In this paper, an AMOLED pixel circuit based on low-temperature poly-crystalline silicon and oxide (LTPO) thin-film transistors (TFTs) hybrid technology is proposed, which features only two transistors in a serial connection with OLED. The power supply can thus be reduced by 25~30% in the "Always-on-Display" (AOD) mode compared with the earlier LTPO pixel circuits which usually have three transistors in the current path and need a higher supply voltage. Furthermore, in addition to a strong suppressing ability to Vth variations/shift, the proposed pixel circuit has an excellent compensation ability for current-resistance voltage drops (i.e. IR drop), which is also superior to the earlier LTPO ones where the IR drop has to be compensated externally. Therefore, the proposed LTPO pixel circuit is able to provide AMOLED displays with lower power consumption and higher display performance than the earlier ones.

In this paper, high reliable a-IGZO TFT gate driving circuit was designed. Series-connected two-transistor (STT) structure and dual low-voltage-level power signal (Vss) were used to solve the initial negative Vth of IGZO TFTs. Special pull-down holding part was designed for wider Vth shift window during panel operation. The Vth shift margin of this proposed GOA design is from -5V to +9V by using Eldo-Spice simulation system. In addition, the pullup control part could also play a role to pull the Q node voltage down and it is helpful for narrow border design. Finally, a 31-in. 8K4K 287-ppi TFT-LCD was successfully demonstrated based on the study above.

A high reliable amorphous silicon gate driver with shared dual pull-down units is proposed and fabricated for large-sized TFT-LCD applications. A special unit in the driver is designed to generate bipolar pulse bias for low-level holding TFTs to suppress the threshold voltage shift, which achieves 40.5% and 34.8% improvement compared with conventional DC and unipolar pulse bias respectively according to measurement results.Author Keywords gate driver; bipolar pulse bias; shared dual pull-down units. P-12 / Z. Hu • SID 2014 DIGEST

A simple a-Si TFT integrated gate driver on array which can work at low temperature is proposed and studied. The circuit features a capacitor coupling gate bias at the TFT for suppressing feed-through effect. The bias allows the circuit output a well-formed waveform even at low temperature.

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