Two electronic interfaces performing a differential (or ratiometric) sensor capacitance to voltage conversion are here presented. The output signal is proportional to the measurand variation x. The two read-out circuits differ themselves in their input stage: the first has an input current-to-voltage conversion, while the second one employs an input voltage source. Both of the solutions utilize commercial second generation current conveyors (CCIIs) as active blocks, in particular AD844. Theoretical analysis, simulated and experimental results have shown a good accuracy. Considering a capacitance variation due to the relative distance change, interface sensitivity (S) and resolution (res) values are constant and satisfactory: for the first solution, S = 8.54 V/Î¼m and res = 674 pm (capacitance resolution value is 89.85 fF, that is â79 dB), while, for the second one, S = 8.13 V/Î¼m and res = 814 pm (capacitance resolution value is 108.5 fF, that is â77 dB).
|Titolo:||CCII-based linear ratiometric capacitive sensing by analog read-out circuits|
|Data di pubblicazione:||2018|
|Appare nelle tipologie:||2.1 Contributo in volume (Capitolo o Saggio)|