12‐3: Current Sensing Self‐Compensation System for Gate Driving Circuit Employing Oxide TFTs

In order to suppress the malfunction caused by the negative Vth of oxide TFTs the shift register consists of double gate TFTs to control the Vth by adjusting top gate bias. The proposed circuit can detect the current consumption of the shift register so that we can hold the current consumption of the shift-register with accordance with the desired current consumptions in the shift-register. The system includes the compensation algorithm which can search an optimized top gate bias in the various circumstances, such as the process fluctuation and ambient temperature. The proposed system provided more stable operation than conventional one at high temperature. Experimental results showed that an output voltage of the shift-register was deteriorated at 80 °C and power consumption doubled during 6 hours at 60 °C in the conventional system. On the other hand, the proposed system can provide the stable gate output up to 100 °C and kept the initial power consumption by adjusting the top gate bias.