where to use CPLD & where to use FPGA?

Discussion in 'VHDL' started by kulkarku@math.net, Mar 2, 2006.

  1. Guest

    Hi i am new VLSI technology.
    can anybody suggest me the criteria for choosing FPGA/CPLD for design.
    which parameters play imp role in distingwishing them?
    any guidline for that.
    , Mar 2, 2006
    #1
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  2. Matt North Guest

    They way i distinguish between the two is:

    CPLD
    -Instant On
    -Non-volatile
    -Reconfigurable*
    -Fixed Path Delays
    -Low/Medium size.

    FPGA
    -Setup Time
    -Volatile
    -Reconfigurable
    -Good for large designs.

    With these points in mind CPLD is normally good for control applications and
    logic soaking, FPGA is good for complex designs rich in register
    utilisation.



    <> wrote in message
    news:...
    > Hi i am new VLSI technology.
    > can anybody suggest me the criteria for choosing FPGA/CPLD for design.
    > which parameters play imp role in distingwishing them?
    > any guidline for that.
    >
    Matt North, Mar 2, 2006
    #2
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  3. Chris S Guest

    I agree with Matt's list but I'd add.

    CPLD - handles large sum-of-products logic with fewer levels of logic.

    i.e good for very fast decoders and such like.

    Chris
    Chris S, Mar 2, 2006
    #3
  4. Muralidharan Guest

    CPLD can be used in low gate count designs and FPGAs for more complex
    ones. CPLD is mainly for Glue logic small controllers and others that
    does not require much gates. FPGA can be used for complex algorithm
    implementation and we can even implements RAMs. And more over FPGAs are
    available with different cores now-a-days.
    Muralidharan, Mar 2, 2006
    #4
  5. wrote:
    > Hi i am new VLSI technology.
    > can anybody suggest me the criteria for choosing FPGA/CPLD for design.
    > which parameters play imp role in distingwishing them?
    > any guidline for that.
    >

    Most CPLDs have one flipflop per package signal pin.
    So if your design needs more flipflops than there are signal pins in the
    package, it's a done deal: FPGA.
    David R Brooks, Mar 3, 2006
    #5
  6. Hello,

    Matt North schrieb:

    > They way i distinguish between the two is:
    >
    > CPLD
    > -Instant On
    > -Non-volatile


    Also valid for some FPGA famillies.

    > -Reconfigurable*


    ? Same as FPGA ?

    > -Fixed Path Delays
    > -Low/Medium size.


    Also true for small FPGAs *g*

    > FPGA
    > -Setup Time
    > -Volatile


    Only true for some FPGAs

    > -Reconfigurable
    > -Good for large designs.
    >
    > With these points in mind CPLD is normally good for control applications and
    > logic soaking, FPGA is good for complex designs rich in register
    > utilisation.


    Nowadays its hard to distinguish between CPLD and FPGA because naming a
    device CPLD or FPGA is more marketing than anything else.

    Traditional CPLDs have siginifcant less registers and are very limited
    in routing pathes, but provide a good timing for each path. FPGAs
    provide more registers and are totaly flexible in interconnecting logic
    and registers while having longer routing delays [1].

    bye Thomas

    [1] for compareable technology. Don't expect a 0.5um CPLD to reach the
    timing of a Virtex4.
    Thomas Stanka, Mar 3, 2006
    #6
  7. Guest

    Thanks everybody for the help.

    Thomas Stanka wrote:
    > Hello,
    >
    > Matt North schrieb:
    >
    > > They way i distinguish between the two is:
    > >
    > > CPLD
    > > -Instant On
    > > -Non-volatile

    >
    > Also valid for some FPGA famillies.
    >
    > > -Reconfigurable*

    >
    > ? Same as FPGA ?
    >
    > > -Fixed Path Delays
    > > -Low/Medium size.

    >
    > Also true for small FPGAs *g*
    >
    > > FPGA
    > > -Setup Time
    > > -Volatile

    >
    > Only true for some FPGAs
    >
    > > -Reconfigurable
    > > -Good for large designs.
    > >
    > > With these points in mind CPLD is normally good for control applications and
    > > logic soaking, FPGA is good for complex designs rich in register
    > > utilisation.

    >
    > Nowadays its hard to distinguish between CPLD and FPGA because naming a
    > device CPLD or FPGA is more marketing than anything else.
    >
    > Traditional CPLDs have siginifcant less registers and are very limited
    > in routing pathes, but provide a good timing for each path. FPGAs
    > provide more registers and are totaly flexible in interconnecting logic
    > and registers while having longer routing delays [1].
    >
    > bye Thomas
    >
    > [1] for compareable technology. Don't expect a 0.5um CPLD to reach the
    > timing of a Virtex4.
    , Mar 6, 2006
    #7
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