Post subject: Error in ADS Posted: Tue May 02, 2006 5:05
Joined: Tue May 02, 2006 4:59 am
I use the Budget tool and got that error message :
[b]Error detected by HPEESOFSIM during Budget Analysis `Budget'.
Term3: ERROR: During Budget cascaded noise analysis; possible element
unrealistic S-parameters; look for |S11| > .8; |S22| >
.8; |S12| near, equal
or greater than |S21|. [/b]
anyone understand it ?
I know its depend on the attenuators location
but im not understand why .
subject: ADS error messagePosted: Tue May 02, 2006 6:32 pm
Joined: Wed Feb 22, 2006 3:51 pm
That's actually a more-helpful error message than
many, because it tells you what to look for in your design. Unfortunately
it's not very specific - it doesn't tell you where to look, and
it gives 3 alternatives.
The S11 and S22 checks say that
maybe there's a severe impedance mismatch between two stages, the
S12/S21 message says that maybe there's a large amount of (unexpected/undesired)
feedback around an active stage.
Post subject: Posted: Tue May 02, 2006 10:03 pm
Joined: Mon Jun 27, 2005 2:02 pm
I took the initiative
and replied to this post directly by email as we had already a brief
correspondence in the past. I mentioned that the main cause of such
a problem is instability (As fred47 mentioned), this is also noticed
by the values of S11, S22 which are greater than 1. This is likely
to be caused by poor matching. I also suggest you to do the budget
analysis simulation step by step from the start: Block after block.
And to see in which step the error message displays. By doing that
you can find out the problemtaic element and check it separately.