Noise Figure Calculator

Find the noise figure from input and output SNR.

Noise figure (dB) 3

Formula: NF = SNR_in − SNR_out

Step-by-step with your numbers:

1. Values used:

2. Input SNR = 40 dB

3. Output SNR = 37 dB

5. Noise figure = Input SNR - Output SNR = 40 - 37 = 3dB

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Noise figure measures how much a component degrades the signal-to-noise ratio.

The math behind it

In decibels, NF = SNR_in − SNR_out. A perfect, noiseless device has NF = 0 dB.

40 dB in, 37 dB out → NF = 3 dB.

Why minimize the first stage's NF?

Early-stage noise dominates the whole chain (Friis's formula).