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CDCE62005: External Loop Filter

Ryan Meruvia
Prodigy 60 points
Part Number: CDCE62005

Hello,

I am wondering what the uses for the internal and external loop filters are. I am planning on outputting a 1 GHz clock from the CDCE62005, what resistor and capacitor values should i use for the internal or external loop filter in this case? Thank you!

Regards,

Ryan

  • 0
    TI__Genius 16845 points

    Hi Ryan,

    The configuration of the loop filter will impact whether this device performs as a clock synthesizer or a jitter cleaner. You may find the following app notes helpful:

    Here is a procedure for designing a loop filter using the CDCE62005 EVM GUI:

    1. Press the button "Loop Filter" in CDCE62005 EVM GUI
    2. Input "Phase Margin"  between 45~75 degrees
    3. Select " loop bandwidth" ( normally < Phase Detect Frequency / 15 ). If the input reference clock is noisy, a narrow loop bandwidth could achieve better jitter performance.
    4. Check "Standard Value"
    5. Press the button "Suggest RC's". You may get new RC's value. If there is no exact R or C in hand, select a close value. Then press the button "Calculate Output (Using RC Input)" to update Phase Margin (PM) and Loop Bandwidth (LBW). Make sure that PM and LBW are still in the range of step 1 and 2.

    I hope this information helps

    Kind regards,
    Lane

  • 0 in reply to Lane Boyd
    Prodigy 60 points

    This is extremely helpful! Thank you!