This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMX2694EPEVM: LMX2694EPEVM phase noise test

Part Number: LMX2694EPEVM

TI Measurement data 2023.1019.pptx

I used the LMX269EPEVM product
And calculated using Platinum sim, but there is a big difference between the calculated and measured values.
So I want to know why.
Please check the attached file for the contents

  • Hi Jin,

    Could you provide the phase noise of your 100MHz reference clock source?

  • i used " bliey NV26R891 100mhz" bliley.pdf

  • 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.

  • We've confirmed the reference frequency at 10 MHz

    Let's measure 10MHz as a square wave. (DRA over-input)