Pixel Circuit With Parallel Driving Scheme for Compensating Luminance Variation Based on a-IGZO TFT for AMOLED Displays

This work proposes a new pixel structure based on amorphous indium-gallium-zinc-oxide thin-film transistors (a-IGZO TFTs) and a parallel addressing scheme for high-resolution active-matrix organic light-emitting diode (AMOLED) displays. The proposed circuit compensates for the nonuniformity of luminance that is caused by shifts in the threshold voltage (<inline-formula><tex-math notation="LaTeX">${{V}}_{{\rm{TH}}}$</tex-math></inline-formula>) and mobility of driving TFTs. Measurement results verify that the parallel addressing scheme successfully extends the compensation time and accurately detects the <inline-formula><tex-math notation="LaTeX">${{V}}_{{\rm{TH}}}$</tex-math> </inline-formula> of the driving TFT. Moreover, the proposed circuit reduces the variations of OLED luminance from more than 83% to less than 13% when the <inline-formula><tex-math notation="LaTeX">${{V}}_{{\rm{TH}}}$ </tex-math></inline-formula> and mobility of driving TFT shifts by 1 V and 30%, respectively, and the <inline-formula><tex-math notation="LaTeX">${{V}}_{{\rm{TH}}}$</tex-math></inline-formula> of OLED varies from 0 to 0.9 V.