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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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  • Hi Dongfeng,

    Thanks for your reply.

    1. The signal is normal pattern in NRZ encoding. Not by PRBS7 test pattern.

    2. by AC-coupling.

    3. The signal is continuous type. But there exist some long "1" or long "0" pattern. The longest run is 11.

    Please check "D2" in Fig1. of previous post. The pattern is repeated every "D2" toggle, named as one frame(around 16.7ms). So the LOL is asserted around every 12 frames(around 200ms).

    Is it possible to release the re-lock threshold from 1000ppm to more?

    Thanks a lot.

Reply
  • Hi Dongfeng,

    Thanks for your reply.

    1. The signal is normal pattern in NRZ encoding. Not by PRBS7 test pattern.

    2. by AC-coupling.

    3. The signal is continuous type. But there exist some long "1" or long "0" pattern. The longest run is 11.

    Please check "D2" in Fig1. of previous post. The pattern is repeated every "D2" toggle, named as one frame(around 16.7ms). So the LOL is asserted around every 12 frames(around 200ms).

    Is it possible to release the re-lock threshold from 1000ppm to more?

    Thanks a lot.

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