[sdiy] Can google's free* 180nm OSHW foundry be used for synth parts?

[brianw]

On Aug 6, 2022, at 2:45 PM, Matthew Skala wrote:
> On Sat, 6 Aug 2022, usenet at teply.info wrote:
>> So in total, I'd say it would be a lot of work, probably a few design respins
>> *AND* a bunch of luck to get something out of it that's useful for SDIY
>> purposes besides the obvious digital parts the process has been optimized for.
> 
> Back in the day people used CMOS inverters like inverting op amps because
> it was easier to get six of those in a package than four real op amps.
> Even now people use those circuits for basic oscillators and Wasp filters
> because of trying to recreate old designs.  I'm not sure that we need
> custom chips just to build a bunch of inverters, but it does suggest that
> a process intended for digital CMOS can build at least a few things synth
> nerds would use.

I recall that these CMOS inverter circuits were all used for the distortion curve of the MOS transistors, which are closer to tube distortion curves. I suppose you could avoid distortion by keeping the signal levels very low, but this Google process would already have limited voltage ranges compared to bipolar.


“I suppose it is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail.”
-Abraham Maslow, 1966

There are tons of digital chips being designed these days, which explains why Google is sharing a foundry to facilitate common digital designs. However, if you want to make synth parts, then the path to success is to start with an analog foundry with the appropriate technology, and share that among lots of designers who are budget constrained. The problem is that there might not be enough money in the synth world to pool together for access to an appropriate foundry.


THAT Corporation took advantage of a military foundry on US soil that came up for sale. They're already making VCA, programmable gain, mic preamps, and transistor arrays.

http://www.thatcorp.com/THAT_Semiconductor_Fabrication.shtml

They even make their foundry available, but it's still a matter of a correct match and sufficient funding.

Brian Willoughby