Adrian, I am trying to avoid a complex S&H.
Found this: http://memo.cgu.edu.tw/wu-shiung/course/CommunIC/9__Sample_and_Hold_4_24.pdf
My idea: 2 equivalent S&H circuits with just a BS170 and a capacitor like shown at page 9 ("Fully different sampling") looks very simple. The difference is that each FET has to be separately switched: second FET a short time dt after the first FET.
I could give some microseconds settling time before picking the up the voltages by AVR's ADC, and then get a pretty good differential voltage measurement result, I think. Because both S&H are the same the combined errors are widely eliminated.
↧
