[sdiy] FPAA for analog synthesis?

[Eric Brombaugh]

On 03/02/2010 04:54 PM, Dave Manley wrote:
> All the original SSM/CEM chips are based on an analog array - it isn't a
> *programmable* array - you need to make a mask, and connect elements in
> the array with metal. That said, the number of unique elements in the
> array is small.
>
> If you'd like to see similar technology, including libraries, look
> around here:
>
> http://www.arraydesign.com/
>
> Ok, so what? If there was a big enough market for these parts I'd hazard
> to guess it shouldn't really be all that difficult to design an analog
> array with technology similar or better than the ancient CEM arrays that
> has a modern programmable interconnect. After all, these old devices
> used only a single mask layer, so the routing possibilities aren't
> endless. The question is who is going to pay to develop such a
> technology given the state of ADC/DAC/DSP technology?

Great point.

I would imagine that a big part of the problem in going from a 
mask-customizable analog array to a field-programmable one is that the 
routing resources (switches, buffers, etc) behave much differently than 
pure metal runs.

When Doug Curtis sat down to design a fantastic CEM circuit, he was able 
to make a few simplifying assumptions about the impedance of the 
interconnect. The task gets orders of magnitude harder when there are 
pass transistors & long-line buffers in the mix.

Eric