AD9695 SYSREF DC COUPLED LVPECL TERMINATION

Hi

I'm driving sysref to AD9695 from HMC7044.

Since I use 1shot sysref it must be DC coupled. HMC can't work in LVDS mode for DC coupled 1shot sysref (known issue) thus forces me to work in LVPECL.

from HMC (driver) point of view, recommended termination is:

with DC parameters:

On the other hand, AD9695 requirements are:

So it seems that Vcm is at the edge of the upper value , and also swing.

How do you reccomend to connect?

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  • 0
    •  Analog Employees 
    on Sep 14, 2021 11:52 AM in reply to dobarak

    Hi,

    Yes, Vcc is 3.3V as it is the supply voltage of driver. Unfortunately, 1.8V is not an option because output of the driver is around 2.1V. 

    It is suggested to put the resistors close to receiver side in general. If the distance between the HMC7044 and the ADC is not too much, you can place the resistors close to driver side. Another option is to put first resistor to driver side and the other two close to receiver side. 

    Regards,

    Kudret

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