Fine-Tunable Emission Pulse Generation Circuit Based on p-Type Low-Temperature Poly-Si Thin-Film Transistors for Active Matrix Organic Light-Emitting Diode Displays

Abstract

Active matrix organic light-emitting diode (AMOLED) displays have deployed the compensation techniques to cope with the luminance non-uniformity issues caused by variations on electrical characteristics of thin-film transistors (TFTs). While some compensation circuits require control signals of longer pulse widths than a line time, the luminance control as well as the higher bit depth representation have been also accomplished by adjusting the pulse widths. A proposed EM pulse generation circuit consists of 11 p-type low-temperature poly-Si (LTPS) TFTs and a one coupling capacitor. While previous tunable circuits could address pulse widths of either even or odd multiples of a line time, the proposed circuit can generate any multiples by changing phases of additional clock signals. In particular, the internal inverter is implemented with a load connected to the output of a previous stage's inverter to reduce the power consumption over pulse widths. The coupling capacitor is also connected between two adjacent stages through one TFT, eliminating coupling noises on the output pulses. The proposed EM circuit is simulated at a line time of 3.8 µs for a 120 Hz 3840 × 2160 display. The results ensure that pulse widths from three to 2160 lines are generated successfully without coupling noises and the small variation on power consumption from 1.23 to 0.33 mW is achieved at 30 stages for the whole range of pulse widths, compared to the large range from 1.26 to 76.91 mW with the inverter of a diodeconnected load.

Review of Integrated Gate Driver Circuits in Active Matrix Thin-Film Transistor Display Panels

“…Therefore, compensation techniques must be implemented in pixel circuits to address these variations [97][98][99][100][101]. The emission pulse generation circuit is a specialized circuit to generate signals that drive the emission TFTs (EM TFTs) of a pixel circuit for controlling the current flows through OLEDs [102][103][104][105][106]. In general, the threshold voltage compensation is achieved by sensing the threshold voltage of a driving TFT based on the diode-connection condition, where EM TFTs cut off the current paths through OLEDs to avoid the undesired light emission and to sense the accurate threshold voltage as presented in Figure 16 [107], where P1 is a driving TFT and P4 and P5 are EM TFTs.…”

Bilateral sidewall engineering Si1–x Ge x iTFET for low power display application *

“…Manufacturing costs and size constraints also present challenges, especially when higher pixel densities and larger display areas are targeted. To address these limitations, several solutions have been proposed, ranging from α-Si, poly-Si, LTPS-Si [17] to oxide semiconductors such as ITO, ZnO, InGaO, IGZO [18][19][20] to overcome the low mobility problem in conventional TFT. While these materials improve I ON migration rates and response speeds, they still require higher operating voltages.…”