Hello all,
Thanks for the replies, very helpful. Quick follow up if you don't mind. If I am understanding your replies and the LMK04208 datasheet correctly. If I use the LVDS type output I can use the diagram above and achieve proper termination? The connection between the 100 ohm resistor and Refin would be very short, <5mm.
Input Sensitivity 0.7 AV DD V p-p
Hopefully I am understanding what the input sensitivity means. It means the reference signal must be greater than 0.7 Vp-p but less than AVdd Vp-p? I have an eval board of the LMK04208. I measured the LVDS output (single ended) with the scope set to 50 Ohm termination and measured 440mVp-p. This falls below the required input sensitivity , however, if I combine the differential output through a transformer I should get 2x 440mVp-p? Which would meet the sensitivity spec.
The LVCMOS type output measured 1600mVp-p (single ended with 50 ohm termination). This output type would give me a much larger margin to meet the sensitivity spec. However, the LMK04208 datasheet says nothing on how to terminate LVCMOS correctly. I found some
other resources on how to terminate LVCMOS with simple 50 ohm transmission lines and 50 ohm resistors, however, all those resources were referring to single ended LVCMOS outputs. Would using the differential LVCMOS output be any different than my diagram above?
Better use a regular transformer, you definitely don't need multi GHz bandwidth in this application.
I only suggested the mini-circuits part because one of the Ti reps suggested one of their
own products to convert a differential clock to single ended. Could you recommend a more economical part? As you suggested I dont need 3 GHz bandwidth. The max clock signal I would be generating is 125 MHz.
Thanks again for your help and time.
Sami