| 摘要 |
<p>The invention relates to a device for measuring a variation (DeltaCX) in a capacitance (Cx), comprising: means for charging the capacitance (Cx) from a supply voltage (Vcc), means for discharging the capacitance (Cx) into a reference capacitance (Cs) in a fixed number of discharges (x), and means for measuring a voltage (Vs) and detecting a threshold voltage (VTH) at the terminals of the reference capacitance (Cs). According to the invention, the measuring device further comprises: means for charging the reference capacitance (Cs) with current (Ic) from the supply voltage (Vcc) for a period of time (t), after transferring charge from the capacitance (Cx) into the reference capacitance (Cs), and means for measuring the variation between the period of time (t) relative to a previously measured period of time in order to estimate the variation (DeltaCX) in the capacitance (Cx).</p> |
