Differential input accepting single ended signal

Hi Ahtran,

Differential ADN2917 output specs are different from single ended HMC856 and HMC726 devices. You will need to review the VIH/VIL specs for chip being driven by the ADN2917 in differential mode wrt single-ended spec from HM856 and HMC716. We can connect to one single ended device at a time but it violates the spec when we connect to two single ended devices. In general AIN+ can be used for single ended operation, check the HMC726 datasheet for the connectivity.

Thanks,

Siva Kumar.

Thanks Siva

Hi Siva,

I have another question.  If I want to connect the output of ADN2917 to the input of HCM856, can I use DC couple connection as shown below?  The ADN2917 is using a positive voltage rail, but the HMC856 is using a negative voltage rail, so I am not sure if DC couple is possible.

If AC couple is required, do I need to add 50 ohm pull-up to VCC on the ADN2917 side?

Thanks

Hi Ahtran,

Yes, you are right. DC coupling connectivity is not possible at the output section in this scenario and external pull-up required at output circuitry. AC coupling capacitors and pull-up resistors are must to be chosen such that the device should work properly without effecting the full data rates. Please refer to the applications information section in ADN2917 data sheet for choosing AC Coupling Capacitors.

Regards,

Siva Kumar.

Thanks Siva