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Need help with selecting parts.

Other Parts Discussed in Thread: LMX2571, LMX2582, LMX2594

Hi,
we need help with selecting parts. We need a PLL (preferably with integrated VCO) which can output sine-wave in the range of 0.3~1 GHz. Does TI has such an IC? Thanks a lot!
Best,
HP

  • Hello Han,

    thank you for your interest in our PLL. We multiple PLL for this job.

    LMX2571 for low power

    LMX2582 for high performance with outstanding VCO low noise

    LMX2594 for sync capability with outstanding PLL low noise

    All have integrated VCO.

    You can use our tool Pllatinum Sim (free download on ti.com) to select a device based on your requirements.

    Let us know if you have more questions.

    Regards, Simon.

  • Thank you Simon for your support.

    Take LMX2582 for example, It's a nice chip. Its VCO core covers an octave from 3.55 to 7.1 GHz, for our desired frequency range (0.3~1 GHz) the output channel dividers have to be involved which means the output is a square-wave if I understand it correctly. However, what we need is a sine-wave output. Of course we can add additional LPF for that purpose but a direct sine-wave output is more desirable. Do you have any recommendation?

    Another requirement from our project is we need perfect phase alignment between the output and the reference input. From thread, it seems the output phase might become not coherent with the reference signal when changing the frequency. Could you please confirm LMX2582's performance on the phase coherence between the output and the reference input?

    Thank you!

    Best,
    HP

  • Dear Han,

    You are correct. the output is not a controlled low distortion output sine wave. I do not know your exact requirements but it sounds you will need to "format" the signal to obtain the desired sine wave you are looking for. Our PLL do not have "low distortion" sine wave. For the range of interest you could likely be able to do that with 2 LPF.

    Regards, Simon.
  • Thanks Simon.

    What about duty cycle? Is it assured always to be 50% at the output?

    Please support regarding the phase coherence issue. Thanks a lot!

    Best,
    HP
  • most output are 50/50 except for example /3 with LMX2582.

    Phase cohenrence with output devider is supported on LMX2594.

    Regards,
    Simon.