[ibis-macro] Re: Jitter BIRD issues, and Buffer Tstonefile Issues

  • From: "Ken Willis" <kwillis@xxxxxxxxxxx>
  • To: <vladimir_dmitriev-zdorov@xxxxxxxxxx>, "'Walter Katz'" <wkatz@xxxxxxxxxx>, <fangyi_rao@xxxxxxxxxxx>, <ibis-macro@xxxxxxxxxxxxx>
  • Date: Fri, 9 Dec 2011 11:40:11 -0500

Hi Vladimir,

 

I think we need to be careful on your item #2:

 

Our convention is that 'statistical' analysis means simulation without
GetWave calls, while time domain simulation is a relatively long analysis
with multiple GetWave calls.

 

There is no reason why you can't perform time domain simulation where both
Tx and Rx AMI models are init-based, and don't use GetWave, correct? In that
case the user has a choice to do either statistical analysis or time domain
simulation. We shouldn't make the general association that AMI_Init =
statistical and AMI_GetWave = time domain.

 

Thanks,

 

Ken Willis

Sigrity, Inc.

860-871-7070

kwillis@xxxxxxxxxxx

 

  _____  

From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Dmitriev-Zdorov,
Vladimir
Sent: Tuesday, December 06, 2011 5:20 PM
To: Walter Katz; fangyi_rao@xxxxxxxxxxx; ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: Jitter BIRD issues, and Buffer Tstonefile Issues

 

Walter,

 

OK, that's sounds correct.

 

Vladimir

 

From: Walter Katz [mailto:wkatz@xxxxxxxxxx] 
Sent: Tuesday, December 06, 2011 3:14 PM
To: Dmitriev-Zdorov, Vladimir; fangyi_rao@xxxxxxxxxxx;
ibis-macro@xxxxxxxxxxxxx
Subject: RE: [ibis-macro] Re: Jitter BIRD issues, and Buffer Tstonefile
Issues

 

Vladimir,

 

I generally agree with your points 1 and 2.

 

3.2 is incorrect:

In Statistical, only Rx_Clock_PDF, Rx_Clock_Recovery_Rj,
Rx_Clock_Recovery_DCD, and Rx_Clock_Recovery_Sj are applied.

I believe I said that in statistical Rx_Clock_PDF, Rx_Clock_Recovery_Rj,
Rx_Clock_Recovery_DCD, Rx_Clock_Recovery_Sj, Rx_Rj, Rx_Sj and Rx_DCD are
applied.

 

1.       The current BIRD 123 states that Rx_Rj, Rx_DCD, and Rx_Sj shall be
applied to both Time Domain and Statistical methods.

a.       In Time Domain, Rx_Rj, Rx_DCD, and Rx_Sj can be applied to times in
clock_times, statistically to the clock_times PDF, or statistically to the
persistent eye.

b.       In Statistical, Rx_Rj, Rx_DCD, and Rx_Sj are combined statistically
along with Rx_Clock_PDF, Rx_Clock_Recovery_Rj, Rx_Clock_Recovery_DCD, and
Rx_Clock_Recovery_Sj.

 

Walter

 

From: Dmitriev-Zdorov, Vladimir [mailto:vladimir_dmitriev-zdorov@xxxxxxxxxx]

Sent: Tuesday, December 06, 2011 5:08 PM
To: wkatz@xxxxxxxxxx; fangyi_rao@xxxxxxxxxxx; ibis-macro@xxxxxxxxxxxxx
Subject: RE: [ibis-macro] Re: Jitter BIRD issues, and Buffer Tstonefile
Issues

 

 

 

From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx]
<mailto:%5bmailto:ibis-macro-bounce@xxxxxxxxxxxxx%5d>  On Behalf Of Walter
Katz
Sent: Thursday, December 01, 2011 8:05 PM
To: fangyi_rao@xxxxxxxxxxx; ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: Jitter BIRD issues, and Buffer Tstonefile Issues

 

Fangyi,

 

 

Walter,

 

I generally support your jitter proposal. We maybe we should add some
explanations to the usage of these parameters.

 

1.       Possible redundancy was mentioned today, because practically the
effect from Rx clock jitter and Rx CDR jitter could be summed up by EDA tool
or Rx model and represented in either Rx or Clock Recovery groups, or even
produced by the output clocks from GW model. I agree however that it makes
sense to list these parameters separately, to simplify their handling and
understanding by user. It is not difficult for EDA tool to collect the
effects from different jitter parameters together if needed.

2.        We need to avoid possible confusion when using the words
'statistical' and 'time domain' methods. Our convention is that
'statistical' analysis means simulation without GetWave calls, while time
domain simulation is a relatively long analysis with multiple GetWave calls.
With respect to Rx_XX and Rx_Clock_Recovery_XX groups, there is an
additional choice for EDA platform in time domain flow, to apply either
straightforward time domain implementation of such jitter, for example, by
calling the rand() functions, once every bit, or by accounting for the same
amount of jitter statistically, on the post processing stage (after time
domain simulation is completed). The choice should be up to EDA tool, since
both approaches have their advantages and limitations. In other words, in
statistical flow, all jitter parameters are applied statistically, but in
time domain flow, some could be applied in time domain and some
statistically (if possible).

3.       It's not quite clear for me the following from your previous email:

 

                       It has been suggested that Rx_Rj, Rx_DCD, and Rx_Sj
shall apply to just Time Domain.

1.      In Time Domain, Rx_Rj, Rx_DCD, and Rx_Sj can be applied to times in
clock_times, statistically to the clock_times PDF, or statistically to the
persistent eye.

2.      In Statistical, only Rx_Clock_PDF, Rx_Clock_Recovery_Rj,
Rx_Clock_Recovery_DCD, and Rx_Clock_Recovery_Sj are applied.

 

We understand Rx_Clock_Recovery_XX parameters are substitute for clock ticks
that we can use either in statistical flow or in time domain when clocks are
not returned. It seems logical to have Rx_XX type parameters for statistical
flow, too, since they correspond to a different source of jitter. This is
what the existing spec says. What is a motivation for this change?

Vladimir

 

 

 

 

 

From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx]
<mailto:%5bmailto:ibis-macro-bounce@xxxxxxxxxxxxx%5d>  On Behalf Of Walter
Katz
Sent: Tuesday, November 29, 2011 2:31 PM
To: IBIS-ATM
Subject: [ibis-macro] Jitter BIRD issues, and Buffer Tstonefile Issues

 

All,

 

The remaining major issue is the handling of Rx_Rj, Rx_DCD, and Rx_Sj.

1.       It has been requested that Rx_Dj be added.

2.       First a discussion on how the Rx clock is handled in the following
two cases

a.       Time Domain

                                                               i.      Rx
AMI_GetWave returns clock ticks in *clock_times.

b.       Statistical

                                                               i.      Rx
AMI_GetWave does not return clock ticks in *clock_times.

                                                             ii.      Using
Rx AMI_Init

3.       The current BIRD 123 states that Rx_Rj, Rx_DCD, and Rx_Sj shall be
applied to both Time Domain and Statistical methods.

a.       In Time Domain, Rx_Rj, Rx_DCD, and Rx_Sj can be applied to times in
clock_times, statistically to the clock_times PDF, or statistically to the
persistent eye.

b.       In Statistical, Rx_Rj, Rx_DCD, and Rx_Sj are combined statistically
along with Rx_Clock_PDF, Rx_Clock_Recovery_Rj, Rx_Clock_Recovery_DCD, and
Rx_Clock_Recovery_Sj.

4.       It has been suggested that Rx_Rj, Rx_DCD, and Rx_Sj shall apply to
just Time Domain.

a.       In Time Domain, Rx_Rj, Rx_DCD, and Rx_Sj can be applied to times in
clock_times, statistically to the clock_times PDF, or statistically to the
persistent eye.

b.       In Statistical, only Rx_Clock_PDF, Rx_Clock_Recovery_Rj,
Rx_Clock_Recovery_DCD, and Rx_Clock_Recovery_Sj are applied.

 

Regarding Tstonefile.

1.       Fangyi and I agreed the there is no requirement that S12=S21, and
that S21 can be small or zero.

2.       Fangyi and I agreed that the input to the Tx, and the output of the
Rx S element be isolated with a unit gain amplifier (E element) as in the
following example of a Tx Tstonefile wrapped in an ISS subckt:

a.    .subckt Intrinsic_Tstonefile_Tx DieP PadP DieN PadN file='NA'

b.    * Port order of Touchstone file is DieP PadP DieN PadN

c.    E_H EDieP 0 VCVS DieP 0 1.

d.    E_L EdieM 0 VCVS DieN 0 1.

e.    S1 EDieP PadP EDieN PadN 0 mname=A 

f.    .model A TSTONEFILE=file 

g.    .ends Intrinsic_Tstonefile_Tx

3.       There are now three proposals to implement Tstonefile in .ibs
and/or .ami files.

a.       BIRD 120 proposes the following example, where  (Voh-Vol) = Peak to
Peak voltage swing:

 
i.      (Tstonefile (List "xwc.s4p" "wc.s4p" "nc.s4p" "bc.s4p" "xwc.s4p") 

 
ii.      (Usage Info) (Type String) 

 
iii.      (Description "Extreme Worst, Worst, Nominal, Best, Extreme Best"))

 
iv.      (Vol  (Value 0.) (Usage Info)(Type Float))

 
v.      (Voh (Range 1 .3 1.2) (Usage Info)(Type Float))

b.       There are a number of BIRDs submitted by Arpad and Ambrish. I have
requested that the above example be implemented using the syntax proposed in
these alternative BIRDs.

 

Walter

 

 

Walter Katz

wkatz@xxxxxxxxxx

Phone 303.449-2308

Mobile 720.333-1107

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