GOA Circuit Pull-Down Unit Series Transistors Leakage

The pull-down unit is segmented into multiple thin film transistors (first TFT, second TFT, third TFT) with distinct functions: the first TFT controls the bootstrap capacitor discharge, the second TFT regulates the pull-down current, and the third TFT provides additional control. This segmentation allows independent optimization of each transistor's parameters to maintain voltage stability at point Q while managing leakage current effectively.

The patent optimizes critical parameters including the threshold voltages of the thin film transistors, the capacitance value of the bootstrap capacitor, and the dimensional parameters (width and length) of the transistors. By carefully selecting these parameters, the circuit achieves stable voltage at point Q and reduced leakage current without requiring fundamental redesign of the overall GOA circuit architecture.

The bootstrap capacitor serves as an intermediary energy storage element that supplies charge to compensate for leakage current in the pull-down unit. The capacitor is strategically positioned and controlled by the first TFT to provide timely charge replenishment, thereby reducing the impact of leakage current on voltage stability and extending the operational life of the thin film transistors.

The circuit implements implicit feedback through the bootstrap capacitor discharge control mechanism. The first TFT monitors the voltage condition at point Q and automatically adjusts the discharge timing and duration of the bootstrap capacitor, creating a feedback loop that compensates for leakage current and maintains stable operation over extended periods.