[sdiy] New FPAA experiments with Scilab/Modelica

[Lanterman, Aaron D]

Howdy Synth DIYers,

Lately I’ve been experimenting with a toolset for Field Programmable Analog Arrays based on floating gate technology. My colleague Jennifer Hasler and her team have created a toolset based on Scilab/Xcos in an Ubuntu image you can download and run in VirtualBox. It includes simulation capabilities using Modelica, which is embedded Scilab. I’m documenting some of my progress on YouTube.

I put together a playlist here:

https://www.youtube.com/watch?v=4XvQ4LVi0OA&list=PLOunECWxELQTCZEqIbHZpRmIEeQR80o3j

There’s videos on common source and common drain amplifiers, and voltage dividers that use OTAs instead of resistors (which seems very strange to me, coming from a PCB-level design background, but it turns out that transistors are “cheap” on the chip whereas resistors are expensive in terms of real estate and complicated).

Jen likes to run her MOSFETs in the subthreshold regime; most books just call this “off,” but it turns out there’s an exponential dependency of current on V_GS that’s reminiscent of BJTs vs. the square law I’m used to with MOSFETs.

Enjoy!

- Aaron