[ibis-macro] Re: Init Return Impulse models with Redriver
- From: Walter Katz <wkatz@xxxxxxxxxx>
- To: <D.Shah@xxxxxx>, <ibis-macro@xxxxxxxxxxxxx>
- Date: Fri, 14 Mar 2014 10:06:34 -0400 (EDT)
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] On Behalf Of Darshan Shah
Sent: Thursday, March 13, 2014 6:50 PM
To: 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) à Upstream
Channel à Repeater RX (redriver and not retimer) AMI model
(Init_Return_Impulse = True, Getwave = False) à Repeater TX (redriver and
not retimer) AMI model (Init_Return_Impulse = True, Getwave = False) à
Downstream Channel à 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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