@erik_squires If you use a delta-sigma encoding process, you are converting analog to digital, no?
No- not exactly. You are converting from analog to a pulse train. Very convenient for going digital from there, which is why its used in the digital encoding process. But despite that its still an analog process.
I get that this is hard to understand but when you see how much its affected by layout, the need to squelch oscillations and the like, that's when its obvious that despite the way its used, its actually an analog process. Digital stuff does not oscillate. Analog stuff can.
A lot of people think delta-sigma (also known as Pulse Density Modulation or PDM) is digital though (specifically 1-bit). I invite them to build the circuit; in solving the problems of making it work despite it being the circuit in a known-good diagram, that's when you really get that most circuitry that handles digital signals is actually analog. Put another way, the resulting signals are *treated* as if they are digital. I think some would say I am cutting the hair pretty fine, but that really is the truth of it.
BTW, we've moved beyond proof of concept and our scan speeds are up to 0.5MHz now (target is 3MHz, but we won't be able to do that with our through-hole prototypes due to afore-mentioned layout issues that are prone to oscillation at the higher rates). Its sounding pretty good too.
