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  1. #1
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    Level Shifters: Trends in Delay and Transition Time

    Hello all,

    I have a question regarding level shifters. Assuming I have a multi voltage level shifter - 2 voltages; a primary voltage (placed at the top and bottom edge of the level shifter) and a secondary voltage (placed at the center of the level shifter), I was wondering how the rise/fall transition and rise/fall delay time depend on these voltages.

    I've been observing some plots and I have observed that generally, the rise/fall timing does not depend on the secondary voltage but the rise/fall timing does appear to decrease as the primary voltage increases (regardless of process and temperature).

    Is this general trend that I'm observing correct and if so can someone explain to me why this is correct?

    Thank you.

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  2. #2
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    Re: Level Shifters: Trends in Delay and Transition Time

    In all probability you apply the higher voltage through one device, and the lesser voltage through a different device. This occurs internally in an op amp which is a common level shifting device. Is that what you are using?
    The output stage has two different transistors which turn on to greater or lesser extent. To apply a higher voltage, one of its output transistors sources current.
    To apply a lower voltage, the other transistor sinks current.

    If one transistor has more conductance than the other, then it creates dissimilar rise/fall times.



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