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AD9690 CLK input by ac-coupling LVDS

Question asked by sss on Feb 26, 2016
Latest reply on Mar 28, 2016 by UmeshJ

Hi all,

 

Our customer will consider the CLK input configuration at AC-Coupled LVDS, from AD9528 to AD9690.

 

Q1.

Which layout is correct ?

a. LVDS CLK+/- >>> 100 ohm termination >>> ac-coupling cap >>> CLK IN

or

b. LVDS CLK+/- >>> ac-coupling cap >>> 100ohm termination >>> CLK IN

 

I think "a" is correct, because of the current pass.

If we configure the EVB clk circuit for ac-coupling LVDS, termination use the R810/811 @ 100 ohm, and remove the B805 ?

 

 

In the datasheet @ AD9690,

AD9690_LVDS.PNG

 

In the EVB schematic @ AD9690,

AD9690EVB_LVDS.PNG

 

and in the datasheet @ AD9528,

AD9528_LVDS.PNG

 

Best regards,

sss

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