• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 20 subscribers
  • Views 92 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

LMX2594: 125M and 125M harmonics

jianjun lu
Prodigy 50 points
Part Number: LMX2594

LMX2594, there are reference clock 125M and 125M harmonics in the output signal, with amplitudes below 70dbc. Is this normal? If it is abnormal, how can it be resolved?

  • 0
    TI__Guru* 89110 points

    Hi Jianjun,

    If your fpd is also equal to 125MHz, then the spurs could be due to fpd. You should use a smaller charge pump current to reduce this spurs.

    In addition, if CAL_CLK_DIV =  0 (div/1), the internal state machine clock is also running at 125MHz. After the PLL is locked, you can set R2[10] = 0 to disable the state machine clock, this would reduce the 125MHz spurs at the output. Remember, before you are going to calibrate the VCO, you have to set this bit back to 1.