ADC3443: When I use FPGA LVDS driver pin for SYSREF , do they need Coupling capacitor?

Masaya Terashima

Part Number: ADC3443

Hi,

We will use the FPGA's LVDS driver to drive SYSREF.

The output characteristics of this driver are 1.25V common mode voltage and 0.25 ~ 0.6V differential swing.

I realized in past thread that this circuit requires an external termination resistor.

Is coupling capacitor also necessary? (Because SYSREF has internally 0.9V-bias)

Regards.

0 dBrock over 4 years ago

Hi Masaya,

Yes, it is recommended to AC couple SYSREF because of the internal biasing that you have mentioned.

Best Regards,

Dan

0 Masaya Terashima over 4 years ago in reply to dBrock

Hi Dan,

Thanks for the quick reply.

We make the connection AC-coupled.

By the way, is it NG to connect directly without an AC couple?
※As future knowledge

regards.

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