Fangyi, I deleted the emails below after your first message to make it easier to see what you were referring to. I see what you mean now. We need to distinguish between the AMI flow and the legacy flow. Not only that, we also have to define the nature of the input and output of the Tx and Rx analog models. Our current specification leaves a lot of room for differences of opinion and arguments over that topic as we have experienced it not too long ago. What you are referring to below is the AMI flow. What I was referring to was the legacy flow. A question was raised in the emails after your original posting on what the analog models should do in a legacy simulation environment. Should they be cascaded as repeaters also? Several comments were made to that question. One was to ignore the fact that these analog buffer models are part of a repeater. My comment was that they could also be cascaded if we defined in the spec how that is done. I am trying to illustrate that in the attached PDF file. However, in addition to that, your AMI flow seems to assume that the the output of the Rx analog model and the input to the Tx analog model are analog. This needs to be defined, otherwise different people will have different assumptions and with the wrong assumptions one will not be able to implement your repeater proposal correctly. So I think your BIRD should define the following: 1) how are the analog models used in legacy simulations 2) how are the analog models used in the IBIS-AMI simulations for channel characterization 3) how are the analog models used in the AMI flow 4) what is the nature of the analog models in either of these flows Thanks, Arpad ======================================================================= From: fangyi_rao@xxxxxxxxxxx [mailto:fangyi_rao@xxxxxxxxxxx] Sent: Wednesday, March 13, 2013 12:59 PM To: Muranyi, Arpad; ibis-macro@xxxxxxxxxxxxx Subject: RE: [ibis-macro] Re: redriver in spice simulation Arpad; In a redriver, the Tx half is driven by the Rx half’s output signal and retransmits it to the downstream channel. Fangyi From: fangyi_rao@xxxxxxxxxxx<mailto:fangyi_rao@xxxxxxxxxxx> [mailto:fangyi_rao@xxxxxxxxxxx] Sent: Tuesday, March 12, 2013 4:58 PM To: Ambrish Varma; ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx> Subject: redriver in spice simulation Hi, Ambrish; I am not sure if your suggestion of shorting redriver Rx ibis output pin to the redriver Tx ibis input pin in spice simulations will work because in spice simulations 1. legacy Tx ibis model is driven by input signal threshold crossing events. That’s not how a redriver Tx half is driven by input signal. 2. legacy Rx ibis model output is a digital signal of 1’s and 0’s (hopefully I am correct here). That’s not what redriver Rx half outputs. Due to the uncertainties in redriver model behavior in non-AMI simulations, I prefer to keep my redriver BIRD separate from Walter’s repeater BIRD, at least for now. Regards, Fangyi
Attachment:
RepeaterFlow.pdf
Description: RepeaterFlow.pdf
