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  1. #1
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    Why NOT gates not used by designers

    hi all,

    i came across a question,

    WHY 'NOT' GATES WHERE NOT USED BY GOOD DESIGNERS?
    is there any specific reason for not using NOT gates in the designs.

    regards
    sathish

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  2. #2
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    Re: Why NOT gates not used by designers

    Sathish,
    Not gates (inverters) are routinely used in discrete logic design. Often the use of Nand or Nor gates precludes the need.
    Regards,
    Kral



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    Why NOT gates not used by designers

    Yeah

    I agree, besides it is a waste of space to include a integrated circuit of NOT gates and it makes complex the design of the PCB.

    Sal



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    Re: Why NOT gates not used by designers

    It is misconception that designer is not using the inverter .
    Even I can say that only inverter is used by the designers to make a good circuit.
    See the research in the field of vlsi it is only based on inverter .



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    Re: Why NOT gates not used by designers

    Not gates also used in some applications..but not an entire chip can be made using not gates..for ex if we are designing a counter to get clock' we use inveter...but main thing is we can design any gate using NAND and NOR gates..ofcourse these r also making use of functionality of not gate...



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    Why NOT gates not used by designers

    i agree all the above ideas, but i would like to add that the ordinary not gate has propagation delay of 22ns which is very large as compared with nand or and gates which are of 12 ns of maximum . u can check the specifications of the 7404 and any other component at www.alldatasheet.com
    i hope this can help u ....



  7. #7
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    Re: Why NOT gates not used by designers

    Hey Sathish
    Well not gates make the most fundamental circuit of any logic family in the sense that all others are derived from it.
    The reason for not using not gates is that often designers prefer using the entire design using only one type of universal gate say a nand or nor (this sounds intutively appealing too as why would i waste an entire IC of not gate when Iam anyway going to use a nand gate IC)

    @ mr_anderson
    In my understanding not gate should have smallest propogation delay.
    Did you make sure that the components you used for your study belonged to the same family and manufacturer?

    Regards
    tronix



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  8. #8
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    Re: Why NOT gates not used by designers

    Quote Originally Posted by Sathish
    hi all,

    i came across a question,

    WHY 'NOT' GATES WHERE NOT USED BY GOOD DESIGNERS?
    is there any specific reason for not using NOT gates in the designs.

    regards
    sathish
    NOt gates are used by good designers when they are required absolutely..

    Generally,Q and Q_bar are avalable, so inverter is not required.

    placing inverter also depnds on the optimisation os the hardware...



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