Why do fpga's have to be so big to be fast

[jackson13]

As the subject says its so odd to me that fpgas have to be big to be fast. I understand that the more logic blocks the more cores you can put on the fpga and make it faster (usually) but still It just makes me mad that a company can't make a fast and small (pin size and physical size) fpga. I believe that fpgas will take over the ASIC market because of their cheapness and modularity so I've been doing alot of research hoping to make a simple ip core and a fpga board that modules can be stacked onto (kind like to PC/104 standard but it will be smaller allowing it to be in products like tablets and phones). I did find the achronix fpga family which is blazing fast in speed but it's got so many pins.

Thank you

[OSwhatever]

As the subject says its so odd to me that fpgas have to be big to be fast. I understand that the more logic blocks the more cores you can put on the fpga and make it faster (usually) but still It just makes me mad that a company can't make a fast and small (pin size and physical size) fpga. I believe that fpgas will take over the ASIC market because of their cheapness and modularity so I've been doing alot of research hoping to make a simple ip core and a fpga board that modules can be stacked onto (kind like to PC/104 standard but it will be smaller allowing it to be in products like tablets and phones). I did find the achronix fpga family which is blazing fast in speed but it's got so many pins.

Thank you

I've seen small BGA FPGAs that can be soldered onto PCB, however this was kind of low gate count FPGA. Large FPGAs are known for consuming much more energy than ASICs and therefore their packaging is usually designed to dissipate as much heat as possible. A mounted fan is not uncommon either.

FPGA are usually better when energy consumption is not problem and when the amount of units is relatively low. Are you going to sell in high volumes, then ASICs are usually cheaper. ASICs SoCs usually have a fair amount of pins too.

ASICs aren't going to be competed out anytime soon and there is a stable market for both FPGAs and ASICs.

[jackson13]

FPGA are usually better when energy consumption is not problem and when the amount of units is relatively low. Are you going to sell in high volumes, then ASICs are usually cheaper. ASICs SoCs usually have a fair amount of pins too.

ASICs aren't going to be competed out anytime soon and there is a stable market for both FPGAs and ASICs.

True and I agree for now but I meant years down the road when they become more efficient. Anyways I'm building the board prototype now and unless it becomes popular I'll won't have many.

I've seen small BGA FPGAs that can be soldered onto PCB, however this was kind of low gate count FPGA. Large FPGAs are known for consuming much more energy than ASICs and therefore their packaging is usually designed to dissipate as much heat as possible. A mounted fan is not uncommon either.

I know there is smaller fpgas but the main problem for me is the speed because the smaller ones are only about 60MHz and the fastest for the pin count in my opinion is the spartan 6 which only runs at 500 MHz.

To further go on about what I would like is an fpga, smaller pin count, and fast speed and though I've never heard of one being small and this speed I would like one to be +1GHz. Let me know if you know one to meet these requirements.

Thanks

[Owen]

To put it bluntly, people who need speed generally also need pins.

Also, fast FPGAs are almost certainly larger (in terms of silicon area). Larger silicon -> requires larger package. If you're in a larger package anyway, I/O comes for free

(and I'm unsure why you've signed up for an OS development forum to discuss FPGAs...)

[jackson13]

To put it bluntly, people who need speed generally also need pins.

Not true at all.

• Examples: phone, tablet, mobile devices

Also, fast FPGAs are almost certainly larger (in terms of silicon area). Larger silicon -> requires larger package. If you're in a larger package anyway, I/O comes for free

Again phones, tablets, mobile devices

(and I'm unsure why you've signed up for an OS development forum to discuss FPGAs...)

I hate when people say this because it's General Rambling you can talk about anything and to answer your question I posted it because I think that its always nice to hear it from somebody that's not in hardware completely because you get a less biased opinion for example if I were asking about the atmel microcontroller vs. the pic in performance if I went to one hardware forum most of them would be biased towards one or the other.

[Combuster]

Examples: phone, tablet, mobile devices

Count the pins to fit an LCD screen, capacitive touchscreen, flash storage (2x), audio in (2x), audio out (2x), GSM, wifi, bluetooth, USB, battery monitoring, camera (2x), keyboards, case sensors...


Also, FPGAs are not a replacement for a general purpose processor. An FPGA can do all the things at the same time, whereas a general purpose processor can only do one thing at a time. Computations that need 1GHz of general purpose computing might only need 10MHz on an FPGA or ASIC because of their parallelism. It's therefore little more than an educative thing to add an CPU core as key component onto an FPGA, because it's much more efficient in terms of money, speed and energy to buy a dedicated ARM SoC instead (and provide the more odd components as an ASIC at the other end of the bus), than to reproduce that setup on an FPGA.

because you get a less biased opinion

We're very biased to expect people coming here for the wrong reasons - because many do.

[Nable]

> phone, tablet, mobile devices
I think that these devices don't use programmable logic elements. Such devices are developed for a long time and they are produced by thousands, so it's cheaper to develop and order non-programmable chips.

[jackson13]

Examples: phone, tablet, mobile devices

Count the pins to fit an LCD screen, capacitive touchscreen, flash storage (2x), audio in (2x), audio out (2x), GSM, wifi, bluetooth, USB, battery monitoring, camera (2x), keyboards, case sensors...

Yes, your right, my bad.

Also, FPGAs are not a replacement for a general purpose processor.

Well it is for now since in my first post I said that I was developing my own computer architecture

An FPGA can do all the things at the same time, whereas a general purpose processor can only do one thing at a time. Computations that need 1GHz of general purpose computing might only need 10MHz on an FPGA or ASIC because of their parallelism

Well a spartan 6 with 190 user I/O running at 500MHz and a 256 would be slower that a pentium 3 running at 1GHz with 128 user pins (64 for data and 64 for addresses) because 1*128=128 and .5*190=95 so the spartan 6 would be a good bit slower but faster that a pentium 111 running at 500MHz, right? Or is there even a way to calculate this because if there is that man, think about a 2000 pins so about 1500 of them are user I/O that runs at 1GHZ if my formula is correct that would mean it is roughly 12 times faster that the pentium III?

We're very biased to expect people coming here for the wrong reasons - because many do.

Okay, I'm sorry for coming to this forum but I that General Purpose was for anything but, I guess I'm wrong so again my apologies.

> phone, tablet, mobile devices
I think that these devices don't use programmable logic elements. Such devices are developed for a long time and they are produced by thousands, so it's cheaper to develop and order non-programmable chips.

Yes your right but it would be cool if I could produce a project that could be cheap enough which is highly unlikely but I was try to say that I would like my pcb size to be smaller to allow more opportunities and flexibility for its purpose(s).

[Combuster]

An FPGA can do all the things at the same time, whereas a general purpose processor can only do one thing at a time. Computations that need 1GHz of general purpose computing might only need 10MHz on an FPGA or ASIC because of their parallelism

Well a spartan 6 with 190 user I/O running at 500MHz and a 256 would be slower that a pentium 3 running at 1GHz with 128 user pins (64 for data and 64 for addresses) because 1*128=128 and .5*190=95 so the spartan 6 would be a good bit slower but faster that a pentium 111 running at 500MHz, right? Or is there even a way to calculate this because if there is that man, think about a 2000 pins so about 1500 of them are user I/O that runs at 1GHZ if my formula is correct that would mean it is roughly 12 times faster that the pentium III?

Nonononono.

A pentium 3 can at best do a single operation on 256 bits of input data in a single clock cycle. An FPGA can do a single operation on all registers in the entire chip. That's at least a factor thousand.

[jackson13]

So a achronix fpga http://www.achronix.com/ would be a 1000 times faster. What about a spartan 6 because I think I'm going to use it.

[sounds]

You should definitely go with the Spartan over the Achronix. Look at Altera's FPGAs but skip Achronix.

Some cell phones do actually include an FPGA. The purpose is to shrink the board layout without creating a custom ASIC just for that line of phone. Of course, that opens up lots of possibilities if the phone is hackable but so far no Android phones have included an FPGA.

In Apple's case, they just create a custom ASIC.