• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 20 subscribers
  • Views 194 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

[FAQ] How do I Approximate Propagation Delay and Channel to Channel Skew in an Analog Switch/Multiplexer?

SN74AUC1G08: How to achive exact propagation delay?

MCAV
Prodigy 70 points
Other Parts Discussed in Thread: SN74AUC1G08

Tool/software:

Hi,

I need to delay one signal to use in another stage in my circuit. I need exactly 8ns delay between two signal. To achive this purpose I thought that I can be use AND gates with cascade fashion. But in datasheet propagaiton delay varies a lot for even same capacitive load. For example when VCC=2.5V CL=30p in SN74AUC1G08, propagation delay varies between 0.5ns to 2ns.

Is there a way to achive exact propagaiton delay value? 

Best regards.

  • +1
    Guru 316690 points

    Logic gates do not have such precise timing specifications.

    Instead of using multiple gates, consider adding an R-C filter in front of the gate; together with the input capacitance, a resistor alone should be able to get 8 ns.

    In any case, you will get temperature and manufacturing variations, and you will need to calibrate the delay.

  • +1
    TI__Genius 12871 points

    Hi MCAV,

    As Clemens said a logic gate can have a wide variety of prop delays as that is not their intended purpose.

    Using a 2 channel device will ensure the most similar prop delay between the two signals. Something like the SN74AUC2G34. Then add a series resistor to the input of the delayed channel. I don't know the exact number required for that resistor, so likely some iteration testing would need to be done on the setup to configure it close to 8ns.

    Variations in Device capacitance could cause this delay to vary by small amounts. Again this is not something these devices are typically used for, so we don't have a spec requiring device input capacitance.

    Regards,

    Owen