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Re: [802.3_10SPE] On the inductance and capacitance limits of a T1S (d2.0, c147)

Dear All,
As per the email of Chad asking where this comment was coming from, allow me please to:
Should you:
Yours sincerely
From: Huszak Gergely
Sent: Monday, August 27, 2018 2:00 PM
To: STDS-802-3-10SPE@xxxxxxxxxxxxxxxxx
Subject: On the inductance and capacitance limits of a T1S (d2.0, c147)
Dear All,
During the resolution of certain competing comments on the inductance and capacitance limits of a T1S (Table 147-3) we ran into some contradictions between the comments, plus experts sensed the danger of possible misunderstandings lingering around these topics (more precisely what each value exactly means and how these may influence PoDL solutions), thus allow me please to:
- send you one of the notable comments in question (below)
- draw your attention to the good work/presentations that have already been done on this topic:
- kindly ask anyone interested to present before (next ad-hoc this week) or during the Spokane meeting. For now we are already expecting presentations from Tim Baggett, David Brandt and Scott Griffiths, and Piergiorgio Beruto
Yours sincerely
Comment: MDI impedance limit parameters need adjustment.
As PoDL will not be used, inductance should not be required, and therefore eliminated.
Also, additional capacitance may be needed to filter out higher frequency noise. A LPF with 3dB cutoff should be more than 125 MHz (10x the DME frequency) results in the need for 25.4pF of differential capacitance.
Remedy: - Remove the Inductance parameter, or reduce L (minimum) to 0.
- Change Cnode to 25 pF (maximum)
- Change Ctot to 250 pF (maximum)

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