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Design >> High-Speed I/O Design >> Noise isolation using back to back diodes across different power domains
https://designers-guide.org/forum/YaBB.pl?num=1384554355

Message started by bouehou on Nov 15^th, 2013, 2:25pm

Title: Noise isolation using back to back diodes across different power domains
Post by bouehou on Nov 15^th, 2013, 2:25pm

Hi,
I was reading some documentation on ESD designs today and came across something that I don't quite understand. The text said that the back to back diodes used across different power domains provide noise isolation.

Can someone explain that to me or point me to some reference material?
How exactly is the noise from the different domains isolated?

Thanks.

Title: Re: Noise isolation using back to back diodes across different power domains
Post by aaron_do on Nov 21^st, 2013, 6:06pm

Are they talking about substrate isolation? Analog and digital domains are usually substrate isolated using back to back diodes...

Aaron

Title: Re: Noise isolation using back to back diodes across different power domains
Post by bouehou on Nov 29^th, 2013, 8:50am

They were actually talking about substrate noise isolation. From what they're talking about, the back to back serves two purposes. It allows an ESD network to be designed for chips that have multiple power/gnd domains and at the same time provides substrate noise isolation. So I just stuck a back to back diode in my design and it's fine except at a semiconductor physics level, I'd like to visualize or understand how we achieve the noise isolation.

Thanks for your response.