For high speed, you want more decouple cap and termination resister and cap... not less.  Or you can do simulation plus full frequency test to find out. It will be scary, one way or the other.   (depend upon what frequency you use)...

Sent from my BlackBerry 10 smartphone.
  Original Message  
From: Peter G. Houwen
Sent: Thursday, June 15, 2017 15:23
To: [log in to unmask]
Reply To: TechNet E-Mail Forum
Subject: [TN] Diving into Embedded Capacitance

(maybe)

We're embarking on a new design that appears to be a great candidate for embedded capacitance (mixed high speed & RF). We've never used it before. Because this project will be very high profile within the company, and we have a very condensed development schedule, I don't want to introduce risk that can't be managed. My theory is that we already have a high risk of not passing FCC for radiated emissions, EC might be a lesser risk as the minimized harmonics will be a great help.

But I don't know HOW risky it is. What if I don't have space for all the caps we left off counting on the EC? Is there a way to calculate what caps CAN be safely removed? Is the capacitance benefit often theoretical, or always real world?

I'm kind of sticking my neck out here, I'm just not sure how safe that might be.

Thanks!

Pete