Hi All,
I am new to this forum and also to Verilog-AMS.
I would like to use some testbenches made of varilog-ams blocks for AC analysis especially for testing stability and bandwidth.
Can someone tell me if this is possible? If yes how is possible if every blocks is made of code insted of R and C? Who generates the poles and the zeros?
Many thanks

Geoffrey_Coram wrote on Mar 16^th, 2009, 5:33am:


sorry for continue discussing about this thread.
i want to make AC analysis bellow case w/t verilog-HDL and Verilog-AMS.

　　input analog V(Vin) => AD comparator(verilog-AMS)
　　　=> LOGIC(verilog-HDL)
　　　=> DA comparator(verilog-AMS) => output analog V(Vout)

I want to make AC analysis btw Vin and Vout.
this case, should be use both logic and spice simulator.

plz let me know how to use function or tool for AC analysis.

I'm waiting for your advice
See you soon again
ciao

Dear Boe!!
at first, I apologize my much late response ( 1 week )...

boe wrote on Oct 30^th, 2009, 11:37am:

　
ohps!! I fully(?) understand your mentioned. that's right.
Sorry for my easy idea for asking AC analysis w/t Logic function.
　
　but in future, we should solve this item. 　
　
　how about your opinion?
　Is there no way only w/t 3,4 your mentioned case ?
　maybe these points are the most important points.....
　
How to treat digital filter behavior depend on frq on AC analysis.
　
i want to solve .... not now but future. is it far from now?
　
　

boe wrote on Oct 30^th, 2009, 11:37am:
Not correct.

boe wrote on Nov 2^nd, 2009, 3:58am:
You can not adopt PSS/PAC of Cadence Spectre to behavioral model simulation of Digital Filter or SCF using Verilog-A generally since there are hidden states.
http://www.designers-guide.org/Forum/YaBB.pl?num=1210932698/1#1

boe wrote on Nov 2^nd, 2009, 3:58am:
MATLAB is different from Simulink.

sand_dolphin2 wrote on Oct 26^th, 2009, 4:30pm:
Use cosimulation between spice type transient simulator and logic simulator.
http://www.designers-guide.org/Forum/YaBB.pl?num=1238242506/1#1

Here driving Vin by sinusoidal signal with varying frequency, you can evaluate frequency characteristics between Vin and Vout.

sand_dolphin2 wrote on Nov 4^th, 2009, 4:12pm:
What procedure do you take and what instruments do you use in actual evaluation ?
Consider actual situation of evaluation.
Show me your realization method of AC Analysis in actual evaluation.

Learn measurements using actual instruments. Not "EDA Tool Play".


sand_dolphin2 wrote on Nov 4^th, 2009, 4:12pm:
Do you understand AC Analysys correctly ?

If your intererst is limited to very narrow aspect of DUT, you might be able to use high abstract level modeling for DUT.
For example, if you can build "State Averaged Model" for target DUT, you can adopt conventional AC Analysis.

This "State Averaged Modeling" is well known as "Describing Function Method" or "Equivalent Transfer Function Method"
in Nonlinear Control Theory.

Equivalent Lowpass Model of RF Bandpass System is this "State Averaged Modeling".
Phase Domain Model of PLL is also this "State Averaged Modeling".

If you can know Z-domain Transfer function of Digital Filter or SCF, you can use conventional AC Analysis for evaluation of frequency characteristics of them.

What on earth do you expect for Verilog-AMS ?
Functional Verification ?
High Abstract Level Modeling of DUT with very narrow aspect ?


sand_dolphin2 wrote on Nov 4^th, 2009, 4:12pm:
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sand_dolphin2 wrote on Nov 8^th, 2009, 10:02pm:
Still your expression is wrong.
It has to be "Evaluation of Digital filter's Frequency Characteristics".

Generally you have to use Transient Analysis for "Evaluation of Digital filter's Frequency Characteristics".
Here frequency characteristics is evaluated by DFT of impulse response.
Again see http://www.designers-guide.org/Forum/YaBB.pl?num=1210932698/1#1

If you want to use AC analysis for "Evaluation of Digital filter's Frequency Characteristics",
you have to describe transfer function as Z-domain expression.
That's all.

Still if you can't understand,
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