DS25BR110: The input common mode voltage at AC-coupled

Hi team,

Any update on this issue?

I am waiting for updates of information.

Best regards,
Tomoaki Yoshida

Hi,

Sorry for the delay.  If possible it is best to connect the DS25BR110 without AC coupling.  The LVDS receiver has a wide common mode voltage range and can handle most signals directly.  In many cases AC coupling without any bias has been successful.  Adding an external common mode voltage bias would provide additional noise suppression. I recommend to provide the external bias be to ~ 1.2V, I would bias the inputs with a ~1K external impedance to avoid shifting the total input termination impedance too far from 100 ohms.  

Regards,

Lee

Hi Lee-san,

Thnak you for your reply.

In the case of AC coupling, is it possible to use without any bias?

In other words, is there a bias circuit inside of IC?

Best regards,

Tomoaki Yoshida

Hi Tomoaki-san,

There is not a low impedance bias on the input of the device.  In my experience the DS25BR110 tends to float down to GND when not externally biased.  This solution works well in the lab.  For a system with more noise, I would at least put an option in the schematic to bias the DS25BR110 input.  Biasing to GND is okay as well, this would eliminate the need to develop any other voltage level.

Regards,

Lee

Hi Lee-san,

Thank you for your support.

I understood about bias circuit.

Since we care about noise, we will examine the external bias.

Best regards,

Tomoaki Yoshida