ASICs Vs FPGAs

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samcheetah

Joined: 25 May 2004
Posts: 672
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Location: Pakistan

14 Nov 2004 10:38 ASICs Vs FPGAs

today i read an article at embedded365.com about FPGAs and ASICs. what i understood is that ASIC based design was once rocket science but due to alot of complexities it is dying out. whereas FPGA simplifies alot of the complexities for the designer.

now what do you people say about this. is this true?

actually i have an ASIC course next year. but a teacher told me that maybe they were going to include an FPGA course. so which one should i take.

wadaye

Joined: 18 Jun 2004
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14 Nov 2004 11:58 Re: ASICs Vs FPGAs

samcheetah wrote:

Hi samcheetah,

FPGA Vendors always say that. But because sometimes FPGA's price and speed

can't meet the need, we still need ASIC.

samcheetah

Joined: 25 May 2004
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Location: Pakistan

14 Nov 2004 13:44 Re: ASICs Vs FPGAs

okay how about learning both ASIC and FPGA. would that be a good idea. and would it be easy? i mean is there some relation between ASICs and FPGAs that will make learning one thing easy if i have learnt the other thing

Big Boy

Joined: 20 Jan 2004
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16 Nov 2004 20:05 Re: ASICs Vs FPGAs

If you can design FPGA, with some more knowledge, you can design ASIC. ASIC is simply a custom chip, that is defined by the same HDL languages that defines FPGA. The design process is similar, but where it diverge is when, for FPGA, you have fixed FPGA cells for which the synthesizer and the place&route will map logic too, where in ASIC, *you* decide what to put, and where, inside the chip (well, the CAD program decides it). In ASIC, there's almost no pre-defined places where to put logic cells and connections.

In an FPGA, if you wish to design a complex logic block, this will use multiple cells in an FPGA. The connections between those basic cells will add a lot of delays, thus, reducing maximum frequency of the design. In an ASIC, you can put your whole logic block in one chunk, with very short traces. In ASIC, the traces are also direct between a gate output and another gate input, where in FPGA, a path between two gates is made by connecting multiple lines (via MOS gates). Those transistors connections are one of the main cause of the longer routing delays in FPGA.

FPGA are getting a lot faster and a lot more dense by the days. This is why the manufacturers hype on using FPGA in designs instead of ASIC. However, ASIC are still needed if you need a really dense design, or a very fast chip. ASIC, however, are custom-made, which imply that if an error is found in the chip (design bug), it may take days/weeks before getting a newer design. It is also prefferable to wait a while before creating a new 'fixed' ASIC, to make sure to find the greatest number of bugs before re-designing it. Getting the new ASIC meen de-soldering the old ASIC from the board, and soldering the new ASIC in place, throwing the old ASIC in the bin. In an FPGA, if a bug is found, a fix can be implemented and tested in the FPGA the very same day. Many FPGA those days are SRAM based. Upgrading FPGA only imply downloading the new binary file to the FPGA configurator.

eziggurat

Joined: 15 Feb 2002
Posts: 245
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16 Nov 2004 22:22 Re: ASICs Vs FPGAs

NRE, this is the main reason for the popularity of FPGA and also the speed is reasonable fast for most application. I recall one of my friends working with Xilinx FPGA in Motorola before implementation to ASIC. My previous company was going to implement a design in ASIC because of low power but opted out for a FPGA because of the cost and the low quantities.

juana

Joined: 29 Jun 2004
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16 Nov 2004 23:39 Re: ASICs Vs FPGAs

It's turns out a production scale matter

Jackwang

Joined: 12 Nov 2004
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17 Nov 2004 2:46 ASICs Vs FPGAs

I think that ASIC design process is complex and its design period is longer than FPGA, but FPGA is easy and convenient to design and implement.
I advise that if your system is small-scale, FPGA is not bad to choose.

vale

Joined: 07 Jan 2004
Posts: 112
Helped: 8

17 Nov 2004 3:31 ASICs Vs FPGAs

From a designer's view, ASIC and FPGA have no significant differencies. All my ASIC chips are emulated in FPGA before tapeout. Master the digital logic design, then choice the prefer one according to your application.

samcheetah

Joined: 25 May 2004
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Location: Pakistan

17 Nov 2004 8:08 Re: ASICs Vs FPGAs

so that means FPGAs are better from a learning point of view. its easy to re-program the whole thing like flash based microcontroller. but in the industry you are free to work with any technology you like. if you need to develop something in less time and dont care for the resources then FPGA is a good choice. but for optimization you would go for ASIC but that would increase the complexity of the design because alot of decisions have to be taken by the designer (and not the software).

am i right???

vale

Joined: 07 Jan 2004
Posts: 112
Helped: 8

17 Nov 2004 8:29 Re: ASICs Vs FPGAs

samcheetah wrote:

yeah.

some points to compare:
1. time-to-market: developing on fpga is much faster than asic
2. cost: for small quantity, fpga is much cheaper than asic, but for large quntity, asic will win due to the low price per die
3. risk: fpga almost has no risk, but you will lose a lot of money for only one small mistake of asic
4. perfermance: normally asic is faster than fpga under same clock frequency
5. interface: your fpga design may have many unused pin occupying large pcb area, while asic has the interface on demand.
6. copyright: though current fpgas provide encryption of design, it's beleived that asic is safer.

the design of both are very similiar. design complier for fpga of sysnopsys can synthesis a fpga design using the almost the same scipt file as for asic, making life more easy.

Last edited by vale on 17 Nov 2004 9:52; edited 1 time in total

kang_999

Joined: 19 Oct 2004
Posts: 11

17 Nov 2004 9:38 Re: ASICs Vs FPGAs

ASICs that Low level design so FPGA that the flexible design

eziggurat

Joined: 15 Feb 2002
Posts: 245
Helped: 10

17 Nov 2004 19:13 Re: ASICs Vs FPGAs

SamCheetah,

There are other FPGAs that can only be program once by Quicklogic (QuickRam) and Actel.

samcheetah

Joined: 25 May 2004
Posts: 672
Helped: 31
Location: Pakistan

18 Nov 2004 7:36 Re: ASICs Vs FPGAs

ok eziggurat but you can also get the ones that are re-useable for learning purposes. so FPGAs have an advantage over ASICs from a learning view point

khorram

Joined: 27 Oct 2004
Posts: 244
Helped: 20

18 Nov 2004 10:27 Re: ASICs Vs FPGAs

I think, we should not forget that a ASIC design can operate faster than a FPGA design and we are not able to design any circuits based on FPGA, specially if the speed is important for us. For example, to design a multiplier which generates its result in a specific time, we may be some problems when using FPGA.
The FPGA design is suitable for academic purposes and prototyping.

Regards,
KH
[/tex]

power-twq

Joined: 10 Jun 2005
Posts: 374
Helped: 3

11 Jun 2005 14:07 Re: ASICs Vs FPGAs

though FPGA is more flexiable than asic,

but FPGA's power consumption and performance is always lower than

ASIC. because the routing delay in fpga is very large,

and FPGA's clock source is very limited, In ASIC, clock resource

is almost unlimited.

please study ASIC.

samcheetah wrote:

samcheetah

Joined: 25 May 2004
Posts: 672
Helped: 31
Location: Pakistan

11 Jun 2005 20:50 Re: ASICs Vs FPGAs

wow, i dont even remember asking that question Very Happy

anyway what i have learnt is that there is always a trade off factor in engineering design. with FPGAs you got re-programmability but with it you got some downsides. but as far as the routing delays are concerned, they can be optimized to some level in floor planning design. you can replace your logic block or move your I/O pins a little here and there and you can get rid of some critical paths. although you cant make it completely delay proof but to some extent optimization is possible.

one more factor is that in an FPGA a maximum of 70% (or something like that) of your resources can be used. but thats the main thing in FPGAs. you have the building blocks and you just have to use them by interconnecting them and making look up tables. and there is no way that you will be able to use all 100% of your resources. so i dont think there is any reason to debate over this. you get some things and you loose some things. thats how it works in this world.

mohahdy

Joined: 22 Apr 2005
Posts: 9

14 Jun 2005 14:50 Re: ASICs Vs FPGAs

please don't forget that you can implement Analog circuits on ASIC but you can't do it with FPGA.
I think that is a main advantage for ASIC over FPGA.

samcheetah

Joined: 25 May 2004
Posts: 672
Helped: 31
Location: Pakistan

14 Jun 2005 17:58 Re: ASICs Vs FPGAs

mohahdy wrote:

please don't forget that you can implement Analog circuits on ASIC but you can't do it with FPGA.
I think that is a main advantage for ASIC over FPGA.

isnt that called System On Chip (SoC) ??????????

srik_naidu

Joined: 03 Jun 2005
Posts: 34
Helped: 2

16 Jun 2005 11:21 ASICs Vs FPGAs

hi,
in case of fpga alot area is wasted but in case of asic it is not like that.
fpga is reprogrammable but asic is not.

with regards,
srik.

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Aser

Joined: 01 Jul 2004
Posts: 74
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17 Jun 2005 10:32 Re: ASICs Vs FPGAs

The same transistor set in ASIC provides 10-100 times more calculations per second than FPGA does with the same energy consumption.
Therefore ASICs is forever.
The disadvantage is : you have to spend a million USD and 3-12 months to get some easy ASIC.
This problem seems to be resolved in the future.
Now the First Time Right method is propagated due to the new EDA technologies.
This approach will be expanded to the way that
if you have, say, correct FPGA project, then you will get the similar ASIC
as the additional service.
Like you make now color photo prints,
or PCBs, or BGA solding.

freeinthewind

Joined: 20 Oct 2004
Posts: 108
Helped: 1

23 Jun 2005 4:47 ASICs Vs FPGAs

now FPGA is not used widely because of price. but the trend is the lower and lower price . i think FPGA will suppress the ASIC in the coming time , only if it's price get lower price.