LMX2694EPEVM: LMX2694EPEVM phase noise test

Hi Jin,

After plugin your reference clocks phase noise in the simulation tool, the result with 100Mhz agrees with simulation. Again the result with 10MHz does not agree with simulation. 

The reason is, although your 10MHz reference clock phase noise is good, but it is a sine wave. A sine wave clock at 10MHz means its slew rate is very bad.

PLL is sensitive to the slew rate of the reference clock, poor slew rate will hurt PLL noise. 

You can try, using the 100MHz reference clock in your second configuration, phase noise will become much better.