2
\$\begingroup\$

I had a lab in which we programmed and measured some basic filters in an FPAA. On paper, these devices seem to be a cool way to process analog signals, and their performance is spot-on with theoretical equations (Which is an exception when doing labs at university ;-) )

Yet, you don't come across these parts very often, if ever, when you take things apart - neither in professional, nor consumer electronics. Why exactly?

\$\endgroup\$
1
  • \$\begingroup\$ real life projects rarely need such a 'cool' thing, so there is no real use for it. Only useful and cheap things end up being used widely, so unless you have some serious analogue front end happening that cannot be implemented cheaper with discrete components, then sure use a FPAA. I bet some ultra-expensive medical/science equipment has found use for them. \$\endgroup\$
    – KyranF
    Oct 29, 2014 at 21:35

1 Answer 1

5
\$\begingroup\$

Basically the same reason why FPGAs never caught on for general purpose embedded purposes: they are way too expensive because of their flexibility to even be considered for the kind of BOM costs you're targeting.

Just like in FPGAs, FPAAs are large seas of generic analog cells. For any given filter, you not only need to use the specific elements in these cells that you need, but you also need to factor in a whole bunch of CMOS switches to tie them together and memory to keep track of what goes where. Lastly, an FPAA by design is made to be flexible, so it will implement a set number of cells, often much more or at least a couple tens of percents more than you strictly need for a specific application. This means that there is a tremendous amount of overhead in this type of filter/control loop design.

Next, as you may know from signal theory, it's way less die-efficient to implement analog stuff than it is to do digital calculations. This means that implementing a filter inside a specialized microcontroller - e.g. a DSP - is more efficient than implementing it in an analog fashion.

All of this makes FPAAs a technology that is fundamentally less efficient and more expensive than either other, digital, flexible solutions like DSPs, or than purpose-built analog solutions.

Add to that the not-insignificant burden of requiring people to learn a non-procedural programming language that is fairly alien (FPAAs require yet something else than VHDL/Verilog/C) and the quite significant cost of developing and maintaining such an exotic toolchain, and you don't make matters much better, both on the consumer and producer side of the equation.

So slightly depressingly, it mostly boils down to money.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.