How to draw noise contour plot for transistors

[Stefan Heinzmann]

Hi all,

I was wondering how noise contour plots are generated for transistor
data sheets. Curve tracers do not seem to be capable of this. Is there a
standard measurement setup? Can SPICE (LtSpice preferably) plot it?

Cheers
Stefan

 

[John Woodgate]

I read in sci.electronics.design that Stefan Heinzmann
online.com>) about 'How to draw noise contour plot for transistors', on
Sun, 18 Jan 2004:

I was wondering how noise contour plots are generated for transistor data
sheets. Curve tracers do not seem to be capable of this. Is there a standard
measurement setup?

I don't know about 'standard', but it could be done. It's not trivial,
though.

Can SPICE (LtSpice preferably) plot it?

If you have an accurate model, yes. But you may not have one that is
accurate in terms of the relevant parameters.

 

[Charles DH Williams]

I was wondering how noise contour plots are generated for transistor
data sheets. Curve tracers do not seem to be capable of this. Is there a
standard measurement setup? Can SPICE (LtSpice preferably) plot it?

You need to measure noise density spectra for a number of source impedances,
which spice can do easily. Then you assemble these results in to a
2d matrix. This can anywhere from easy to impossible depending on the
version of spice you use. Then you need a contour plot of this matrix.
I don't know any spice that will do this directly, but plenty
of other packages (e.g. MatLab) do it, no problem.

Charles

 

[Jim Thompson]

Hi all,

I was wondering how noise contour plots are generated for transistor
data sheets. Curve tracers do not seem to be capable of this. Is there a
standard measurement setup? Can SPICE (LtSpice preferably) plot it?

Cheers
Stefan

PSpice can do it in a "Performance Analysis".

...Jim Thompson