In this work an active capacitance multiplication principle is illustrated and applied to the sensor area. By this circuit it is possible to obtain high integrated capacitance values and improve the capacitive sensor sensitivity. After the discussion of the basic principle of the proposed circuit, two different technological solutions are illustrated. The first one is obtained by using two very low voltage bipolar operational amplifiers, able to operate with a supply voltage below 1 V. The second one is a fully integrated CMOS circuit working at nominal supply voltages (5 V). Possible applications of this principle includes narrow low pass filters and capacitive based sensors with high sensitivity.
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