[ibis-serdes-backchan] Structural changes to the AMI standard required to support Backchannle Co-optimization
- From: "Walter Katz" <wkatz@xxxxxxxxxx>
- To: "'IBIS-ATM'" <ibis-macro@xxxxxxxxxxxxx>
- Date: Fri, 11 Feb 2011 09:00:05 -0500
IBIS-ATM,
This e-mail is being sent to the IBIS ATM (Advanced Technology Modeling)
group to describe the structural changes required to the IBIS-AMI interface.
The Backchannel Reflector is being cc's as well.
Two changes are required to the IBIS-AMI interface to support backchannel.
The first is to allow the Tx AMI DLL to know what the Rx AMI DLL is telling
it and the Rx AMI DLL needs to know what the Tx AMI DLL is telling it.
Information is currently passed into a DLL as a text string in in a similar
parameter tree format as defined in the .ami file for that model. The roor
of this parameter tree is the root of the parameter tree in the .ami file.
The simple enhancement to the AMI interface is to allow this string to
contain two parameter trees, one with the root of the parameter tree for the
model, and the other tree containing the root of the parameter tree fo the
model at the other end of the channel. The following example should make
this clearer:
Assume that the parameter tree for the Tx model is:
(Tx_Root (FFE_Tap (-1 -.03) (0 .9) (1 -.07)))
and the parameter tree for the Rx model is:
(Rx_Root (DFE_Tap (1 -.1) (2 -.05) (3 .05) (4 .1) (5 -.01)))
In the current standard the Tx just gets the (Tx_Root .) tree and the Rx
just gets the (Rx_Root .) tree.
The proposed change will allow the Tx model to receive:
(Tx_Root (FFE_Tap (-1 -.03) (0 .9) (1 -.07))) (Rx_Root (DFE_Tap (1 -.1) (2
-.05) (3 .05) (4 .1) (5 -.01)))
and the Rx model to receive
(Rx_Root (DFE_Tap (1 -.1) (2 -.05) (3 .05) (4 .1) (5 -.01))) (Tx_Root
(FFE_Tap (-1 -.03) (0 .9) (1 -.07)))
Thus, the Rx model can determine the number of Tx pre-cursor and post-cursor
taps, and the values of all of the Tx taps.
The DLL's not only receive data in this format, but also output data in this
same format. Thus the Rx model can output these same trees with updated
values of the Tx Taps.
As described in previous e-mails, there are three entry points to an AMI
model, AMI_Init, AMI_GetWave, and AMI_Close. The AMI_Init entry has a
parameters_in pointer and a parameters_out pointer. The AMI_GetWave entry
only has a parameters_out pointer. Since Backchannel will require the
ability to pass a parameter tree inot the AMI_GetWave entry, the AMI
interface standard needs to modified to allow the AMI_GetWave parameters_out
pointer to also serve as a pointer to an input string.
To enable the above changes, we will need to define a new Reserved Parameter
to indicate that this DLL does support multiple parameter trees in the input
parameter tree, and that the AMI_GetWave support the parameter_out pointer
use as an input as well as an output.
Walter
Walter Katz
Chief Scientist
Signal Integrity Software, Inc.
wkatz@xxxxxxxxxx
303.449-2308
Other related posts:
- » [ibis-serdes-backchan] Structural changes to the AMI standard required to support Backchannle Co-optimization - Walter Katz
