difference among fpga and asic

[ash]

What is the difference among asic and fpga? I'm newbie in cpld design.

Best regards.

 

[sawaak]

Hi,
after design, an ASIC requires final metallization step in the foundry whereas FPGA does not, u simply design the FPGA and use it, simple ! .
In most cases the FPGA can be reprogrammed or reconfigured whereas an ASIC does not.

thanks
sawaak

 

[Fom]

ASIC - application specific integrated circuit - has very wide definition. If somebody is talking with you about ASIC you must ask him about definition first. Otherwise you may be confused. Sawaak mentioned about one of the possible way to design and manufacture ASIC device - using Gate Array approach. Another way - Standard Cell approach - will give you a smaller chip size, but you have to buy full mask set, not only metallization masks. Third way - full custom layout - will provide the smallest chip size and best performance but designing device using this way will take much more time and money.

 

[ramesh]

After the design and software verification, the ASIC development requires Foundry to fabricate. It is really costly affair unless the quantity required is very large and the design is proven and no more design changes are entertained.

For small quantity requirements FPGA based designs are much cheaper than the ASIC. In addition the last minute changes can be incorporated in the FPGAs without paying anything extra (since they are S-RAM or Flash based and are reprogrammable). Fabrication is just programming the device at users' site ( Hence FPGAs are called Field programmble Gate Arrays).

ASICs support digital as well as mixed design (Analog and Digital) whereas FPGAs support only Digital design.