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Cascaded Noise Figure Calculator (Friis Formula)

Calculate total system noise figure for cascaded RF stages using the Friis formula. Enter NF and gain for each stage to get system NF and receiver sensitivity.

Interactive Cascade NF Calculator

Cascaded Noise Figure (up to 4 stages)

System NF
Total Gain
Receiver Sensitivity

Friis Formula Reference

  F_total = F₁ + (F₂−1)/G₁ + (F₃−1)/(G₁G₂) + (F₄−1)/(G₁G₂G₃)

  Key insight: High first-stage gain G₁ suppresses all later noise.
  Sensitivity = −174 + NF_sys + 10·log₁₀(BW_Hz) + SNR_min  [dBm]
RF View: Analyze LNA gain (S21) and matching (S11) to optimize the first stage of your receive chain — the most critical factor in system noise figure. Free on Android.

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