noisefigure

Receiver system noise figure of cascaded stages

Syntax

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

Description

example

````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.```

Examples

collapse all

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

collapse all

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

collapse all

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.