PUISSANCE DE BRUIT & FACTEUR DE BRUIT

N(W) =

k.T.B

N(dBm) =

10.log(k.300.1e3) = -174dBm

à T=300°K (soit 27°C) et B=1Hz.

N(dBm) =

-174+10.log(B.1e3)

à T=300°K

T :

Noise's temperature (K)

B :

Bandpass (Hz)

k :

Boltzmann's constant

k= 1,3807E-23 J/K

F= Ns / (G.Ne) (F>1)

Ns= G.Ne + (F-1).G.Ne

Ns= F.G.Ne

N1= G1.Ne + (F1-1).G1.Ne

N2= G2.N1 + (F2-1).G2.Ne

N2= G1.G2.Ne + (Fa-1).G1.G2.Ne 

For Gain and Noise terms used linears terms and not dB !

Teq represents the equivalent temperature of noise for an ideal amplifier G ; and To is the thermal noise.
Ns= G.(k.To.B+k.Teq.B) = G.k.B.(To+Teq) = F.G.Ne = F.G.k.To.B

  
Compute Teq for amplifiers {F1,G1} and {F2,G2} with Teq1 and Teq2.