Hi! I'm trying to develop DAC+Amp for PC. There are PCBs for power, DAC and amplifier in my project. Should I separate digital and analog ground in power PCB or do it in DAC/Amp PCB? Is there necessary to separate digital ground from transformer also? What should to use for separating - ferrite bead or ferrite ring and why?
Did you mean separation is already done in the chip or AGND and DGND should split near chip pins?
The lowest impedance signal return path is the same as signal main path or the shortest path?
Use one ground plane...don't split them.
What chip are you using?
Current return paths...
http://www.x2y.com/filters/TechDay0...log_Designs_Demand_GoodPCBLayouts _JohnWu.pdf
Visible Return Current
Design News - Features - How Current Return Paths Affect Signal Integrity
What chip are you using?
Current return paths...
http://www.x2y.com/filters/TechDay0...log_Designs_Demand_GoodPCBLayouts _JohnWu.pdf
Visible Return Current
Design News - Features - How Current Return Paths Affect Signal Integrity
Hi! I use DIR9001 (receiver) + PCM1794 (DAC).
I done PCB using solid ground plane:
(bottom side)
Should I partially split ground on the top side like this?
Are any other advices?
Thanks for your help!
I done PCB using solid ground plane:
An externally hosted image should be here but it was not working when we last tested it.
(bottom side)
Should I partially split ground on the top side like this?
An externally hosted image should be here but it was not working when we last tested it.
Are any other advices?
Thanks for your help!
The key things to remember is to always try to minimise current loop areas, especially when fast signals are concerned.
Lay the board out as if you were doing a split plane, but don't actually split the plane is generally best practise for most things.
I would critique that board as trying to be overly pretty (especially with those long curved tracks leading to vias to the ground plane), a via right next to the pad is almost always better then one 10mm of skinny trace away.
Get some decoupler ceramics right at the pins, and where possible connect them to the relevant pins without involving a via (Going say from a part on layer 1 -> via to ground -> via to layer 1 > decoupling cap ground end is much worse then part on layer 1 -> decoupling cap for all that both nets have the same names).
Quite often you will find that a sensitive part is designed to allow a 0603 or similar cap to be conviniently placed with the power and ground pins in reasonably good alignment, take advantage.
Those enormous thru hole caps are mostly a wate of time for HF decoupling, a 100nF or so X7R 0603 or even 0805 or 1206 will stomp all over them in effectiveness simply due to smaller loop area and hence less inductance.
the advantage of placing all the IO on the same edge of the board is that everything has the same ground and is thus less likely to radiate once the cables get outside the case.
I worry about the missing reconstruction filter parts, without it you still have significant energy up into the RF on those analogue outputs just begging to get into things.
Regards, Dan.
Lay the board out as if you were doing a split plane, but don't actually split the plane is generally best practise for most things.
I would critique that board as trying to be overly pretty (especially with those long curved tracks leading to vias to the ground plane), a via right next to the pad is almost always better then one 10mm of skinny trace away.
Get some decoupler ceramics right at the pins, and where possible connect them to the relevant pins without involving a via (Going say from a part on layer 1 -> via to ground -> via to layer 1 > decoupling cap ground end is much worse then part on layer 1 -> decoupling cap for all that both nets have the same names).
Quite often you will find that a sensitive part is designed to allow a 0603 or similar cap to be conviniently placed with the power and ground pins in reasonably good alignment, take advantage.
Those enormous thru hole caps are mostly a wate of time for HF decoupling, a 100nF or so X7R 0603 or even 0805 or 1206 will stomp all over them in effectiveness simply due to smaller loop area and hence less inductance.
the advantage of placing all the IO on the same edge of the board is that everything has the same ground and is thus less likely to radiate once the cables get outside the case.
I worry about the missing reconstruction filter parts, without it you still have significant energy up into the RF on those analogue outputs just begging to get into things.
Regards, Dan.
Last edited:
Here next revision
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Investigate this now=)
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