Highly reliable a-Si TFTs gate driver with voltage control function according to threshold voltage shift and temperature change

We proposed novel amorphous Si thin film transistor (a-Si TFT) gate driver and driving method useful in improving reliability and narrowing bezel area. The gate driver consists of dual pull-down shift registers and adaptive voltage control circuit. The proposed dual pull-down shift register with just nine transistors in each stage is a revised form of a general dual pull-down shift register for a narrow bezel. The adaptive voltage control circuit periodically measures threshold voltage shift (ΔV_TH) of pull-down transistor and operating temperature; and controls the applied voltage to pull-down transistor according to the measured data to minimize ΔV_TH due to bias and temperature stress. We designed and fabricated the proposed the gate driver. We measured the output of the gate driver and simulated the effect of the adaptive voltage control on ΔV_TH of pull-down transistor. The proposed circuit was more effective in reducing ΔV_TH of pull-down transistor and the bezel area than is the conventional gate driver.