A touch sensor readout circuit using switched-capacitor charge pump

Abstract

This paper presents an on-chip touch sensor readout circuit using charge pump based switched-capacitor scheme. For the proposed touch sensor readout circuit, the touch panel capacitance is directly converted into a voltage level by the switched-capacitor charge pump, which does not require additional signal conditioning for detection. The additional circuitry following the charge pump such as the comparator and flip-flop does not consume any static current. Therefore, the suggested touch sensor can lead to a compact and low power on-chip solution with fast detection time. The prototype circuit is fabricated using CMOS 0.35 mu m technology, where the consumption current is only 2.2 mu A.