A gate driver circuit with the two-stage pre-charge structure for in-cell touch panels

Abstract

Due to the charge leakage during the touch sensing period and the threshold voltage shift of the driving thin-film transistors (TFTs), the conventional gate driver circuits suffer from poor stability for in-cell touch displays with an increased touch reporting rate. This paper shows a new gate driver circuit, consisting of a two-stage pre-charge structure, which can reduce the charge leakage during the touch sensing period and suppress the threshold voltage shift of the driving TFTs. Simulation results demonstrate that, the rising and falling time differences between adjacent stages are 9.3% and 1.6% for the conventional and the proposed gate driver circuit, respectively. In the case that the threshold voltage of key TFT shifts by +10 V, the rising and falling time degradation ratios are 120% and 2.4% for the conventional and the proposed gate driver circuit, respectively. Therefore, the proposed gate driver circuit is stable for in-cell touch panels with a high touch reporting rate.