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Imagine I want to design an ASIP for, say, some automotive application. The ASIP is developed and tested using FPGA board.

Is it possible to take the FPGA and put it into the car (without creating the chip in silicon) ?

What would be the problems? Size? Speed? Reliability? Something else?

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You can get automotive-qualified FPGAs. There should be no issues so long as you get one that will work over the temperature range you need and you design the support circuitry correctly. An ASIP may be faster if you build it in silicon, but if the FPGA implementation is fast enough, it's not like it's going to suddenly get slower when you put it in the car. The main 'con' is probably going to be price, but if you're only making a handful then it might be far more reasonable than going full custom.

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  • \$\begingroup\$ Thanks. Regarding the speed: By how much (approximately) does the speed of an FPGA-based ASIP differ from full custom ASIP? \$\endgroup\$ – Dmitrii Pisarenko Nov 20 '14 at 17:45
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    \$\begingroup\$ I'm not really sure exactly. It depends a lot on how much time you put in to tuning the design. However, I do know that FPGAs can usually only run up to a few hundred MHz, while full custom CPUs in silicon can run up to a GHz or more. So if we call the FPGA 500 MHz and the full custom CPU 2 GHz, then that's a factor of 4. But those are probably rather 'best case' numbers. Spartan 6 series parts can really only comfortably run up to around 250 MHz, but other (far more expensive) FPGAs might be able to go a lot faster. And 2 GHz chips will require a lot of engineering to get to that speed. \$\endgroup\$ – alex.forencich Nov 20 '14 at 17:50
  • \$\begingroup\$ FPGAs can also run up to GHzs, but that no fun.. Modern FPGAs are equipped with special macros like DSP blocks and BlockRAM, these components are highly optimized and won't be much faster in an ASIC. On the other side LUTs, registers and especially wires (routing resources) can be implemented in a much smaller way -> shorter, faster, less power consumption, less area, no config bits in between and no path transistors. So if your design uses masses of BlockRAM and DSPs the benefit is low. Even LUT and wire heavy design won't have a benefit factor over 1 -> it's becoming faster but it's no magic \$\endgroup\$ – Paebbels Nov 21 '14 at 21:31

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