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Design >> RF Design >> down-bond
https://designers-guide.org/forum/YaBB.pl?num=1229412342

Message started by aaron_do on Dec 15^th, 2008, 11:25pm

Title: down-bond
Post by aaron_do on Dec 15^th, 2008, 11:25pm

Hi all,

I have a receiver design with a RX and a PLL. I'm worried that if the RF section shares the same ground as the digital dividers of the PLL, then a lot of noise will couple to the RF section due to the substrate resistance. So I have the option of down-bonding either the digital divider's ground, or the RF section's ground, and using a separate pin for the other ground. Just curious, which one is better? Should I down-bond the digital divider ground, or the RF section, or should I just connect them both to the down-bond?

thanks,
Aaron

Title: Re: down-bond
Post by loose-electron on Dec 17^th, 2008, 3:09pm

Suggestion: Put together a simplidfied model for this:

Behaviorals with the typical surge currents in the pins/connections and a bonding and package model, with a dummy resistance between the two grounds and investigate your options quantitatively?

Using that you can develop a systematic method to investigate your options.

My guess is that a low impedance grounding structure on both sides will be the best performing, but this will give ypu a method of checking it out.