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How to seperate analog and digital parts on one chip?

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BillQ

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Hi,

if the analog and digital circuits on one chip share the same substrate.

As the digital part generates large switching noise. Guard rings are added to seperate them.

But besides the guard rings, is there any other effect meaning to separete them?
 

can you use two ground pad? one for digital part,and another for analog part
 

Hi,
I am a PCB Designer, I have one doubt, Please help me,
If Digital and analog signals in the same chip how will u route that chip in PCB.

Thanks in advance.
 

BillQ said:
Hi,

if the analog and digital circuits on one chip share the same substrate.

As the digital part generates large switching noise. Guard rings are added to seperate them.

But besides the guard rings, is there any other effect meaning to separete them?
Click to expand...

Hi,

One method as you mentioned is the use of guard rings. We can surround both the Noisy block (Digital) and the sensitive block ( Analog) using gurad rings.In case if you want high protection you can use double and triple gurad rings also.Another method is the use of separate power and ground lines for digital and analog. Giving space between the two blocks also do good.This you can decide in floor planning itself.From design point of view reducing the voltage swing reduces the noise as well.If possible you can go for that also. For avoiding the noise you can use shileding using ground or Vdd or coaxial shielding and decaps.
Regards,
 

the best way besides guard rings is making two ground planes one analog and the other one digital..
as it gives proper isolation to noisy and sensitive block.

If Digital and analog signals in the same chip how will u route that chip in PCB
Click to expand...

prepare both the planes analog and digital and stitch them using a 0 ohm resistor which is as good as a jumper
 

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