Methods and apparatus to perform signal removal in a low intermediate frequency receiver
AssigneeTexas Instruments Incorporated
InventorsKhurram Muhammad, Imtinan Elahi
Life of this patent
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Abstract
Methods, apparatus, and articles of manufacture are disclosed for removing an undesired component from a low intermediate frequency signal having an intermediate center frequency and an undesired component at a first frequency. One example method may include determining an amplitude of the undesired component; frequency shifting the low intermediate frequency signal from the intermediate center frequency to produce a zero intermediate frequency signal; filtering the zero intermediate frequency signal; generating a tone based on the amplitude of the undesired component; and subtracting the tone from the filtered zero intermediate frequency signal to remove the undesired component.
Claims23
A method of removing an undesired frequency component from an intermediate frequency signal having an intermediate center frequency, the method comprising:
- frequency shifting the intermediate frequency signal to a zero-intermediate frequency signal having the undesired frequency component at a first frequency;
- filtering the zero-intermediate frequency signal to produce a filtered zero-intermediate frequency signal having the undesired frequency component at the first frequency;
- frequency shifting the filtered zero-intermediate frequency signal to produce a filtered intermediate frequency signal having the undesired frequency component at a second frequency;
- determining an amplitude of the undesired frequency component in the filtered intermediate frequency signal;
- generating a canceling signal at the first frequency based on the amplitude of the undesired frequency component;
- and
- subtracting the canceling signal from the filtered zero-intermediate frequency signal to remove the undesired frequency component.
An article of manufacture comprising a tangible machine-readable medium storing a plurality of computer executable instructions that, when executed, cause a computer to:
- frequency shift the intermediate frequency signal to a zero-intermediate frequency signal having the undesired frequency component at a first frequency;
- filter the zero-intermediate frequency signal to produce a filtered zero-intermediate frequency signal having the undesired frequency component at the first frequency;
- frequency shift the filtered zero-intermediate frequency signal to produce a filtered intermediate frequency signal having the undesired frequency component at a second frequency;
- determine an amplitude of an undesired frequency component in the filtered intermediate frequency signal;
- generate a canceling signal at the first frequency based on the amplitude of the undesired frequency component;
- and
- subtract the canceling signal from the filtered zero-intermediate frequency signal to remove the undesired frequency component.
An apparatus to remove an undesired frequency component from an intermediate frequency signal having an intermediate center frequency, comprising:
- a first mixer to frequency shift the intermediate frequency signal to move the undesired frequency component from a first frequency to a second frequency, thereby creating a zero-intermediate frequency signal;
- a filter coupled to the first mixer to filter the zero-intermediate frequency signal;
- a second mixer to frequency shift the filtered frequency shifted intermediate frequency signal to move the undesired frequency component from the second frequency to the first frequency, thereby creating a filtered intermediate frequency signal;
- a residual offset calculator coupled to an output of the second mixer, wherein an output of the residual offset calculator is processed to determine an amplitude of the undesired frequency component;
- a third mixer to generate a canceling signal at the second frequency based on the amplitude of the undesired frequency component;
- and
- a subtractor to subtract the canceling signal from the filtered zero-intermediate frequency signal to remove the undesired frequency component.
Dependencies are inferred from the claim text.