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Re: [10GBT] PAM8 and PAM12 sys time domain analysis


Thanks for the input.

Please note that I'm not particularly religious about which transmit
filtering method to use so long as we can meet emissions requirements
comfortably. Therefore, I'm considering co-opting the fine transmit
filtering method proposed in powell_1_0704.pdf to use in a PAM8 system - I
think it's about time I take something from Scott, for a change :-). Having
said that, I've several questions and comments on your simulation results.

1. In the first paragraph, you state "Study systems including PAM8
@1GHz...., and an exemplary PAM12 system@825MHz. The latter was derived by a
simple frequency scaling of respective elements in the PAM8 system". My
question is why didn't you study the actual PAM12 system proposed in

2. On the forward equalizer frequency response plots on Page 3 (Figure 1),
why are there such huge ripples in the FFE responses? In contrast, there are
no such ripples in the FFE frequency response plots shown on slide 24 of

3. On the same figure, why does the PAM8 FFE frequency response tail off
very slowly towards fs/2 whereas the PAM12 FFE frequency response drops
about 10dB lower at fs/2?

4. For Model 3, the DFE SNR Margins computed using solarsep_varlen7a.m are

PAM8: 5.2dB relative to 19.9dB for 1E-12 BER
PAM12: 5.7dB relative to 23.8dB for 1E-12 BER

From the SNR at the slicer that you are computing (Table 2 on page 2), I get

PAM8: 1.0dB relative to 19.9dB for 1E-12 BER
PAM12: 0.27dB relative to 23.8dB for 1E-12 BER

From this, it does appear that your simulation results are supporting my
contentions on PAM8 vs. PAM12.

Sailesh Rao.

>From: Albert Vareljian <albertv@IEEE.ORG>
>Reply-To: "IEEE P802.3an" <>
>Subject: [10GBT] PAM8 and PAM12 sys time domain analysis
>Date: Mon, 26 Jul 2004 19:57:28 -0700
>Hi All,
>Pls find attached pdf report on PAM8 and PAM12 systems
>time domain simulation and comparative analysis.
>Albert Vareljian
><< PAM8_PAM12.pdf >>

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