This section contains all stuff related to AC Noise calculation in Gnucap.
Currently (April 2011) noise is implemented in experimental branch and work as plugin. Please see Code-related Stuff for more details.
Noise is claculated using adjacent system method [TBD GS - complete, explain ]
To run noise simulation - ad the following line to circuit file (spice format):
.noise V(a,b) Dev stepmode points fromF toF
V(a) is the same as V(a,0)
It will calculate noise power density between output nodes “a” and “b” and equivalent power at input device “Dev” using “stepmode” making “points” in frequency range “fromF”-“toF”
.noise v(3) V1 oct 5 10 10K
- calcualate spectral noise density at node “3” and reduce it to input device V1 making 5 points per octave in frequency range from 10HZ to 10KHZ
.noise V(10,12) I1 dec 2 10K 10MEG
- calcualate spectral noise density between nodes 10 and 12 and reduce it to input device I1 making 2 points per decade in frequency range from 10KHZ to 10MHZ
Usually simulators also support
.print noise statement. Now it is not implemented yet.
Currently output contains:
Freq inoise_density onoise_density
Also - at the end of the frequency range total power over the range s integrated:
Currently noise simulation is implemented as plugin which is available at github at the following link
It re-uses s_ac.cc file (ac simulation) to implement noise analysis.
At the present moment (April 2011) noise works with only gnucap-a branch of gnucap, but hopefully soon it will work with main trunk too.
[TBD - make description of the noise code]