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DAC43608: Differences of "Glitch" and "Digital feedthrough"

Hideki Hayashi1
Expert 7460 points
Part Number: DAC43608

Hello,team

This question would be general DACs question.

I'm confused at the difference between "glitch" and "digital feedthrough".

As a definition, glitch noise is happened when digital code is changing. And digital feedthrough noise is come from digital input edge or clock edge.

I think these two noises would be occurred at the same time, when clock rises. Is it right?

If it is right, how large noise there are when clock rises?

Is there only Code change glitch impulse (nv-s) (= 4nv-s in this product)? Or Code change glitch impulse (nv-s) + Digital feedthrough (nV-s) (= 24nv-s in this product)?

Regards,

Hayashi

  • 0
    TI__Guru 53453 points

    Hi Hayashi-san,

    My colleague Uttam will get back to you on this.  Both the US and India are on holiday today (Monday), so responses are delayed.

    Thanks,

    Paul

  • 0 in reply to Paul_Frost
    TI__Genius 14220 points

    Hi Hayashi-san,

    Thank you for your query. You're right that the code-to-code glitch is due to the switching of the resistor string while the digital feedthrough is caused by the crosstalk between the digital lines and the outputs.

    Practically, these two components don't appear at the output at the same time: the digital feedthrough appears first and then the glitch appears once the digital frame is over followed by the output slew time.

    In order to calculate the total impact on the output signal, you can add the energy components of glitch and feedthrough. However, the digital feedthrough occurs mainly because of the fast rise times of the digital signals and the board layout. Hence, it can be minimized with simple filtering. The glitch is a more intrinsic parameter for the DAC and it needs special care to minimize this.

    The datasheet specifies these parameters independently.

    However, I would recommend you to consider the digital feedthrough provided in the datasheet as a typical number and it might be smaller or larger on a given board depending on the layout.

    Hope that answers your question.

    Regards,

    Uttam Sahu

    Applications Engineer, Precision DAC

  • 0 in reply to Uttam Sahu
    TI__Expert 7460 points

    Hello Uttam-san,

    Thank you for your explanation.

    I can understand and will tell that to my customer.

    Regards,

    Hayashi