Should I use ground plane for Butterworth low pass filter?

[Charles999]

when avoid ground plane

Hi all

I usually use ground planes extensively top & bottom, but on a mixed analogue/digital board I need to have a Butterworth low pass filter - should I avoid any ground plane around this so as not to influence too much the L's & C's?

App is a DDS sig gen, lo pass to ~ 70Mhz

Thanks for any info,

Charles

 

[Iouri]

Ground plane or not?

Make the separate ground for the digital section and analog, connect them together under your CODEC. Also make sure to separate power as well, and use atleast simple LC filter to power your analog section

Good luck

 

[shwoo]

Re: Ground plane or not?

I agree. Separtion of Digital and Analog is more important.
L and C value changes due to ground plane can be small
at 70MHz and below.

 

[GK]

Re: Ground plane or not?

Hi,

1.Try to isolate the Analog and digital area, when you are going to pour the copper.
2. Also don't route any trace across the pour area. If you desperately wanted then, provide 3*Width of the line gap between the pour and your traces.

I hope this suggestion would improve your quality of the board without affecting the performance.

GK

 

[Nimer]

Re: Ground plane or not?

hi

i agree with the above and suggest the same .

regards