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LDC part and jitter of an external clock

MIKHAIL SALOV
Expert 6920 points
Other Parts Discussed in Thread: LDC1612

Good day colleagues,

Could you tell me, how the jitter affects the ENOB of measurements? What frequency tolerance and jitter are needed to reach maximum ENOB (22 bits for the LDC1612)?

Thank you, Mike

  • 0
    TI__Genius 14270 points
    Hello Mikhail,

    The answer is a bit complicated. There are two factors - the edge to edge jitter, which is the difference in time between one edge and the next, but assuming the actual average frequency is constant. The LDC161x measurement is not greatly impacted by this type of clock non-ideality.

    However, the LDC161x IS affected by 'wander', which is the shift in frequency from one moment to the next. You want to minimize this error source. In general, good tempco crystal oscillators will not have a large wander and represent a good approach. The frequency tolerance is not going to affect your ENOB, rather it will appear as a gain error.

    Also, the effective resolution of the LDC161x can be much higher than 22bits - in fact the 28bits of resolution is a cap!

    Regards,

    ChrisO
  • 0 in reply to Chris Oberhauser66
    TI__Expert 6920 points

    Thank you, Chris,

    Got it. Very useful, thank you!

    Could you tell me, how to achieve max enob (maybe higher than 22bits)? What customer should do for that?

    Thank you, Mike

  • 0 in reply to MIKHAIL SALOV
    TI__Genius 14270 points
    Hi Mikhail,

    We will have an app-note published next month which provides details on that.

    Regards,

    ChrisO