Field Programmable Analog Array

[earthtonesaudio]

This was news to me but really fascinating.  The gist of an FPAA is that it is a chip which contains many analog building blocks, with configurable routing between them. 

Similar to an FPGA but not yet anywhere near the same kind of scale as say, a Xilinx Spartan 3.  More like 2-4 configurable analog blocks (CABs).  And where the popular conception of an FPGA is a big homogeneous bag of NAND gates, the CABs in FPAAs tend to be more heterogeneous, with contents ranging from individual transistors, to op-amps, to matrix multiplier circuits.

Found a really good paper about making an incrementally larger FPAA here.  There is at least one company making these for sale today, and their prices seem to be less than $200 USD for a development board.  A bit high compared to an Arduino, but strikingly different.

Anyway, the tech is not exactly new but I've been around the block once and had never caught a glimpse of this sort of thing, thought I'd share.

[SISKO]

Thanks for sharing!

[tommy.genes]

Slightly OT and briefly coming out of hibernation, but I've often wondered if - since digital components are sometimes shoehorned into analog circuits like Anderton's venerable Tube Sound Fuzz - if FPGAs could be re-purposed into analog matrix switches. The FPAA seems like an interesting, alternative approach to that idea. I'd be interested to hear if anyone has any success with those.

Another interesting area is the new class of fixed microcontrollers (usually ARM-based) paired with FPGA-like capabilities in the same chip, like the Cypress PSoC family, the Microsemi SmartFusion2 or the QuickLogic EOS S3.

In fact, I wonder if we could get somebody like Spin Semiconductor or Cool Audio to make just such a chip ideally suited to both DSP and digitally-programmable analog audio effects.

-- T. G. --

[Digital Larry]

I didn't dig too deeply into this but I have a pretty straightforward question or two...

What benefits does this offer over an equivalent DSP implementation?

What are the applications where this really matters?  More to the point, where are these chips being used?

For tone shaping via filtering, I'm not convinced analog is better than DSP.  For time delay based effects, no way.  For making a germanium based fuzz tone, I could be swayed.

[tommy.genes]

I've always found distortions and filters to be not as good in DSP as in analog, especially WRT their touch sensitivity, although the DSP is getting much better.

My main interest in the hybrid MCU/DSP plus FPGA/FPAA fabric chips is to simplify - or even eliminate - the design of the outboard circuitry. You could "program" buffers, gain stages, analog muxes, switches and other functions that would previously have been separate, discrete circuits.

-- T. G. --