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PLLATINUMSIM-SW: Possible bug when showing spurs in Integrated phase noise

Jim George
Prodigy 100 points
Part Number: PLLATINUMSIM-SW
Other Parts Discussed in Thread: LMX2594

Hello,

I'm using v 1.5.2.0 of PLLatinumSim to simulate an LMX2594. When asking PLLatinum to plot the spurs in the integrated noise plot (using the 'Add spurs to Integrated Noise' checkbox under 'Other Integrated Noise Metrics' within the Phase Noise tab, the spurs seem to be scaled incorrectly. They are showing up at 1/1000 their original frequency. For example, in my case, the PFD frequency is 200 MHz. The Spurs tab shows a spur at 200 MHz, at -76.9 dBc. When this data is plotted within the Integrated Phase Noise plot, it shows up at 200 kHz instead. Interestingly, the tooltips for the spurs show the wrong frequency of 200 kHz (see below). This leads me to think that maybe the software simply forgot to multiply by 1 kHz, since offsets in the spurs tab are shown in kHz, while the phase noise plots are done in Hz.

Thanks,

-Jim

PS, what happened to the LMX2594 data sheets on TI's website? They were available till yesterday, now they're gone.

  • 0
    TI__Mastermind 28021 points
    Jim,

    Thank you for your feedback. Indeed, you are correct that the spurs on the phase noise chart are off by a factor of 1000. However, the integrated noise calculation is correct. I fixed this and it will go out with the next release of PLLatinum Sim.

    As for the datasheet, we just released a major update and it is being updated on the web. Give it about 24 hours and be sure to use this newer revision in the future.

    Regards,
    Dean