Re: [802.3_B400G_ELEC] Topic: Floating taps for Rx FFE

Thread Links	Date Links
Thread Prev	Thread Next	Thread Index	Date Prev	Date Next	Date Index

Thread Links

Date Links

Thread Prev

To: STDS-802-3-B400G-ELEC@xxxxxxxxxxxxxxxxx

Subject: Re: [802.3_B400G_ELEC] Topic: Floating taps for Rx FFE

From: Richard Mellitz <000014533bad0b9c-dmarc-request@xxxxxxxxxxxxxxxxx>

Date: Fri, 22 Mar 2024 19:00:21 +0000

Accept-language: en-US

Arc-authentication-results: i=2; mx.microsoft.com 1; spf=pass (sender ip is 51.81.185.125) smtp.rcpttodomain=listserv.ieee.org smtp.mailfrom=samtec.com; dmarc=pass (p=reject sp=reject pct=100) action=none header.from=samtec.com; dkim=none (message not signed); arc=fail (47)

Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=samtec.com; dmarc=pass action=none header.from=samtec.com; dkim=pass header.d=samtec.com; arc=none

Arc-message-signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=qaIclmY78Ct0XfFd0gsClmMb+ucoGDnWErJkAdJiHtc=; b=OGKjVhzTGmj3DI1nyzYwBYdVj/e7w0MEa/TQ+1dv1yl+TKAqZyny2QImQHBS7ZLFMtRVaEJ4OOTkmOB0ItbYvso48VZ+uTn2wMk4r3FbQXzgdkUupOVx+Icw3TpfWzdi6XvQzIV2CjTwbNCd98E7OqdynIHgblqapLju6rUPR4CH1jyj/HR0nPTBKTacudxzHA5Ktv2bH3Xziqdi5OST03J5PHJqcP5Ww0dgz25rqg7G3pNywfCwDZfpDrm/YeYvrx+CriQpRVjR3Ia99YoDA/QLHfi+jAb/ffOEPtuOy0g5nDBCdAuXqCKPu9YSqi5sWyKf0a9R+54Sp9BdKjajQQ==

Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=juarst6MDpc+PswUjJ7Ohh7g+wDg9Fu1mRPUu/MjbgU=; b=fXux8h0GnkhyUztX2sR5n1etn/SW0GLkjv3m2fCm0gWjPmgOf5fOjZ1yWV0SVubQ+Fo5BGC+LNw8WbFhWstJONsbayhsGMX0QnfHxA4jhqm8hY255U7TUecTXw2833KvtI+vBpfhqcegmuSH04GqddXNY1c0LwaPYhyuxnd9aDgw4Vwl6YlKevgB3cAA2HCtbmVcs7bv1E+wsSg+v//wNTiciPne+3lA+ID6iDQAbia1U17lAfISdQDK578Zpdc06kUX/4ppAwvd9M9g654nyLb4pFmwGogqEMwdI86g1AxEn8oCU5LP7emLGGfO4Tz5rmhBxkznKHOUFg7wsXTz6g==

Arc-seal: i=2; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=fail; b=RKCE3ofmm+Lu5ZOjccn/UHgsBqFB2BPwVuLGyASPS9PvO5kchNHe1DyisJ8VjcDckOJJSwERh8+07BWirqekbqBfxTBqtR8NRR6gyAJogAZP/36QJ15ryJ8zlDT6fhOw+NaJGf4QuasF5JCZinm41c0wRK2Gu3K1rKqoWRAmVNvWwEdD3TX/6DIsyNj4MuOu7Jc7Ksrj3xO4oA2vtzOT7KfchDIZDostfROih2JOaY3aY4jtUPpk/WjybmSZOxOCs2+xzYln2i1nkRgVHPV4ha+gU67ounfe/2jnfDQAnl3lDutX1O+wSXAU1DpswZYjBgIXXXSfjXR0DymEoWckkg==

Arc-seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=Zbsi5BAidzIIXH02Sc76Vz1e8LdZ1NS3B/FwZXPrplsX/7nTrvIuVvCb8FwjdxPUp/wtbqv66RdG29bYiGHl8/1BQxVAvWRale3kHKKgS80AhP3i2nzEwHczQABw7BDoQG7sdCx4oRG3XlRv2IcghphS4P5WlkNrc5m5GPZV8DHu4qBXsxLwl1q3eeJdqWri3u6kwfB4jh/RwVH83FOGSxs2xhEmgV6CkEqvFTaBUI2Z92THoCvW7e9e2RQ69FahR3Ogxcz1Q8LVjztDkMTMgyMzn3cbSckVwHu+bXCcTA6okKO3EBiVoVArnEBVkSkc2NaoL/hCiuGjM0NePiRTgg==

Authentication-results-original: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=samtec.com;

Delivered-to: mhonarc@xxxxxxxxxxxxxxxx

Delivered-to: STDS-802-3-B400G-ELEC@xxxxxxxxxxxxxxxxx

In-reply-to: <CANEPSR=D4pfSL_3N16-A6aJkijJ3pFaAXtBQFUt1fzBf5A1GyQ@mail.gmail.com>

List-help: <https://listserv.ieee.org/cgi-bin/wa?LIST=STDS-802-3-B400G-ELEC>, <mailto:LISTSERV@LISTSERV.IEEE.ORG?body=INFO%20STDS-802-3-B400G-ELEC>

List-owner: <mailto:STDS-802-3-B400G-ELEC-request@LISTSERV.IEEE.ORG>

List-subscribe: <mailto:STDS-802-3-B400G-ELEC-subscribe-request@LISTSERV.IEEE.ORG>

List-unsubscribe: <mailto:STDS-802-3-B400G-ELEC-unsubscribe-request@LISTSERV.IEEE.ORG>

References: <CH3PR16MB594642FF28D75840688AACB49E322@CH3PR16MB5946.namprd16.prod.outlook.com> <CANEPSR=D4pfSL_3N16-A6aJkijJ3pFaAXtBQFUt1fzBf5A1GyQ@mail.gmail.com>

Reply-to: Richard Mellitz <Richard.Mellitz@xxxxxxxxxx>

Thread-index: Adp7mP7MxeFLvHFlRaGQymuXuRg6AwA8YuaAAAAekDA=

Thread-topic: [802.3_B400G_ELEC] Topic: Floating taps for Rx FFE

It does not appear to be a simple method. It does need looking into.

… Rich

Richard Mellitz

Samtec Southeast

Office: 803-908-4411

www.samtec.com

From: Adam Healey <adam.healey@xxxxxxxxxxxx>
Sent: Friday, March 22, 2024 2:56 PM
To: Richard Mellitz <Richard.Mellitz@xxxxxxxxxx>
Cc: STDS-802-3-B400G-ELEC@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_B400G_ELEC] Topic: Floating taps for Rx FFE

Your observations suggest that there is an issue with the implementation of the "FOM method" and, in my opinion, efforts should be focused on correcting the implementation rather than adding options for alternatives.

I say this because, by definition, a search that optimizes FOM should always result in the best FOM and I do not immediately see anything inherent to a FOM-based search that would result in "blocking" issues.

On Thu, Mar 21, 2024 at 10:22 AM Richard Mellitz <000014533bad0b9c-dmarc-request@xxxxxxxxxxxxxxxxx> wrote:

Hi All,

In COM 4.4 there are 2 selections to compute the floating taps controlled by the following spreadsheet table entry

RXFFE FLOAT CTL

ISI

FOM o ISI

If there are 1 or 2 groups of tap the FOM method may be as good or better than the ISI method invoked respectively by functions “ findbankloc” and “ FOM_rxffe_floating_taps”.

However, 3 or more groups may exhibit a search blocking issue for FOM which ISI method does not have.

In many cases I have seen the ISI method yield a slightly better ( a few hundredths of dB) FOM than the FOM method.

I was thinking of checking both methods unless someone has a better idea for the FOM method that accounts for blocking better.

Thoughts,

… Rich

Richard Mellitz

Samtec Southeast

Office: 803-908-4411

www.samtec.com

To unsubscribe from the STDS-802-3-B400G-ELEC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-3-B400G-ELEC&A=1

To unsubscribe from the STDS-802-3-B400G-ELEC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-3-B400G-ELEC&A=1