ad9648 can't start work

we used two pieces of ad9648 on our project .

the problem is that there is a certain probability that ad9648 can‘t start work,for example,you boot it 100 times, 20 times the ad9648 wouldn't start work.


the FPGA give the differencial clock to the ad9648,the PI6C485311 is a 1-to-2 Differential to LVPECL fanout buffer.

we found that changing the R43 and R62 have the efffect on result.

R43=R62=240Ω,the clk Vpp=250mv, about 20% possibility ad9648 can‘t start work.

R43=R62=24Ω,the clk Vpp=400mv,about 5% possibility ad9648 can‘t start work.and some of them are always able to start work

R43=R62=100Ω,the clk Vpp=800mv,about 50% possibility ad9648 can‘t start work.


how to change the R43 R62 can solve the problem ?