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  1. #1
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    how generate prbs in hspice?

    hi
    how i can have "prbs" in hspice....but no use a lfsr beacuse it does not work!!
    can you help me?!
    hurry up :)

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  2. #2
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    Re: how generate prbs in hspice?

    but no use a lfsr beacuse it does not work
    Sure? What did you try yet?



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    Re: how generate prbs in hspice?

    Your implemantation of a LFSR may have failed, but I
    am pretty sure that this does not prove it's not viable.

    A pwlfile type source can be populated (its state file)
    with any series of time/value pairs you like.

    A series string of vpulse voltage sources with varying
    delays / PWs can emulate a random bit stream.



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    Re: how generate prbs in hspice?

    if we can produce a random bit generator in hspice?
    please write a code :)



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    Re: how generate prbs in hspice?

    pwlfile is probably unhandy for long prbs sequences. Thus a behavioral model of the lfsr feedback circuit may be preferable.

    Personally I don't use HSPICE and can't help with an example. I clearly imagine a solution in Pspice or Ltspice, I'm rather sure it exists in HSPICE as well.



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  6. #6
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    Re: how generate prbs in hspice?

    A question is, just how "random" does this bit stream
    need to be? If all you are looking for is a NRZ pattern
    that exercises maximum and minimum transition
    density, for example, that might be easiest built with
    the stack of pulse sources (or, parallel rack of pulsed
    currents, terminated by a burden resistor) that make
    a few different patterns within the simulation interval.

    If HSPICE has a tnoise type capability maybe it has a
    noise source that acts in the time domain. Then all you
    might need is a clocked comparator behavioral model
    to clean it and make logic levels.



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