Arpad, We have a published spec that says the analog model is to be included in the calculation of that channel impulse response. Anything else is not compliant. Todd. -- Todd Westerhoff VP, Software Products SiSoft 6 Clock Tower Place, Suite 250 Maynard, MA 01754 (978) 461-0449 x24 twesterh@xxxxxxxxxx www.sisoft.com “I want to live like that" -Sidewalk Prophets On Dec 12, 2012, at 4:21 PM, "Muranyi, Arpad" <Arpad_Muranyi@xxxxxxxxxx> wrote: > Todd, > > This is not super-theoretical-science in the clouds. > > It can be done just as practically and “easily” as the > EQ, DFE and CDR AMI algorithms can be done in the DLL-s. > It involves the same kind of algorithm knowledge, and > programming skill. > > The question is, do we want to let model makers to do > this, and possibly get a bunch of bad models from > inexperienced people, or should we, the EDA vendors > still have the opportunity to sell our expertise and > provide higher quality and more reliable solutions to > our customers and AMI model users. > > Thanks, > > Arpad > ========================================================== > > From: ibis-macro-bounce@xxxxxxxxxxxxx > [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Todd Westerhoff > Sent: Wednesday, December 12, 2012 2:54 PM > To: Dmitriev-Zdorov, Vladimir; 'Gregory R Edlund' > Cc: ibis-macro@xxxxxxxxxxxxx > Subject: [ibis-macro] Re: Analog Buffer Model Inside DLL > > Vladimir, > > Not clear to me how you propose to handle the reflections associated with > discontinuities at the point where the TX and RX analog circuits interface to > the channel. More importantly, even if it’s theoretically possible, that > doesn’t make it practical. > > I’ll admit I’m guessing here, but I expect Greg wants to solve a problem, not > just establish that it should be possible to solve it. > > Todd. > > > Todd Westerhoff > VP, Software Products > Signal Integrity Software Inc. • www.sisoft.com > 6 Clock Tower Place • Suite 250 • Maynard, MA 01754 > (978) 461-0449 x24 • twesterh@xxxxxxxxxx > > “I want to live like that” > -Sidewalk Prophets > > From: Dmitriev-Zdorov, Vladimir [mailto:vladimir_dmitriev-zdorov@xxxxxxxxxx] > Sent: Wednesday, December 12, 2012 2:39 PM > To: twesterh@xxxxxxxxxx; 'Gregory R Edlund' > Cc: ibis-macro@xxxxxxxxxxxxx > Subject: RE: [ibis-macro] Re: Analog Buffer Model Inside DLL > > In an abstract/theoretical way, it is still possible that AMI DLL correctly > takes care of the “impulse response” by adding its internal model to it. Then > however it should not be an ‘impulse response’, but 2- or 4-port S-parameters > representing the core portion of the channel, which does not include analog > models. Each model then can ‘append’ its analog part to the S-parameters, and > restore the resulting impulse response, if needed for equalization. Instead > of returning the updated impulse response, the Init function (or how we call > it) will return the updated touchstone file, which then is passed to the Rx > model, with the same purpose. > > The objection here is that Tx must have the complete channel info, with Rx > analog model, before its Init function can start thinking about > equalization, but then ‘appending’ analog models could be either separated > from Init, and organized as one more function, possibly combined with what > Fangyi proposed about resolving dependences, or we could still do everything > in just one function, but perform a few cycles of Initialization, for > example: (Tx_Init(), Rx_Init()), (Tx_Init(), Rx_Init()) … which resembles > “backchannel” communication on Init() stage. > > Of course, the writer of the AMI model must be able to do some operations > with touchstone files, such as appending the model to it, and converting it > into transfer function, finding impulse response by IFFT, etc. > > From: ibis-macro-bounce@xxxxxxxxxxxxx > [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Todd Westerhoff > Sent: Wednesday, December 12, 2012 11:51 AM > To: 'Gregory R Edlund' > Cc: ibis-macro@xxxxxxxxxxxxx > Subject: [ibis-macro] Re: Analog Buffer Model Inside DLL > > Greg, > > Ask yourself how the person writing an algorithmic model should accurately > model the reflections associated with an unspecified channel. If there’s a > way to do that, I’d like to hear about it. > > Todd. > > > Todd Westerhoff > VP, Software Products > Signal Integrity Software Inc. • www.sisoft.com > 6 Clock Tower Place • Suite 250 • Maynard, MA 01754 > (978) 461-0449 x24 • twesterh@xxxxxxxxxx > > “I want to live like that” > -Sidewalk Prophets > > From: Gregory R Edlund [mailto:gedlund@xxxxxxxxxx] > Sent: Wednesday, December 12, 2012 1:41 PM > To: Todd Westerhoff > Cc: ibis-macro@xxxxxxxxxxxxx > Subject: Re: [ibis-macro] Analog Buffer Model Inside DLL > > Todd, > > Thanks for the response. > > So, there are no "mathematical tricks" one can play in the DLL to account for > the absence of the analog buffer model in the impulse response? You can tell > I haven't taken enough time to think this through all the way. I'm having a > knee-jerk reaction to a discussion that's going on internally. 8-) I'm > about to dig into the IBIS 5.1 flow material to support my position. I just > wanted to make sure I had my ducks in a row and get some outside > corroboration. > > Anyone else care to chime in? > > Greg Edlund > Senior Engineer > Signal Integrity and System Timing > IBM Systems & Technology Group > 3605 Hwy. 52 N Bldg 050-3 > Rochester, MN 55901 > > > > <image001.gif>Todd Westerhoff ---12/12/2012 12:31:11 PM---Greg, That is not > possible. The analog model, by definition, interacts with the channel and > must be > > From: Todd Westerhoff <twesterh@xxxxxxxxxx> > To: Gregory R Edlund/Rochester/IBM@IBMUS > Cc: "ibis-macro@xxxxxxxxxxxxx" <ibis-macro@xxxxxxxxxxxxx> > Date: 12/12/2012 12:31 PM > Subject: Re: [ibis-macro] Analog Buffer Model Inside DLL > > > > > Greg, > > That is not possible. The analog model, by definition, interacts with the > channel and must be included in the impulse response. The equalization, also > by definition, is considered to be electrically isolated from the channel and > is thus represented in the DLL. > > Putting the analog model in the DLL violates a fundamental assumption of > IBIS-AMI. You may get good-looking results, but they will be invalid. > > Todd. > > > -- > > Todd Westerhoff > VP, Software Products > SiSoft > 6 Clock Tower Place, Suite 250 > Maynard, MA 01754 > (978) 461-0449 x24 > twesterh@xxxxxxxxxx > www.sisoft.com > > > “I want to live like that" > -Sidewalk Prophets > > > On Dec 12, 2012, at 1:13 PM, Gregory R Edlund <gedlund@xxxxxxxxxx> wrote: > > What nasty things are likely to happen if someone puts the analog buffer > model inside the DLL? At the very least, the impulse response will be > incorrect. > > Are there any circumstances under which this can work correctly? > > Greg Edlund > Senior Engineer > Signal Integrity and System Timing > IBM Systems & Technology Group > 3605 Hwy. 52 N Bldg 050-3 > Rochester, MN 55901