Cascaded Noise Figure Calculator
Enter the known values and run the calculation.
Overview
Estimate total gain and cascaded noise figure for a multi-stage RF chain.
This tool applies the Friis cascade relationship to a multi-stage RF chain and returns total gain and total noise figure.
Use it for receiver planning, front-end trade studies, and explaining why the first active stage usually dominates the overall noise figure.
The math and how it's used
Each stage is converted from dB into linear gain and linear noise factor.
Total noise factor is then F1 + (F2 - 1)/G1 + (F3 - 1)/(G1 * G2) + ..., and the result is converted back into dB.
This applies Friis cascade math so you can see how the early gain and noise figure terms dominate the total receiver chain.
It is most useful when ordering LNAs, filters, mixers, and gain blocks, or when explaining why a good downstream stage cannot undo a noisy front end.
What to watch
This is only as good as the stage data you enter. Passive loss ahead of the first low-noise stage often hurts far more than people expect.
Gain compression, mismatch, and real filter behavior are outside the model and still matter in a built system.