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LMX2572 phase noise figures

Muharrem Kara
Prodigy 110 points

Other Parts Discussed in Thread: LMX2571, LMX2572

Hello,

We are using LMX2571 in our applications. But, we need one with a better phase noise performance of at least 6 dB better than LMX2571's phase noise.

Therefore, i would like to ask a few questions about LMX2572.

At which OSCin frequency did you measure the phase noise figures of LMX2572 given in Figure 21, in the data sheet?

If we operate LMX2571 and LMX2572 under the same conditions, can we get better phase noise performance from LMX2572 output at 500 MHz ?

If we can, how much dB?

thanks and kind regards,

kara

  • 0
    TI__Expert 5370 points
    Dear Kara,

    This is an excellent question.

    LMX2572 is indeed a lower phase noise device.

    1) the figure of merit of LMX2572 for PLL noise floor (inside the loop bandwdith) is a bit better on LMX2572...
    2) However, LMX2572 will support a higher PFD (130 vs 250 MHz, 2.8 dB) frequeny allowing for better PLL floor.
    3) The VCO is also better with about 6 dB better PN at 1 MHz offset.

    I will say that figure 21 was obtained with a clean 100 MHz reference.

    I hope this helps.

    Regards, Simon.
  • 0 in reply to Simon Damphousse
    Prodigy 110 points
    Dear Simon,
    Thank you very much for your quick reply and interest.
    Kind regards,
    kara