Environmental Engineering Reference
In-Depth Information
As an illustration, consider a resistor
R
with one-sided power spectral
density where is Boltzmann constant and
T
is the absolute temperature in degrees Kelvin. Let the equivalent noise
bandwidth of the circuit in which
R
resides be The step
size used in representation of the thermal noise of the resistor in the time-
domain is given by Nyquist theorem
seconds and the
total noise power of the resistor is calculated from
The time-domain noise waveform of the resistor is shown in Fig.6.7.
The power spectral density of the thermal noise of the resistor is ob-
tained by performing FFT on its time domain wave form. The spectrum
of the thermal noise of the resistor with 512 samples is shown in Fig.6.8,
the interval between two adjacent frequency samples can be calculated
from
The average of ten sets of data of
the noise waveform has a mean of
and standard deviation of
The averaged power is
For reliable simulation, the
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