DC floating section - Githubissues

sinara-hw / Urukul

4 channel 1GS/s DDS (AD9910 or AD9912 variant)

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DC floating section #57

Closed dtcallcock closed 3 years ago

dtcallcock commented 3 years ago

The section between C49 and C50 has an undefined DC potential. I always thought this was to be avoided. Though I can't find a good reference for why this is bad right now (dC/dV of caps?, making an antenna?), so I am happy for someone to tell me it doesn't matter. Solution would be a BOM change to make default C50 population a 0R.

gkasprow commented 3 years ago

At least such configuration cannot be simulated using SPICE:) I don't know any mechanism that caps could build-up DC voltage causing significant change to their capacitance.

dhslichter commented 3 years ago

agreed that default BOM change to make C50 a 0R would be the way to go here.

dtcallcock commented 3 years ago

Despite my failure to articulate much beyond 'it gives me bad feelings', I don't think there is any good reason TO have two caps in series like this. But obviously can wait until BOM needs changing anyway.

gkasprow commented 3 years ago

fixed