1. Nobody "publicly". It has been done before by industry.
2. 1/f noise mostly electrical/physical issue, not thermal. Difference would be rather marginal.
Thanks everybody for feedback. I have some questions. I also try to clarify my cryptic post.
1. Clear
2. Do you have some numbers. How big is the oven thermal error by analog design. e.g you KX design
3a. SD ADC with unlimited accuracy? Do tell, I'd like to have one.
3b. Your ADC in best case as good as your reference is.
3c/d. It is not easy nor cheap to mitigate wide bandwidth noise.
Modern SD are designed to interface with sensors - not to make voltmeters. Sensing Ube is perfect match for them. Lets put some numbers
- Voltage range - 0...600mV
- glueless interface
- accuracy 10ppm = 6uV.
Assuming Ube has -2mV/C . 6uV= dT accuracy =0.003C=3mC.
Are my calculation correct. If yes, is 0.003C accuracy enough.
Most reasons why hobby players don't bother with digital control/compensation for LTZ1000-based reference is elegance of analog ways. Adding digital complexity over something like LTZ also introduce all the digital issues, noise, charge coupling, PCB layout impacts, additional filtering, more points to generate parasitic thermal EMFs (extra heat from DAC/ADCs), bigger power consumption (bye bye battery operation). And then spending hundreds hours troubleshooting and revising design to overcome heroically all these challenges, and for what end result?
That being said, don't listen too much, and go ahead on trying it. I'm sure it will be fun to learn and something useful can be discovered in the end result
Clear. I realize the enormous job done from industry leaders and comunity. The easy way is to copy exisiting design. Most likely I'll copy , adapted version of your design. WHy
1. At best I can achieve the same performnce as yours. - makes no sense to goes further
2. I can acieve that with 1/10 of efforts. - still a lot of work for shingle person. I'll explain why digital aproach can be achieved 10 times faster.
- easy to quantify influence of external factors. Air flow, te,perature change rate, humidity, air preassure etc.
- Well defined theory, no magics and mysteries
- straightforward approach from transfer function to control loop design
- known theory of multi variable control
- fast iteration loops - change software vs redesign board
- easy debug - easy to quantify the difference - software diff vs components/PCB/ Soldering and other fragile parameters
BR
Miro