please help me about hspice plot noise

i want to use hspice for plot output noise i write : .noise v(vout)
vin dec 10 100meg 3g
though I'm somewhat in doubt as to how to interpret the results.
Basically the
onoise_spectrum had about the shape was about 8.613e-17 v/rt hz
whereas the data sheet listed something
like 9.2809n v/rt hz noise (at the input). What about this?

 

[oliver]

On Jun 27, 10:42 am, egolz...@gmail.com wrote:

i want to use hspice for plot output noise i write : .noise v(vout)
vin dec 10 100meg 3g
though I'm  somewhat in doubt as to how to interpret the results.
Basically the
 onoise_spectrum had about the shape  was about 8.613e-17  v/rt hz
whereas the data sheet listed something
 like  9.2809n v/rt hz noise (at the input).  What about this?

It seems the plotted output noise was in V^2/Hz and not in V/sqrt(Hz)
since [ 9.2809nV/sqrt(Hz) ] ^2 = 8.61351e-17 V^2/Hz

Oliver

 

[oliver]

On Jun 27, 10:42 am, egolz...@gmail.com wrote:

i want to use hspice for plot output noise i write : .noise v(vout)
vin dec 10 100meg 3g
though I'm  somewhat in doubt as to how to interpret the results.
Basically the
 onoise_spectrum had about the shape  was about 8.613e-17  v/rt hz
whereas the data sheet listed something
 like  9.2809n v/rt hz noise (at the input).  What about this?

It seems the plotted output noise was in V^2/Hz and not in V/sqrt(Hz)
since [ 9.2809nV/sqrt(Hz) ] ^2 = 8.61351e-17 V^2/Hz

Oliver