[SI-LIST] Re: Simulating frequency dependent s-parameters in HSPICE
- From: Krishna Chaitanya <krishna1abc@xxxxxxxxx>
- To: Ray Anderson <ray.anderson@xxxxxxxxxx>
- Date: Mon, 12 Mar 2012 15:41:09 -0700
Ray, Thank you very much for explaining it.
Can I say that when I provide s-parameters for HSPICE simulation, the
results do take into account the frequency dependent parasitics (RLGC as
s-parameters)?
I use Q3D extractor for s-parameter extraction. In Q3D extractor if I
provide a sampling frequency of 1GHz and range from 1G to 30G with step
size of 1G, does it mean the frequency effects till 30G are being
considered in my simulations?
On what factors should I determine my sampling frequency, frequency range
and step size for extracting s-parameters?
Thanks,
Krishna
On Mon, Mar 12, 2012 at 3:20 PM, Ray Anderson <ray.anderson@xxxxxxxxxx>wrote:
> Krishna-
>
> The s-parameters you are using in your simulation ARE frequency
> dependent.
>
> The following is a small sample from a random Touchstone format
> s-parameter file. Each line contains the scattering parameters ( in this
> case, for a 2-port in Real/Imaginary format) for a specific sampled
> frequency:
>
> # KHz S RI R 50.00
>
> 3.00E+01 4.19E-01 -4.67E-01 5.81E-01 4.68E-01 5.81E-01 4.68E-01
> 4.19E-01 -4.67E-01
> 3.19E+01 3.91E-01 -4.62E-01 6.09E-01 4.62E-01 6.09E-01 4.62E-01
> 3.91E-01 -4.62E-01
> 3.39E+01 3.63E-01 -4.55E-01 6.37E-01 4.55E-01 6.37E-01 4.55E-01
> 3.63E-01 -4.55E-01
> 3.60E+01 3.37E-01 -4.47E-01 6.63E-01 4.47E-01 6.63E-01 4.47E-01
> 3.37E-01 -4.47E-01
>
> The s-parameters could be converted to a lumped RLGC representation, but
> for simulation in Hspice using the S-element that is NOT required (or
> desired). Note that each line describes the 2-port s-parameters (S11,
> S12, S21, S22 at a specific frequency). If necessary, the simulator can
> interpolate between the frequencies in the Touchstone file.
>
> When Hspice executes a time domain simulation as you have described it
> will perform a convolution of the driving signal with the s-parameters
> (in very simplistic terms) to arrive at the solution. It does not need
> to determine RLGC values at a specific datarate.
>
> -Ray Anderson
> Xilinx Inc.
>
>
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Krishna Chaitanya
> Sent: Monday, March 12, 2012 2:42 PM
> To: Ihsan Erdin; Sinha, Snehamay
> Cc: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Simulating frequency dependent s-parameters in
> HSPICE
>
> Hi Snehamay, Ihsan and others,
> Thank you very much for the SPICE syntax. I used that for the
> simulations
> but not clear how it guarantee frequency dependent RLGC are taken into
> account.
> When I give a PRBS input corresponding to a bit rate of say 2GBPS (or 1
> GHz
> of clk), does it mean the HSPICE will pick the RLGC values corresponding
> to
> this particular frequency of 1GHz?
> I do not see any visible connection which tells the SPICE to pick the
> RLGC
> values corresponding to the input data rate.
> Can you please help me understand what is happening when I simulate
> using
> s-parameters in HSPICE
>
>
> On Mon, Mar 12, 2012 at 9:55 AM, Krishna Chaitanya
> <krishna1abc@xxxxxxxxx>wrote:
>
> > Thanks all. I have few questions.
> >
> > I did try using s-element and I am not clear how to interpret my
> > simulation results.
> > For a simple case of inverter based driver and receiver,
> >
> > INV (driver) -> Through Silicon Via (Interconnect) -> Inv (Receiver)
> >
> > I have the s-parameter touchstone file for a range of frequencies for
> TSV
> > extracted using Q3D extractor. I simulated this in HSPICE using
> s-element
> > and I got some eye diagram for a PRBS pattern for a particular input
> data
> > rate.
> >
> > From my understanding, the R and L values atleast change with
> frequency
> > and depending on that my eye opening should change.
> > If I use the s-element method, I get a single eye diagram. How should
> I
> > interpret it?
> > Does it mean the eye diagram which I get after simulating using
> s-element
> > includes the effect of all the frequencies on RLGC parasitics?
> >
> > In short I am not clear how s-element simulations guarantee that my
> > simulation results include frequency dependent RLGC parasitics.
> >
> > Thanks,
> > krishna
> >
> >
> > On Mon, Mar 12, 2012 at 9:29 AM, Ihsan Erdin <erdinih@xxxxxxxxx>
> wrote:
> >
> >> Krishna,
> >>
> >> In hspice, you can directly plug in those s-parameters to your
> netlist as
> >> an s-element. As there's no need for a w-element using one wouldn't
> be
> >> right either. You can model the rest of the tracks with the
> w-element.
> >> Below, I suspect you're referring to a totally different case which
> is
> >> about assigning freq. dependent PUL parameters to the w-element from
> a
> >> touchstone file. This can only be be used when the track parameters
> are
> >> computed with a third party tool and completely irrelevant to what
> you're
> >> trying to accomplish in this particular situation -if I understood
> your
> >> case correctly, of course...
> >>
> >> Regards,
> >>
> >> Ihsan
> >>
> >> On Mon, Mar 12, 2012 at 11:28 AM, Krishna Chaitanya <
> >> krishna1abc@xxxxxxxxx> wrote:
> >>
> >>> Hello All,
> >>> I am trying to analyze the impact of frequency dependent parasitics
> of
> >>> Through Silicon Vias on data rate. I used Ansoft Q3D extract to
> obtain
> >>> RLGC
> >>> parasitics as s-parameter Touchstone file for a range of
> frequencies.
> >>> Now I
> >>> would like to know how can I use this file in HSPICE simulation.
> When I
> >>> use
> >>> w-element method in HSPICE it can take touchstone file as input but
> I am
> >>> not sure whether it is the correct way to simulate any frequency
> >>> dependent
> >>> parasitics in HSPICE.
> >>>
> >>> Any help?
> >>>
> >>> Thanks,
> >>> Krishna
> >>>
>
>
>
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