ASIC or FPGA : The Fairer Technology ?

December 21, 2016 10:06 am Published by Leave your thoughts

 
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Dear Readers,

While starting out your career in the electronics field, you all must have been in an interview where you are asked to differentiate between ASIC and FPGA?

You end up pondering deep into concepts to mumble a few points and yet the question keeps playing in your head. So what actually accounts for the major differences between the two leading VLSI techniques, namely ASICs and FPGAs. Let us take a broader opinion.

fpga-asic design flow

We are aware that the Application Specific Integrated Circuits, or ASICs, are specialized chips that perform pre-defined functions along with operating at very high performance levels. Over the years, new technology breakthroughs have led the complexity levels and hence functionality, to increase from around 5,000 gates to over 100 million gates. Phew!!! Quite a fact that is.  On the flip side, once fabricated, it is not possible to reprogram ASIC like an FPGA. This fact makes ASICs much less flexible than FPGAs.  ASICs are dense chips, that tend to out-perform FPGA typically when scalability is the chosen criterion and accounts for higher scalability. Compared to an FPGA, ASICs have higher R&D cost to design, development and implementation. However, though ASICs have higher R&D cost to design, they suit better to manufacturers when volume required is more. ASIC is developed to be fully customized in terms of logic and gates. (Corporate Training @ Xinoe)

On the other hand, Field Programmable Gate Arrays, or FPGAs, as they are popularly called, are specialized chips that are designed to perform very specific tasks in hardware. Any FPGA basically is constituted by piecing together programmable logic. Since the time the first FPGA was invented in 1985, it has revolutionized the way a function can be implemented and executed in hardware. Using FPGA provides many alternatives as it can be reprogrammed by user as per requirements after manufacturing. Hence, the name ‘Field programmable’. Another important aspect of an FPGA is its flexibility. By the term flexibility, it is meant that the ability to rapidly implement logic in an FPGA for a specific issue is easier yet effective. The time-to-market time span is considerably less than designing a similar change in an ASIC. Hereby, the customer feedback can also be used to incorporate changes readily.

fpga-asic implementation

Moving forward to the performance question, the semiconductor industry has shown significant rise in the high-end FPGA manufacturing as it adjusts to the demands of higher speed applications, complex designs and wide density. Also, since the amount of logic that can be implemented with ease in any FPGA is similar to that of a CPU, functionally based upon Moore’s Law. When we give priority to power consumption by the chip, ASICs have highly dense distribution of logic gates on the chip that amortises the high power consumption so that even though per unit it consumes more power, still the power is consumed more efficiently. ASICs can provide high port density, as compared to FPGAs. For lower production volumes it is advisable to go for FPGA as the non-recurring engineering costs are significant in case of ASICs. Also time-to-market concern can be a prime governing factor for some industries.

Also with fresh developments on the horizon for FPGA technology, the new designs come laden with features that weren’t previously seen. Integrated with many digital functionalities and easy reprogrammable capability, FPGAs sure sounds like a better bet. But it all comes down to the requirements of the project undertaken and the related concern fields. A better approach while manufacturing could be that initially FPGAs can be used for developing a prototype version of an ASIC design thereby, re-programming FPGAs as need be until the specifications are finalized. The final ASIC can then be implemented based upon the FPGA design.

Hope this write-up helps all the budding VLSI Design engineers !

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Author:
Harsha Thakur
Technical Content Writer

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