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Re: [802.3_50G] 802.3cd: Jitter Question

Adee, Piers,

I don't think the +/-100 ppm spec. can be used to calculate peak-to-peak LF jitter.

One could use a +/-100 ppm crystal oscillator on the host, which could operate at either edge of the spec. range. The LF jitter effect should be in addition to the +/-100ppm impairment.



On 01/17/2018 11:33 AM, Ali Ghiasi wrote:

Typically DC-DC convertor will have one dominant tone output like 3rd or 5th harmonic, etc.  Given today efficient DC-DC convertors operates at > 1MHz 
it is much easier to filter the spurs with reasonable size low-ESR capacitor, which was not the case when DC-DC convertors operated at 50 KHz!

Obviously >1 MHz DC-DC convertor can’t generate multiple of UIs into SerDes output and pass limits we already have in place!

Ali Ghiasi

On Jan 17, 2018, at 10:16 AM, Bill Kirkland <wkirkland@xxxxxxxxxxx> wrote:

The analysis was done analysing a single tone.
Is it possible to get a bad spur from tones from a switching power supply that could influence the behavior in the analysis?