Amorphous silicon TFT circuit integration for OLED displays on glass and plastic

TitleAmorphous silicon TFT circuit integration for OLED displays on glass and plastic
Publication TypeConference Paper
Year of Publication2003
AuthorsNathan, A., K. Sakariya, A. Kumar, P. Servati, K. S. Karim, D. Striakhilev, and A. Sazonov
Conference NameCustom Integrated Circuits Conference, 2003. Proceedings of the IEEE 2003
Pagination215 - 222
Date Publishedsep.
Keywordsactive matrix organic light emitting diode displays, active pixel area, amorphous silicon TFT, current-programmed drive circuits, device characteristics shift compensation, driver circuits, elemental semiconductors, gate de-multiplexer, glass OLED displays, high aperture ratio pixels, LED displays, on-panel gate drivers, organic light emitting diodes, pixel architectures, plastic OLED displays, programmable circuits, programmable current mirror, Si:H, silicon, TFT circuit integration, TFT threshold voltage, thin film transistor drive circuits, thin film transistors, vertically integrated pixels, voltage-programmed drive circuits

This paper reviews design considerations along with measurement results pertinent to amorphous silicon (a-Si:H) thin film transistor (TFT) drive circuits for active matrix organic light emitting diode (AMOLED) displays. We describe both pixel architectures and TFT circuit topologies that are amenable for vertically integrated, high aperture ratio pixels. Here, the OLED layer is integrated directly above the TFT circuit layer, to provide an active pixel area that is at least 90% of the total pixel area with an aperture ratio that remains virtually independent of scaling. Both voltage-programmed and current-programmed drive circuits are considered. The latter provides compensation for shifts in device characteristics due to metastable shifts in the threshold voltage of the TFT. Integration of on-panel gate drivers is also discussed where we present the architecture of an a-Si:H based gate de-multiplexer that is threshold voltage shift invariant. In addition, a programmable current mirror with good linearity and stability is presented. Programmable current sources are an essential requirement in the design of source driver output stages.


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