Re: [Ngspice-users] Fluctuating white-noise current source

[Holger V. <hol...@un...>]

Michele Giugliano schrieb:
> Dear All,
>
> In the context of  **TRANSIENT** spice simulations, I would like to 
> inject a fluctuating waveform by a some kind of current source, 
> producing a fluctuating current defined as in an Ornstein-Uhlenbeck noise.
>
> This is basically a gaussian white-noise filtered by an RC filter. As a 
> consequence, a "white-noise generator" would be the best for me.
>
> Can someone point me towards the right resources and examples ?
>
> Thanks in advance
> Michele
>
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Dear Michele,

attached you will find a patch to the VSRC voltage source (to be found 
in /src/spicelib/devices/vsrc of ng-spice-rework-17).

This patch will install a new option to the vsrc voltage source offering 
gaussian white noise for transient simulation.

The command to involve noise with voltage source is
VNoi 1 0 DC 0 NOISE(20n 0.5n 0 0)
(see new_noise_test.cir).

In NOISE(NA NT NCF NS) NA is the amplitude, NT is the time between 
sample values (may be overriden by TSTEP from the .TRAN TSTEP TSTOP 
command , CF and NS may later be used for 1/f noise (not yet implemented).

Some theoretical input is still needed to get the correlation between 
NA, NT and the spectral density of the noise voltage. Testing of this 
option in circuits is needed as well. The impelementation of noise into 
the current source isrc is straighforward. I will try to figure out how 
1/f noise may be handled.

Please report some results on this option.

Regards

Holger



Regards

Holger