A Compact Low-Power Shunt Proximity Touch Sensor and Readout for Haptic Function

Abstract

This paper presents a compact and low-power on-chip touch sensor and readout circuit using shunt proximity touch sensor and its design scheme. In the proposed touch sensor readout circuit, the touch panel condition depending on the proximity of the finger is directly converted into the corresponding voltage level without additional signal conditioning procedures. Furthermore, the additional circuitry including the comparator and the flip-flop does not consume any static current, which leads to a low-power design scheme. A new prototype touch sensor readout integrated circuit was fabricated using complementally metal oxide silicon (CMOS) 0.18 μm technology with core area of 0.032 mm² and total current of 125 μA. Our measurement result shows that an actual 10.4 inches capacitive type touch screen panel (TSP) can detect the finger size from 0 to 1.52 mm, sharply.