Forum Post: RE: AFE5809: Question on Differential termination resistor location for ADC clocks input

Hi Yi, How are you? Thanks for using AFE5809 device. for your question #1, the AFE5809 differential inputs have very high impedance (around 100KHz differentially). Please look at the data sheet page 46. figure 79. (b) ADC Input Clocks. for your question #2, could you please let us know where you found: ----------- But I also see some design as "Clock source--> AC caps--->100ohm --> AFE" . ----------- for the question #3, Yes, please place differential 100ohm and AC caps as close to the AFE5809 clock input pins as possible. This helps the clock signal trace 50ohm impedance matching purpose. Thank you very much! Happy New Year! Best regards, Chen