Calculadora de Figura de Ruido — Fórmula

## Friis Noise Figure Formula

### Formula

**F_total = F1 + (F2 - 1)/G1 + (F3 - 1)/(G1 x G2) + ...**

All values in linear (not dB). The first stage dominates overall noise figure. Use a low-noise amplifier (LNA) first for best sensitivity.

Ejemplo Resuelto

LNA (1.5 dB NF, 20 dB gain) followed by mixer (10 dB NF, 15 dB gain) and IF amp (15 dB NF).

  1. F1 = 10^(1.5/10) = 1.413
  2. F2 = 10^(10/10) = 10, G1 = 10^(20/10) = 100
  3. F3 = 10^(15/10) = 31.62, G2 = 10^(15/10) = 31.62
  4. F_total = 1.413 + (10-1)/100 + (31.62-1)/(100x31.62) = 1.413 + 0.09 + 0.0097 = 1.513
  5. NF = 10 x log10(1.513) = 1.80 dB