11/24/2002
Noise: An Introduction
20
Thermal Noise (2)
•A more accurate model
(Quantum Theory)
Which corrects for the high frequency roll off
(above 4000 GHz at room temperature)
(above 4000 GHz at room temperature)
•The power in the noise
is simply
Pn = k*T*BW Watts or
Pn = -174 + 10*log10(BW) in dBm
(decibels relative to a milliwatt)
(decibels relative to a milliwatt)
Note: dB = 10*log10 (P/Pref ) =
20*log10 (V/Vref )
