A 3-TFT current-programmed pixel circuit for AMOLEDs

Current programmed circuits have demonstrated threshold voltage V/sub TH/ shift compensation to provide a stable drive current to the organic light-emitting diode (OLED). However, the degree of stability of drive current depends critically on the dynamic behavior of the circuit. This paper examines the dynamic behavior of a 3-TFT current programmed pixel and analyzes the impact of V/sub TH/ shift on the OLED drive current. The pixel circuit was implemented in amorphous silicon technology and lifetime tests show a 11% current degradation at 700 h.