Maximum clock frequency ?

Discussion in 'VHDL' started by Skybuck Flying, Aug 2, 2005.

  1. Hi, ;)

    I am beginning to understand how CPU's and chip like that work.

    I think the clock frequency is very important.

    It's almost like the hearbeat of the computer.

    It determines how fast the signals change from zero to one and back.

    And these signals are what drives the computer.

    So I think a very important question would be:

    What is the maximum frequency that these kind of "cpu clocks" can provide ?

    Other components should ofcourse also be able to handle these high

    Like t_flipflops etc :)

    So what's the best of the best at the moment ? ;)

    Skybuck Flying, Aug 2, 2005
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  2. Skybuck Flying

    ALuPin Guest

    Hi Skybuck,

    this is a VHDL discussion board ;o)
    And not a general information board ;o)

    ALuPin, Aug 2, 2005
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  3. Skybuck Flying

    jon Guest

    The fastest transistor I've heard of operates at 604 GHz.

    jon, Aug 2, 2005
  4. Skybuck Flying

    Neo Guest

    I thought the Illinois university guys had obtained transistors
    operating at 1 Tera Hz .
    Neo, Aug 2, 2005
  5. Remember also, that the clock frequency is only one 'part' of the equation
    giving what the system can do. It is effectively multiplied by the 'width'
    of the registers, when dealing with numerical values, and also may be
    multiplied internally using either a PLL, or short phase delays, so
    multiple operations are generated in each clock. you should really think
    about the clock, like the speedlimit on a road, with the width of the
    registers, being perhaps like the difference between a motorbike, and a
    bus, while the internal phase seqencing, acts like having multiple lanes
    of traffic running in parallel. In terms of the actual number of people
    the road can carry, you have to multiply all these differences together,
    but the clocking limits the minimum time a single person can take to
    transit part of the road. An internal PLL, acts like a local 'expressway',
    reducing this time.

    Best Wishes
    Roger Hamlett, Aug 2, 2005
  6. Hello Skybuck,

    forget T-fliflops. This is the least important part of an
    IC-design. I know you read about it in a VHDL intro book,
    but they made this just as an example and not because it's

    You should really look first for a FPGA design flow,
    e.g. , ...,
    After you understand that you can look for full costom ICs.

    You can buy divider flipflops with 20GHz.

    Best regards,
    Helmut Sennewald, Aug 2, 2005
  7. Ok so if this is my clock rate:


    Can the PLL divide it into:

    1111111100000000111111100000000 ? ;)

    or maybe even further into ;)

    11110000111100001111000011110000 ? ;)

    I think that's what it could do/does ?

    So the PLL creates a faster clock rate inside the chip ?

    Would this mean the "normal" clock is outside of the chip ?

    How many real clocks or oscilators(=clock?;)) are there ?

    Can the main memory chips and the cpu share the same clock ?

    However a transistor is not a clock so my original question is not yet
    answered ? ;)

    So what's the fastest clock on todays computers and say 5 years from now ?

    For my one bit streaming cpu a PLL might not be interesting...

    Since I was more thinking of having all the bits stream
    across/through/into/out of the cpu directly from main memory ;)

    The question is if multiple bits can be transfered in serial over a single
    wire with a slower clock frequency and then still be processed by a cpu with
    a faster clock frequency... the cpu would have to buffer some bits I guess.
    Or something like that... maybe not possible ;) or maybe it would be
    possible with bursts.

    However... since I don't like all this complexity... (and I dont like bursts
    too ;)) I am wondering if my simple cpu will need a clock at all ;)

    So just for the kick of it ;)

    Can VHDL also be used to design/test circuitry without clocks in them ? ;)

    Skybuck Flying, Aug 2, 2005
  8. Skybuck Flying

    Tim Wescott Guest

    Instead of asking all these painfully basic questions and getting
    one-off short answers, perhaps you should go shopping at your local
    bookstore or on the web for information on computer architecture?
    Trying to get 50,000 words worth of information from random newsgroup
    queries is like trying to build a house out of cut-off ends of 2x4
    lumber -- and it makes us work at answering questions bit by bit that
    are better answered all at once (or at least in much larger chunks).
    Tim Wescott, Aug 2, 2005
  9. Skybuck Flying

    Mac Guest

    Actually, he is cross-trolling to comp.arch, comp.lang.vhdl, and, which is where I'm reading it.

    Mac, Aug 3, 2005
  10. Skybuck Flying

    Bernd Paysan Guest

    The fastest transistors seem to be carbon nanotubes, and IIRC, they go well
    above 1 THz. The main problem to get real figures is probably the
    unsuitable equipment to measure these things. In theory, a carbon nanotube
    oscillator should be able to drive a 300nm carbon nanotube dipole, emitting
    blue light (now that would be something that's not that hard to measure).
    Bernd Paysan, Aug 5, 2005
  11. Skybuck Flying

    JeffM Guest

    I think the clock frequency is very important.
    In addition, learning to use a search engine
    and finding out how to narrow a search
    has an instructive quality all its own.

    Here's the one for the sci.electronics.* part of the Usenet Archives:
    JeffM, Aug 5, 2005
  12. I am getting a error:

    Server Error
    The server encountered an error and could not complete your request.
    If the problem persists, please report your problem and mention this error
    message and the query that caused it.

    Maybe only a temporarely problem.

    I still haven't seen any answer to my question... ;)

    What's the maximum frequency nowadays ?

    Skybuck Flying, Aug 6, 2005
  13. Skybuck Flying

    Dan Koren Guest

    While one should not in general feed the trolls as a
    matter of principle, I will make an exception just to
    point out that your question suggests you have not
    really thought about the problem in any depth.

    What matters most for real circuit design is not the
    highest frequency that the clock can generate -- but
    rather how far can the clock signal be propagated
    reliably and without excessive distortion (distance
    and fan-out).

    Dan Koren, Aug 6, 2005
  14. Skybuck Flying

    xray Guest

    Is something we are all beginning to wish you would take more seriously.
    xray, Aug 6, 2005

  15. Hello Skybuck,

    you should see a dozen answers to your question if not then
    try another news group reader.

    You can achieve 20GHz(20e9Hz) with a T-fliflop.

    Other insist they can get 100Tflop.
    Now I know why you wanted a design with T(flip)flop.
    Maybe this "flip" doubles the Tflop. :)
    Sorry, I couldn't resist.

    A real answer:

    A simple processor alone could achieve some GHz, e.g. 10GHz,
    but it becomes very expensive and anotrher problem is feeding
    such a beast with enough data from memory.
    This is then something for an IEEE paper, but nothing which
    will make you rich.

    Best regards,
    Helmut Sennewald, Aug 6, 2005
  16. Yesssss but maybe the propagation length doesn't matter for a small circuit
    like my 1 bit cpu =D

    So I would still like to know what the maximum frequency is ;)

    And in case the circuit is bigger how do circuits nowadays propagate the
    clock signal reliably ;)

    Skybuck ;)
    Skybuck Flying, Aug 6, 2005
  17. Skybuck Flying

    Sander Vesik Guest

    Or maybe it does? But its up to you to find out.
    There is no such thing. Or very close to no such thing, except possibly
    somewhere in UV/r?ntgen border area.
    You should first use Google and then ask. Or will you only be sensible when
    skybucks^H^H^H^H^H^H^H^Hpigs fly?
    Sander Vesik, Aug 6, 2005
  18. ??

    But a T-flipflop is not a clock ???
    Skybuck Flying, Aug 6, 2005
  19. Skybuck Flying

    Dan Koren Guest

    For a single bit you can use your great-grandfather's
    pocket watch. It shouldn't make any difference.

    Dan Koren, Aug 6, 2005
  20. Skybuck Flying

    Mike Guest

    .... we're back that 1-bit Turing machine again ...

    Maybe this thread is a real live Turing test? :)
    Mike, Aug 8, 2005
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