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LMX2491: Selecting PLL spot frequency resolution(in terms of hz, CW Mode)

prateek hegde
Intellectual 380 points
Part Number: LMX2491

Dear all,

We are trying to make the PLL to operate in particular frequency per say X Hz, After some time we want to change to X+delta Hz. What is the minimum delta Hz Possible with this chip.

Ex : Assuming we are operating the chip at 6.4 Ghz CW mode for some time, after that we need to change to 6.4Ghz + delta Hz . what is the minimum delta possible in CW mode.

Thanks in advance.

Prateek Hegde

  • 0
    TI__Mastermind 28550 points
    Hello Prateek,

    So the minimum frequency delta would be 1/16777216 * phase detector frequency (PDF). So if you had a 100 MHz PDF, you would have a frequency delta of ~6 Hz. But if the PDF was 10 MHz, that would be ~0.6 Hz.

    Now in your example, you are technically violating the maximum Fin frequency by increasing beyond 6.4 GHz.

    73,
    Timothy