[SI-LIST] Re: IBIS-AMI linearity
- From: "Walter Katz" <wkatz@xxxxxxxxxx>
- To: <Arpad_Muranyi@xxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Tue, 19 Mar 2013 13:19:42 -0400 (EDT)
Arpad, Todd, Igal,
IBIS-AMI does assume LTI behavior of the channel which include the Tx and Rx
analog buffers. If, in fact, the Tx Pullup and Pulldown curves and Tx and Rx
Power and Ground Clamp curves are linear, then all is simple, and the
channel is truly LTI. If these IV curves are not linear, the EDA must
generate the impulse response of the channel carefully assuming LTI behavior
of these IV curves around the nominal operating point of the channel.
Walter
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Muranyi, Arpad
Sent: Tuesday, March 19, 2013 12:56 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: IBIS-AMI linearity
Todd, Igal,
To be a little more precise, the IBIS spec says that the channel, including
the analog portions of the Tx and Rx models has to be LTI. From pg. 122 of
the v5.1 IBIS specification:
Algorithmic modeling of advanced Serializer-Deserializer (SERDES) devices is
supported by IBIS, through the Algorithmic Modeling Interface (AMI). The AMI
approach breaks SERDES device modeling into two parts – electrical and
algorithmic. The combination of the transmitter’s analog back-end, the
serial channel and the receiver’s analog front-end are assumed to be linear
and time invariant. There is no limitation that the equalization has to be
linear and time invariant. The “analog” portion of the channel is
characterized by means of an impulse response leveraging the IBIS constructs
for device models defined in Sections 6, 6A and 6B.
Thanks,
Arpad
=======================================================
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Todd Westerhoff
Sent: Tuesday, March 19, 2013 11:47 AM
To: fridman igal
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: IBIS-AMI linearity
Igal,
The IBIS 5.1 spec says the TX output buffer (think of the analog driver that
connects directly to the channel) is treated as an LTI behavior. The
transmitter's equalization characteristic can be either LTI (AMI_Init,
impulse response processing) or non-LTI (AMI_Getwave, waveform processing).
The device is represented by the combination of the analog and algorithmic
models, which are processed sequentially.
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
----- Original Message -----
From: "igal_fr" <fridman.igal@xxxxxxxxx>
To: si-list@xxxxxxxxxxxxx
Sent: Tuesday, March 19, 2013 10:05:38 AM
Subject: [SI-LIST] IBIS-AMI linearity
Hello experts,
In SerDes channel analysis widely used convolution operator, which assumes
LTI properties of channel components, including TX and Rx.
I'm not sure if the SerDes Tx, modeled by IBIS-AMI method, can be treated as
linear.
Please advise.
Thank you,
Igal
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