Author Topic: Flicker noise voltage source (LT-SPICE)  (Read 5009 times)

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Offline GuilleTopic starter

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Flicker noise voltage source (LT-SPICE)
« on: February 25, 2024, 06:36:00 pm »
SOLVED

Hi everyone,

I need to simulate a sensor noise floor for which I have the curve, to do this I wanted to create a couple of noise sources that would give me flicker noise and white noise, Section 4-5 in this book: https://pearl-hifi.com/06_Lit_Archive/14_Books_Tech_Papers/Motchenbacher_Connelly/Low-noise_Electronic_Design.pdf  suggested biasing a diode with a DC current source to generate some 1/f current noise, then measuring this current noise with a dummy 0V voltage source (with a 1GF cap decoupling I_DC) and finally using the dummy VS to drive a current dependent voltage source to turn it into voltage. From there it would only be a matter of fitting the Diode variables KF and AF to get the expected level.



However when I perform the .noise analysis all I'm getting is a constant noise spectra fixed at 3.12pV/Hz½, no presence of flicker noise no matter how much I play with the parameters...

* FlickerVoltageNoise_Motchenbacher.asc (0.82 kB - downloaded 31 times.)

I've been at this all day and I cannot get it to work, I tried with a noiseless series resistance to the diode but that gave me a constant 0pV/Hz½. how can I get this to work? Is there some workaround to get a flicker noise voltage in LT-SPICE?

You can find the simulation file "FlickerVoltageNoise_Motchenbacher.asc" in up this post.


Many thanks in advanced.
--
Guille

« Last Edit: February 27, 2024, 04:22:54 pm by Guille »
 

Offline GuilleTopic starter

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  • Country: es
Re: Flicker noise voltage source (LT-SPICE)
« Reply #1 on: February 27, 2024, 04:18:48 pm »
SOLUTION: I needed to change the model directive from change

.MODEL D1 D (KF = 6.408E-17, AF = 1)

to

.MODEL D D (KF = 6.408E-17, AF = 1)

It's working now however if you are in my same position and want tunable noise sources I found the following Github with a couple of models you can use: https://github.com/yildi1337/LTspiceNoiseSources
« Last Edit: February 27, 2024, 04:23:07 pm by Guille »
 


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