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LMX2582: High phase noise

Dhruv Goyal
Prodigy 20 points
Part Number: LMX2582

I am trying to generate a frequency of 751 Mhz but I am getting a high phase noise. I am using the following register configuration. Any suggestions to reduce the phase noise?

Reg-46 0
Reg-45 0
Reg-44 89
Reg-40 77
Reg-3e 0
Reg-3d 1
Reg-3b 0
Reg-30 3fd
Reg-2f cf
Reg-2e fa3
Reg-2d 38e2
Reg-2c a
Reg-2b 0
Reg-2a 0
Reg-29 4240
Reg-28 f
Reg-27 8204
Reg-26 48
Reg-25 4000
Reg-24 421
Reg-23 29f
Reg-22 c3ea
Reg-21 2a0a
Reg-20 210a
Reg-1f 601
Reg-1e 34
Reg-1d 84
Reg-1c 2924
Reg-19 0
Reg-18 509
Reg-17 8842
Reg-16 2300
Reg-14 12c
Reg-13 965
Reg-e 18c
Reg-d 4000
Reg-c 7002
Reg-b 18
Reg-a 10d8
Reg-9 302
Reg-8 1084
Reg-7 28b2
Reg-4 1943
Reg-2 500
Reg-1 809
Reg-0 2218

Thanks

  • 0
    TI__Mastermind 33790 points

    Hi Dhruv,

    I looked at the config in TICS Pro and I didn't see anything that stood out. You may want to set output B to channel divider, even though it is powered off; this sometimes helps with noise reduction.

    Without knowing what the phase noise plot looks like, I can't say for certain whether the noise you're seeing is high. Have you confirmed against PLLatinum Sim for the same case? What are your loop filter coefficient values?

    Regards,

    Derek Payne