Nosie Figure Calculator

NF = noise figure of stage N (dB)

Gain = gain of stage N (dB)

N = # of cascade stages

NF (db)

Gain (db)

Results

Total NF : ??????

Total Gain : ??????

Noise Temp : ??????

Description

Noise figure shows how the the signal to noise ratio (SNR) is degraded by a device/system. The total noise factor attributed to the noise contribution of each stage in a cascade follow the Friis equation:

where nf_N and g_N is the linear noise figure and linear gain, respectively of stage N. Noise figure is noise factor expressed in decibels (dB). The noise factor equation shows that stage 1 has the most influence in the overal noise factor/figure of a system. As a result, to reduce the total noise figure the first stage device should have low-noise and relatively high gain. This is why a low-noise amplifier (LNA) is the first active device in a communications system.

Use the EM Talk noise figure calculator to determine the overall noise figure for a cascaded N-stage amplifier/system. The number of stages can range from 2 to 30 stages. No need to download an excel sheet to do your noise figure calculations!

How To Use

First, select the number of stages for your cascade. Then, enter in the noise figure (NF) and gain for each stage in dB. Press Calculate to determine the total noise figure, total gain and the noise temperature for your cascade.