first frequency using a first local oscillator signal to provide a second communications signal; a filter module configured to filter the second communications signal to provide a third communications signal; and a second mixer configured to frequency translate the third communications signal to a second frequency using a second local oscillator signal to provide a fourth communications signal, wherein the filter module is characterized by a first center frequency and a first frequency bandwidth corresponding to the first frequency, the second mixer being further configured to effectively frequency translate the first center frequency of the filter module to a second center frequency corresponding to the second frequency while maintaining the first frequency bandwidth. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for reducing noise in a received communications signal, comprising:
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a combination module configured to combine the received communications signal and an upconverted replica noise signal to provide a noise reduced communications signal; a first mixer configured to frequency translate the noise reduced communications signal to a first frequency using a first local oscillator signal to provide a recovered communications signal; a filter module configured to filter the recovered communications signal to provide a replica noise signal; and a second mixer configured to frequency translate the replica noise signal to a second frequency using a second local oscillator signal to provide the upconverted replica noise signal, wherein the filter module is characterized by a first center frequency and a first frequency bandwidth corresponding to the first frequency, the second mixer being configured to effectively frequency translate the first center frequency of the filter module to a second center frequency corresponding to the second frequency while maintaining the first frequency bandwidth. - View Dependent Claims (11, 12, 13, 14, 15)
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16. An apparatus for reducing noise in a received communications signal, comprising:
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a first combination module configured to combine an in-phase upconverted replica noise signal and a quadrature phase upconverted replica noise signal to provide a combined upconverted replica noise signal; a second combination module configured to combine the received communications signal and the combined upconverted replica noise signal to provide a noise reduced communications signal; a first in-phase mixer configured to frequency translate the noise reduced communications signal to a first frequency using a first in-phase local oscillator signal to provide an in-phase recovered communications signal; a first quadrature phase mixer configured to frequency translate the noise reduced communications signal to the first frequency using a first quadrature phase local oscillator signal to provide a quadrature phase recovered communications signal; an in-phase filter module configured to filter the in-phase recovered communications signal, to provide an in-phase replica noise signal; a quadrature phase filter module configured to filter the quadrature phase recovered communications signal to provide a quadrature phase replica noise signal; a second in-phase mixer configured to frequency translate the in-phase replica noise signal to a second frequency using a second in-phase local oscillator signal to provide an in-phase upconverted replica noise signal; and a second quadrature phase mixer configured to frequency translate the quadrature phase replica noise signal to the second frequency using a second quadrature phase local oscillator signal to provide a quadrature phase upconverted replica noise signal, wherein the in-phase filter module and the quadrature phase filter module are characterized by a first center frequency and a first frequency bandwidth corresponding to the first frequency, the second in-phase mixer being configured to effectively frequency translate the first center frequency of the in-phase filter module to a second center frequency corresponding to the second frequency while maintaining the first frequency bandwidth, and the second quadrature phase mixer being further configured to effectively frequency translate the first center frequency of the quadrature phase filter module to the second center frequency corresponding to the second frequency while maintaining the first frequency bandwidth. - View Dependent Claims (17, 18, 19, 20)
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Specification