[ibis-macro] Re: Init Return Impulse models with Redriver
- From: <fangyi_rao@xxxxxxxxxxx>
- To: <scott@xxxxxxxxxxxxx>
- Date: Fri, 20 Jun 2014 17:43:53 +0000
Hi Scott,
Nonlinearity in redriver is modeled by redriver Rx GetWave and/or redriver Tx
GetWave. In Figs. 4 & 5 of the link below you can find some result of an AMI
redriver model with a limiting amplifier.
http://signal-integrity.tm.agilent.com/wp-content/uploads/2013/02/8-TA4_Paper_End-to-end_Link_Analysis.pdf
Fangyi
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx]
On Behalf Of Scott McMorrow
Sent: Friday, June 20, 2014 7:29 AM
To: RAO,FANGYI (A-USA,ex1)
Cc: D.Shah@xxxxxx; Walter Katz; IBIS-ATM
Subject: [ibis-macro] Re: Init Return Impulse models with Redriver
Fangyi
For a redriver, how is non-linearity in the receiver/driver handled. To me the
simplest useful case would be a limiting amplifier.
Scott
Scott McMorrow
Teraspeed® Consulting - A XXXXXX company
16 Stormy Brook Rd
Falmouth, ME 04105
(401) 284-1827 Business
http://www.teraspeed.com
More to come ... soon.
On Fri, Mar 14, 2014 at 1:20 PM,
<fangyi_rao@xxxxxxxxxxx<mailto:fangyi_rao@xxxxxxxxxxx>> wrote:
Please keep in mind that if one of the redriver Rx and Tx has GetWave, then the
entire impulse of the 1st channel must be removed from the final impulse by
deconvolution, which is known to be unreliable for long impulses. Not to
mention the complexities associated with cascaded repeaters and with crosstalk.
Regards,
Fangyi
From: ibis-macro-bounce@xxxxxxxxxxxxx<mailto:ibis-macro-bounce@xxxxxxxxxxxxx>
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx<mailto:ibis-macro-bounce@xxxxxxxxxxxxx>]
On Behalf Of Darshan Shah
Sent: Friday, March 14, 2014 9:51 AM
To: Walter Katz; ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>
Subject: [ibis-macro] Re: Init Return Impulse models with Redriver
Sure, we can work on this.
-Darshan
From: Walter Katz [mailto:wkatz@xxxxxxxxxx]
Sent: Friday, March 14, 2014 7:07 AM
To: Darshan Shah; ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>
Subject: RE: [ibis-macro] Init Return Impulse models with Redriver
Darshan,
You are correct, the spec is broken for Redrivers. Would you like to work with
me on creating a BIRD that will correct this?
Walter
From: ibis-macro-bounce@xxxxxxxxxxxxx<mailto:ibis-macro-bounce@xxxxxxxxxxxxx>
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Darshan Shah
Sent: Thursday, March 13, 2014 6:50 PM
To: ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>
Subject: [ibis-macro] Init Return Impulse models with Redriver
Hi,
I have following setup for my simulation
TX AMI model (Init_Return_Impulse = True, Getwave = False) --> Upstream Channel
--> Repeater RX (redriver and not retimer) AMI model (Init_Return_Impulse =
True, Getwave = False) --> Repeater TX (redriver and not retimer) AMI model
(Init_Return_Impulse = True, Getwave = False) --> Downstream Channel --> RX AMI
model (Init_Return_Impulse = True, Getwave = False)
I have Init Return Impulse model for all the 4 serdes and no Getwave model.
Also, RX (not repeater RX but RX at extreme right) has feature of auto tuning.
Looking into all the 9 steps of Repeater simulation (Page 224 of ver6_0.pdf),
it looks like there is no effect on RX Auto Adaptation algorithm due to
upstream channel.
The way it works is Upstream channel IR is calculated (convolution of upstream
channel + TX serdes + Repeater RX serdes IR) which is upto step 3 of spec. and
then Downstream Channel IR is calculated (convolution of downstream channel +
Repeater TX serdes + RX serdes IR) which is upto step 6 of spec.
It looks like RX serdes eq. parameters are auto tuned based on IR presented to
RX serdes input which is IR of (downstream channel + Repeater TX serdes) and
hence effect of upstream channel, TX serdes and Repeater RX serdes has no
impact on RX adaptation algorithm which is incorrect.
Please correct if I am wrong.
Any help will be really appreciated.
Thanks,
Darshan
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