Patent ID: 10565420

Abstract:
A capacitive sensing circuit (10) includes a sample-and-hold circuit (SH) coupled to the contact capacitor (Cf); an integrating circuit (100) coupled to the sample-and-hold circuit (SH); a comparator (comp) coupled to the integrating circuit (100); a counter (cntr) coupled to a comparison output terminal and configured to accumulate a cumulative number (Nout) of transitions of the comparator (comp); a voltage boost circuit (104) coupled to the integrating circuit (100) and configured to add a specific value (Vk) to an integrating output voltage (Vout) when the comparator (comp) performs a transition; and a logic circuit (102) coupled to the counter (cntr), where the logic circuit (102) outputs an integration time (Tout) of the integrating circuit (100) when the cumulative number is equal to a predetermined number (Nth), and the integration time (Tout) correlates with a capacitance value of the contact capacitor (Cf).