[ibis-macro] Re: FW: [IBIS-Users] AMI convolution
- From: "Mellitz, Richard" <richard.mellitz@xxxxxxxxx>
- To: Scott McMorrow <scott@xxxxxxxxxxxxx>, "msteinb@xxxxxxxxxx" <msteinb@xxxxxxxxxx>
- Date: Mon, 23 Nov 2009 08:10:57 -0700
Let's take this one step at a time. Let's start with port loss. I don't want to
mix metaphors by going directly modal issue yet. I may be missing something in
IBIS-AMI so help me understand this "baby step".
It look to me like we are taking about the voltage transfer function (VTF).
Forget the other modes for now. If I have a step response of a channel and
don't know the impedance (really s11, s22) how can I find system voltage
transfer function. In the frequency domain; for a channel, source, and load the
VTF is.
(Gamma_src-1)*s21*(Gamma_ld+1)
---------------------------------------------------------------------------------
1-s12*s21*Gamma_src*Gamma_Ld+s11*s22*Gamma_src*Gamma_Ld-s11*Gamma_src-s22*Gamma_ld
Gamma_src=Source reflection
Load_ld=load reflection
S11,s22,s21,s12 = 2 port channel s-parameter
This if is we consider all is linear.
...Rich
-----Original Message-----
From: Scott McMorrow [mailto:scott@xxxxxxxxxxxxx]
Sent: Thursday, November 19, 2009 12:17 PM
To: msteinb@xxxxxxxxxx
Cc: Mellitz, Richard; wkatz@xxxxxxxxxx; IBIS-ATM
Subject: Re: [ibis-macro] Re: FW: [IBIS-Users] AMI convolution
It seems to me that a 2-port interface from a driver or receiver to the
interconnect environment would be sufficient to characterize all
multi-conductor interconnect modes, assuming that there is no
driver-to-driver, receiver-to-receiver, or receiver-to-driver analog
interactions on the silicon.
Mike Steinberger wrote:
> Rich-
>
> The output of the algorithmic model is a one dimensional waveform. If
> you want to model modal behaviors, that will have to be done in the
> analog model. For example, that's where the S parameter behaviors you
> refer to are modeled; and depending on the EDA platform, those S
> parameters can be multiconductor.
>
> By the way, what important modes do you think should be modeled?
>
> Mike S.
>
> Mellitz, Richard wrote:
>>
>> Hi Walter,
>>
>> I was thinking about this some. Does this flow preclude a modal
>> impulse response flow? The single channel voltage transfer impulse
>> response really requires 4 entities based on s11, s21, s12, and s22.
>> A multi-conductor response requires more.
>>
>> ... Rich
>>
>> *From:* ibis-macro-bounce@xxxxxxxxxxxxx
>> [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] *On Behalf Of *Walter Katz
>> *Sent:* Wednesday, November 18, 2009 12:14 PM
>> *To:* IBIS-ATM
>> *Subject:* [ibis-macro] FW: [IBIS-Users] AMI convolution
>>
>> All,
>>
>> In case you are not in ibis-users@xxxxxxx .
>>
>> Walter
>>
>> Walter Katz
>>
>> 303.449-2308
>>
>> Mobile 720.333-1107
>>
>> wkatz@xxxxxxxxxx
>>
>> www.sisoft.com
>>
>> -----Original Message-----
>> *From:* Walter Katz [mailto:wkatz@xxxxxxxxxx]
>> *Sent:* Wednesday, November 18, 2009 12:00 PM
>> *To:* Eric Monteiro; ibis-users@xxxxxxx
>> *Subject:* RE: [IBIS-Users] AMI convolution
>>
>> Eric,
>>
>> Asking who is responsible for convolution is like asking who is
>> responsible for Fourier Transform. Convolution is a mathematical
>> technique that EDA tools can use on the input and output of AMI
>> models, and convolution is a mathematical technique that can be used
>> inside of the AMI model to apply a filter. The following describe who
>> may or must use convolution for the "Preferred Flows". Preferred
>> flows assume both the Tx and Rx model have Init_Returns_Filter=True
>> and Use_Init_Ouput=True.
>>
>> Assuming a preferred statistical flow, the EDA tool supplies an
>> impulse response of the channel to the TX Init function. Inside the
>> Tx Init function (i.e. inside the AMI model), the model would compute
>> an impulse response of its filter and return it to the EDA tool. The
>> EDA tool would convolve this impulse response with the impulse
>> response of the channel and present these results to the Rx Init. The
>> Rx Init would determine the impulse response of its filter, and
>> return it to the EDA tool. The EDA tool would then convolve it with
>> the impulse response that was presented to Rx Init to determine the
>> impulse response of the channel equalized by both the Tx an Rx
>> filters. The EDA tool will process this and may use the convolution
>> mathematic technique (e.g. on probability distribution functions) to
>> generate bathtub curves and bit error rates. So in the preferred
>> statistical flow the EDA tool does convolution and the AMI model
>> might not. I could image that the AMI models may use the convolution
>> technique to generate the impulse response of the filter.
>>
>> Assuming the preferred time domain flow, the EDA tool must first run
>> the statistical flow (it need not analyze the results of Rx Init).
>> The EDA tool supplies a stimulus waveform to Tx GetWave. The EDA tool
>> may or may not use the convolution generate this waveform. The Tx
>> GetWave will generate an equalized stimulus waveform with techniques
>> that may or may not use convolution. The EDA tool must us uses
>> convolution to apply the impulse response of the channel with this Tx
>> equalized stimulus waveform. The waveform is then presented to Rx
>> GetWave. Rx GetWave may or may not used convolution to apply its
>> equalization filter to it's input. The output of Rx GetWave is a
>> waveform, and clock ticks. The EDA tool may or may not use
>> convolution to analyze this waveform to generate bathtub curves and
>> bit error rate. So in the preferred time domain flow, the EDA tool
>> must use convolution, and the AMI model might not.
>>
>> Walter
>>
>> Walter Katz
>>
>> 303.449-2308
>>
>> Mobile 720.333-1107
>>
>> wkatz@xxxxxxxxxx
>>
>> www.sisoft.com
>>
>> -----Original Message-----
>> *From:* owner-ibis-users@xxxxxxx [mailto:owner-ibis-users@xxxxxxx]*On
>> Behalf Of *Eric Monteiro
>> *Sent:* Wednesday, November 18, 2009 10:55 AM
>> *To:* ibis-users@xxxxxxx
>> *Subject:* [IBIS-Users] AMI convolution
>>
>> Hi everyone,
>>
>> I was hoping someone could clarify who is responsible for convolution
>> in IBIS-AMI (EDA tool, or the modeler).
>>
>> Clearly the convolution involving an FIR filter is upon the modeler,
>> the convolution I speak of is the one that is done with the channel
>> response.
>>
>> My understanding has been as follows: (please correct me if I'm wrong)
>>
>> (a) -- (Tx IC) -- (passive channel) --(b)--(Rx IC)
>>
>> You force an impulse at (a), measure the response at (b). (b) is the
>> analog channel response hAC(t). GetWave then needs a wave, which
>> should be an ideal bit train, convolved with the bit period (creates
>> a piece wise linear wave) which is then convolved with hAC(t) to
>> produce the wave fed into GetWave. There was discussion as to whether
>> the modeler or the EDA tool should do the above convolution. Has it
>> been decided who this task falls on?
>>
>> Best Regards,
>>
>> Eric Monteiro
>>
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>
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