Noise measurements allow the determination of the four Noise Parameters of a device (transistor).

Noise Parameters: These are four numbers that fully describe the noise behaviour of an active or passive device
(twoport) at a given frequency. For practical reasons we
use the following quantities as Noise Parameters:
• Minimum Noise Figure (Fmin): This is the smallest
Noise Figure that the device can reach at a given
frequency and bias, if it is optimally matched at the
source.
• Equivalent Noise Resistance (Rn): This is a number
with the dimension Ohm that indicates how fast the
Noise Figure increases when we mismatch the input
(source).
• Optimum Noise Reflection Factor (Γopt ), is often used also as Optimum Admittance Yopt: Is the
source admittance required for the DUT to perform
Fmin ; (Yopt=Gopt+jBopt), 2 parameters.
The Noise Figure does not depend on the Load impedance presented to the device . It only depends on the
Source Impedance. There exist a simple relation between
the four Noise Parameters:
Noise Figure F(Ys) = Fmin + (Rn/Gs)*| Ys – Yopt|2
where Ys = Gs +jBs. 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 behaviour of transistors is a Small Signal Phenomenon.

Wideband Noise using Passive Tuners

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Input Noise Module

wdt_ID Model s Frequency Connector Insertion Loss VSWR
1 INM-2600 up to 26.5 GHz 3.5mm 0.80 dB 1.60
2 INM-4000 up to 40 GHz 2.9mm 0.91 dB 1.80
3 INM-5000 up to 50 GHz 2.4mm 0.99 dB 1.80
4 INM-6700 up to 67 GHz 1.85mm 1.12 dB 1.90

Output Noise Module

wdt_ID Model s Frequency Connector Downconverter Minimum Gain (dB) Maximum VSWR
1 ONM-2600 up to 26.5 GHz 3.5mm 29 1.8:1
2 ONM-4000 up to 40 GHz 2.9mm 30 for ≤26.5GHz, 29 for 26-40GHz 2.1:1
3 ONM-4000-DC up to 40 GHz 2.9mm 30 for ≤26.5GHz, 29 for 26-40GHz 2.1:1
4 ONM-5000 up to 50 GHz 2.4mm 27 for ≤26.5GHz, 27 for 26-40GHz, 28 for 40-50GHz 2:1
5 ONM-5000-DC up to 50 GHz 2.4mm 27 for ≤26.5GHz, 27 for 26-40GHz, 28 for 40-50GHz 2:1
6 ONM-6700 up to 67 GHz 1.85mm 29 for ≤26.5GHz, 28.5 for 26-40GHz, 28 for 40-50GHz, 21 for 50-65GHz 3:1
7 ONM-6700-DC up to 67 GHz 1.85mm 29 for ≤26.5GHz, 28.5 for 26-40GHz, 28 for 40-50GHz, 21 for 50-65GHz 3:1

Noise Parameters

Noise Circles & Stability Regions

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

Typical Noise Setup

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