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ADN2812 CDR

=== ADN2812 CDR ===

The LOL (loss of lock) of ADN2812 is asserted around every 200ms for short  period in our system.

The datasheet shows it will return frequency acquisition mode when frequency difference between VCO & incoming data over 1000 ppm. The LOL is asserted in frequency acquisition mode.

Suppose the jitter of our system is over 1000ppm sometimes, and under 1000ppm at most of time.

Is it possible to extend the criteria to return frequency acquisition mode from 1000ppm to 2000ppm, 5000ppm. Or something likes that. Thanks.

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  • Dear Gavinwang,

    Thank you for your replies.

    Now, let me understand

    1.   What is the input signal scheme, a PRBS 31 signal in NRZ encoding?  If not, please elaborate your input signal;

    2.   how you connect your input signal to the ADN2812, through DC interface or a AC coupled interface?

    3.   Is this input signal in a continuous mode or pulse mode? Pulse mode means even the signal is at 400Mbps, but it has a lower pulse modulated together.

    the pulsed signal turns on or off the 400Mbps signal.

    My concern is, your input signal might be something else rather than a  required continuous mode, 400Mbps signal, in PRBS 7 or 31, encoded in NRZ.

    In general, if your input signal is a pulsed signal, ADN2812 would easily see LOL toggles, and no lock to the input signal.

    Please confirm what input signal you applied to the ADN2812.

    Best Regards,

    Dongfeng

Reply
  • Dear Gavinwang,

    Thank you for your replies.

    Now, let me understand

    1.   What is the input signal scheme, a PRBS 31 signal in NRZ encoding?  If not, please elaborate your input signal;

    2.   how you connect your input signal to the ADN2812, through DC interface or a AC coupled interface?

    3.   Is this input signal in a continuous mode or pulse mode? Pulse mode means even the signal is at 400Mbps, but it has a lower pulse modulated together.

    the pulsed signal turns on or off the 400Mbps signal.

    My concern is, your input signal might be something else rather than a  required continuous mode, 400Mbps signal, in PRBS 7 or 31, encoded in NRZ.

    In general, if your input signal is a pulsed signal, ADN2812 would easily see LOL toggles, and no lock to the input signal.

    Please confirm what input signal you applied to the ADN2812.

    Best Regards,

    Dongfeng

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