In one embodiment, an apparatus comprises a plurality of capacitors, each having a first electrode and a second electrode. The apparatus includes charging circuitry coupled to the first electrodes and sensing circuitry coupled to the second electrodes, the sensing circuitry configured to detect changes in capacitance across the capacitors responsive to movement of an input object relative to the apparatus. Interpolating circuitry identifies which one of the capacitors is nearest to the input object according to the detected capacitance changes.