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noisefigure

Receiver system noise figure of cascaded stages

Since R2021a

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    Syntax

    cnf = noisefigure(nf,g)
    [cnf,cg] = noisefigure(nf,g)
    [cnf,cg,ctemp] = noisefigure(nf,g,reftemp)

    Description

    cnf = noisefigure(nf,g) returns the scalar noise figure in decibels of the cascaded stages of a receiver system. The vector nf contains the noise figures for the different stages and the vector g contains the gains.

    example

    [cnf,cg] = noisefigure(nf,g) returns the scalar total gain in decibels of the cascaded system.

    example

    [cnf,cg,ctemp] = noisefigure(nf,g,reftemp) specifies the reference temperature in kelvins and returns the noise temperature of the cascaded receiver stages.

    example

    Examples

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    Open Live Script

    Compute the cascaded noise figure and total gain of a receiver system. The system has seven stages, with these values:

    1. LNA with a noise figure of 1.0 dB and a gain of 15.0 dB

    2. RF filter with a noise figure of 0.5 dB and a gain of –0.5 dB

    3. Mixer with a noise figure of 5.0 dB and a gain of –7.0 dB

    4. IF filter with a noise figure of 1.0 dB and a gain of –1.0 dB

    5. IF preamplifier with a noise figure of 0.6 dB and a gain of –15.0 dB

    6. IF stages with a noise figure of 1.0 dB and a gain of 20.0 dB

    7. Phase detectors with a noise figure of 6.0 dB and a gain of –5.0 dB

    nf = [1.0 0.5 5.0 1.0 0.6 1.0 6.0];
g = [15.0 -0.5 -7.0 -1.0 15.0 20.0 -5.0];

[cnf,ng] = noisefigure(nf,g)
    cnf = 
1.5252

    ng = 
36.5000

    Compute the noise temperature of the cascaded receiver stages. Specify the reference temperature as 300 K.

    rtemp = 300;

[~,~,ctemp] = noisefigure(nf,g,rtemp)
    ctemp = 
426.2281

    Input Arguments

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    Stage-by-stage noise figures in decibels, specified as a vector.

    Data Types: double

    Stage-by-stage gains in decibels, specified as a vector.

    Data Types: double

    Reference temperature, specified as a nonnegative scalar in kelvins.

    Data Types: double

    Output Arguments

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    Noise figure of cascaded receiver stages, returned as a scalar in decibels.

    Total gain of cascaded system, returned as a scalar in decibels.

    Noise temperature of cascaded receiver stages, returned as a scalar in kelvins.

    References

    [1] Barton, David K. Radar System Analysis and Modeling. Boston: Artech House, 2005.

    Version History

    Introduced in R2021a

    See Also