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sinara-hw / FMC_Shuttler

16-channel 125MS/s 16bit DAC in FMC form factor.
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missing decoupling capas at the IC72 #7

Closed gkasprow closed 3 years ago

gkasprow commented 5 years ago

There are FB connected to the supply pins. Aren't there missing decouplig caps?

gkasprow commented 5 years ago

can the VOCM be left dangling?

dhslichter commented 5 years ago

VOCM for the ADA4927s needs to be tied to ground.

tprzywoz commented 5 years ago

VOCM for the ADA4927s needs to be tied to ground.

Done

There are FB connected to the supply pins. Aren't there missing decouplig caps?

Added according to datasheet: 1nF 100nF ceramic and 10uF tantalum capacitors for each supply.

dhslichter commented 5 years ago

Added according to datasheet: 1nF 100nF ceramic and 10uF tantalum capacitors for each supply.

Please make notations for voltage and dielectric spec (X7R or NP0) for the ceramic caps. These amps may be driving a reasonable amount of current into the terminated transmission lines and so we want to make sure we don't have dc bias issues with the capacitors.

gkasprow commented 3 years ago

it's not relevant anymore. we don't have any caps in the signal path in the FMC project. I added a note on the AFE schematics