[SI-LIST] Re: hspice questions
- From: mwilbur@xxxxxxxxxxxx
- To: "Jim (James) Antonellis" <janton@xxxxxxxxxxxx>
- Date: Wed, 19 Mar 2008 11:23:57 -0400
To find crossing time of a differential signal, use a vcvs to make a new signal
consisting of vp - vn. The time that signal crosses zero is the time the two
diff'l signals cross.
Quoting "Jim (James) Antonellis" <janton@xxxxxxxxxxxx>:
>
> Hi Siva,
>
> Many ways to "skin the cat", here are a couple:
>
> If you have Cscope with your HSPICE (CosmosScope is a waveform viewer
> also a Synopsys product) you can easily plot Eye Diagrams and measure
> the zero-crossing of all transitions. Avanwaves is an older Synopsys
> waveform viewer that can alos plot Eye diagrams and give you the zero
> crossing measurement.
>
> In regards to "sweeping" multiple parameters, Using the ".Data" and
> ".ALTER"
> HSPICE constructs you can get any nested loop parameter sweep you
> desire!
>
> For example (this is only psuedo code from memory):
>
> .tran STEP END sweep =3D foobar
>
> .DATA foobar
> param1 param2
> x y
> m n
> a b
> .ENDDATA
>
> .ALTER
> .del lib SLOW_PVT
> .lib FAST_PVT
>
>
> This example will produce 6 runs. The inner loop (.DATA) provides 3
> sweeps=20
> of param1 and param2. The outer loop (.ALTER) will add a second run with
> a change in my process lib.
>
>
>
>
> Jim Antonellis=20
>
> janton@xxxxxxxxxxxx
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> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Siva kumar
> Sent: Tuesday, March 18, 2008 11:50 AM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] hspice questions
>
> ladies and gentlemen,
> i am a newbie to Hspice and i have few questions on it.
>
> 1. I have a differential clock output and i would like to measure the
> signal crossing points (the time at which the clk_p and clk_n crossing
> event occurs.). I went thru the user manuals and tutorials. Though there
> are bunch of info on .MEASURE command, but i couldnt find a method to
> find the crossing of clk_p and clk_n.
> these values i need it to do the timing analysis.
>
> 2. My signals operates at 400mbps and i would like to generate the eye
> diagram. how to do that using hspice.
> can anybody give info on that?
>
> 3. I have one more question on Paramater sweep. I need to sweep two
> variables in my circuit.=20
>
> For example,
>
> .tran 0.01ns 20ns sweep length1 100 1000 100 .tran 0.01ns 20ns sweep
> length2 500 1000 250
>
> i tried like above but always i am seeing only one variable in the
> waveform.( if i sweep var1 and var2 using the above method, tr1 and tr2
> results with var1 displayed but i dont know for which value of var2 the
> sweep happened..
>
> The objective is, i am doing the SI analysis and i want to sweep the
> tracelengths of the topology.
>
> I want to try like the following for loop and print both length1 and
> length2.=20
>
> for length1=3D100 to 1000 step 100
> {
> for length2=3D500 to 1000 step 25
> }
>
> thanking you in advance.
>
> Also i would appreciate if anybody can share any advanced / complex
> examples on SI analysis using hspice that helps to improve the
> efficiency and saves time.
>
> thanks,
> kumar
>
>
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