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$rdist_xxx not supported outside the analog block in AMS Designer (Read 6205 times)

ywguo

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Posts: 943
Shanghai, PRC

$rdist_xxx not supported outside the analog block in AMS Designer
Oct 09^th, 2011, 1:52am

Hi Guys,

I have verilog-AMS code as below. I want to have random variation for cap15.
Code:

 � parameter real c15 = 5.12p from (0:inf);
 �real cap15, ....
 � initial begin
 � � cap15 = ($rdist_normal(1,0,1)*0.001*sqrt(2^10)+1)*c15;
 � end

However it stops in elaboration and reports
Quote:

� �Elaborating the design hierarchy:
ncelab: *N,SFEDPL: Deploying new SFE in analog engine.
�Discipline resolution Pass...
�Building instance overlay tables: ................
� cap15 = ($rdist_normal(1,0,1)*0.001*sqrt(2^10)+1)*c15;
|
ncelab: *E,EXNOSUP (./dac.vams,38|24): In AMS Designer, the shown system function is not supported outside the analog block.
.... Done
ncverilog: *E,ELBERR: Error during elaboration (status 1), exiting.

Unfortunately, AMS designer does not compatible with Verilog-AMS LRM version 2.3 fully. What can I do?

Thanks
Yawei

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boe Community Fellow Offline Posts: 615	Re: $rdist_xxx not supported outside the analog block in AMS Designer Reply #1 - Oct 10^th, 2011, 2:28am Hi Ywguo, I'd try the initial_step event. B O E
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Ken Kundert Global Moderator Offline Posts: 2384 Silicon Valley	Re: $rdist_xxx not supported outside the analog block in AMS Designer Reply #2 - Oct 10^th, 2011, 9:38am Try $dist_normal(). I think that is the name used in the digital context. -Ken
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boe Community Fellow Offline Posts: 615	Re: $rdist_xxx not supported outside the analog block in AMS Designer Reply #3 - Oct 10^th, 2011, 10:37am Hi, The documentation clearly states that $rdist_xxx is not supported in digital contexts. Quote: Try $dist_normal(). I think that is the name used in the digital context. However, according to the documentation nowadays it generates integers. B O E
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Geoffrey_Coram Senior Fellow Offline Posts: 1998 Massachusetts, USA	Re: $rdist_xxx not supported outside the analog block in AMS Designer Reply #4 - Nov 4^th, 2011, 5:24am Can't you re-scale the integers from $dist_normal (divide by the largest) and get something close to what you want?
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