5.4 T
HERMAL
NOISE
5.4.1 S
IMULATION
OF
THE
NOISE
VOLTAGE
IN
QUCS
In order to get an idea about the expected noise of the resonance circuit, its voltage noise was
simulated by qucs (
Q
uite
U
niversal
C
ircuit
S
imulator) not connecting anything to the input, but
analysing the output noise using the AC-simulation feature of qucs.
The result of the ac-simulation is then plotted in a diagram and shows the noise voltage (extension
.nv) to be higher around the resonance of this circuit:
According to this, the peak noise of this resonance circuit should be 25 nV/sqrt(Hz).
Manual Anfatec PCI-Lockin Amplifier AMU2.4 – Rev. 1.10 dated 30/09/20
Page 26 (70)
Figure 20: How to calculate noise voltage in qucs
Figure 21: Change simulation properties
Figure 22: Diagram with noise voltage of the resonance circuit.
Figure 19: qucs/Noise_voltage.sch
