The Designer's Guide Community
Forum
Welcome, Guest. Please Login or Register. Please follow the Forum guidelines.
Sep 17th, 2019, 3:42pm
Pages: 1
Send Topic Print
z transform filter in ac (Read 5287 times)
roberto_d
New Member
*
Offline



Posts: 2
Switzerland
z transform filter in ac
Feb 22nd, 2011, 5:14am
 
Hello,

I'm trying to implement some z transform filters in Verilog-A (to be simulated with Spectre).
I did a very simple sample and hold (transfer function =1 in z domain):
Quote:
`include "constants.vams"
`include "disciplines.vams"

module sh(MINUS, PLUS);
  inout MINUS;
 electrical MINUS;
 inout PLUS;
 electrical PLUS;
 analog begin
   V(MINUS)<+zi_nd(V(PLUS),{1},{1},2u,2n);
   end
endmodule


This work perfectly fine in the time domain, but shouldn't I also see the effect of s/h in ac analysis? In fact, what I see in ac is vout=vin
Thanks
Roberto
Back to top
 
 
View Profile   IP Logged
August West
Community Member
***
Offline

I'll get up and fly
away

Posts: 71

Re: z transform filter in ac
Reply #1 - Feb 23rd, 2011, 1:01am
 
Yes, of course. However, if you carefully look at the log file you will probably find a warning that says that the z-filter is not implemented in AC analysis yet. That message has been there since 1994. I'm thinking this one is not a high priority for Cadence.

August
Back to top
 
 
View Profile   IP Logged
roberto_d
New Member
*
Offline



Posts: 2
Switzerland
Re: z transform filter in ac
Reply #2 - Feb 23rd, 2011, 9:30am
 
I see... It would have been too nice...
But since 94 they made a BIG step forward, now they don't even show a warning in the log file!
Ok thanks, at least I can stop asking myself what I did wrong.
Back to top
 
 
View Profile   IP Logged
August West
Community Member
***
Offline

I'll get up and fly
away

Posts: 71

Re: z transform filter in ac
Reply #3 - Feb 24th, 2011, 11:30pm
 
If you don't see the warning message, then you might want to inquire with Cadence. After all, it has been a 16 years. Perhaps they did get around to fixing it, or at least trying to. After all, why would they take out the warning if they didn't try to fix it?

And, besides, if they did not fix it, they should at least be made aware from time to time that people care.

-August
Back to top
 
 
View Profile   IP Logged
Pages: 1
Send Topic Print
Copyright 2002-2019 Designer’s Guide Consulting, Inc. Designer’s Guide® is a registered trademark of Designer’s Guide Consulting, Inc. All rights reserved. Send comments or questions to editor@designers-guide.org. Consider submitting a paper or model.