[ibis-macro] Re: Init Return Impulse models with Redriver
- From: Darshan Shah <D.Shah@xxxxxx>
- To: "ambrishv@xxxxxxxxxxx" <ambrishv@xxxxxxxxxxx>, "ibis-macro@xxxxxxxxxxxxx" <ibis-macro@xxxxxxxxxxxxx>
- Date: Fri, 14 Mar 2014 18:01:57 +0000
Hi Ambrish,
But this can be resolved inside EDA tool to get proper results.
-Darshan
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx]
On Behalf Of Ambrish Varma
Sent: Thursday, March 13, 2014 9:50 PM
To: ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: Init Return Impulse models with Redriver
Hi Darshan,
The analysis appears to be correct and demonstrates a limitation of Init Only
models.
Thanks,
Ambrish.
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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