Design and Implementation of Readout Circuit with Threshold Voltage Compensation on Glass Substrate for Touch Panel Applications

Abstract

A new on-panel readout circuit with threshold voltage compensation for capacitive sensor in low temperature polycrystalline silicon (poly-Si) thin-film transistor (LTPS-TFT) process has been proposed. In order to compensate the threshold voltage variation from LTPS process variation, the proposed readout circuit applies a novel compensation approach with switch capacitor technique. In addition, a 4-bit analog-to-digital converter ( ADC) is added to identify different sensed capacitor values and further enhances the overall resolution of touch panel. (c) 2011 The Japan Society of Applied Physics