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CDCE62005 Feedback divider vs feedback bypass divider.

Max Roh
Expert 4185 points
Other Parts Discussed in Thread: CDCE62005

Hi Clcok team,

I'm AIP FAE in korea. not an expert for clcok generator parts. so I'm now asking and want to help your team support.

Can you please let me know which is different "feedback divider" and "feedback bypass divider"?  or any documents? I need to get in detail.

when the feedback divider is used? and when the feedback bypass divider is used? thank you in advance.

Regards.. Max.

  • 0
    TI__Expert 3985 points

    Hi Max,

    I guess you are already referring to Figure 8 from the datasheet. Generally the PLL structure has just one feedback divider (FD). But. the CDCE62005 has a feedback divider (FD) and a feedback bypass divider (FBD). Since the VCO frequency range is limited inside 1.75 - 2.356 GHz, a more flexible and wider feedback division range is needed.

    For some application just the feedback divider can be enough. But there may be some application where you may need a feedback bypass divider too. The total division ratio would be the value of the feeback divider times the value of the feedback bypass ratio (FD*FBD). 

    For example a division ratio of 540 can not be achieve just by the feedback divider, but it can be achieved select the feedback divider to 108 and the feedback bypass divider to 5.

    The GUI for the CDCE62005 includes a tool called Frequency Planner where you can insert your input frequency and the requested output frequency; it will generate the device settings which are needed for the device. One of this setting are the FD and FBD value.

    I hope this could already help you.

    Best regards,

    Leandro