A Low Power and IR Drop Compensable AMOLED Pixel Circuit Based on Low-Temperature Poly-Si and Oxide (LTPO) TFTs Hybrid Technology

Abstract

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 $25{\sim }30$ % 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 $\text{V}_{\mathrm{ th}}$ 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.

Keywords

• AMOLED
• display
• LTPO
• always on display
• in-pixel compensation
• IR drop