Noise Measurements

Unlock the full potential of your devices with Noise Measurement. Determine the four Noise Parameters of your transistor to understand its noise behavior at a given frequency, enabling precise optimization for enhanced performance.

Applications Hero Background


Noise measurements allow the determination of the four Noise Parameters of a device (transistor).  There are four Noise Parameters which fully describe the noise behavior of an active or passive device at a given frequency.

The Noise Parameters are not load depended, they are only affected by Source Impedance. There exist a simple relation between the four Noise Parameters:

NF calculation formula is the following:

  • NFLinear = NFMinLinear + ((4 * Rn / Zo) * (Gs – GammaOpt).Mag2 ) / ((1 + GammaOpt).Mag2 * (1 – Gs.Mag2));

This is the equation of a set of isometric circles on the Smith Chart (Noise Circles) for which the value of the Noise Figure is the Level on each circle. This Circle Representation is only possible because the Noise behavior of transistors is a Small Signal Phenomenon.


  • NFminLinear is the minimum noise figure in linear.
  • Rn is the equivalent noise resistance in Ohms
  • Gs is the gamma presented to the DUT at the input (in our case by the tuner).
  •  GammaOpt is the optimum gamma (i.e.: gamma source for which the DUT produces the minimum noise figure).
    • Note: Mag2 denotes the magnitude squared.






Noise Parameters

Noise Circles & Stability Regions

Noise Parameters: Minimum Noise Figure / Rn / Gamma Opt / Phase of Gamma Opt


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