New Pixel Circuit with Negative Feedback Scheme for AMOLED Smartwatch Displays

This paper proposes a new p-type LTPS TFT pixel circuit for use in AMOLED smartwatch applications with a frame rate of 15 Hz. By adopting the negative feedback scheme, the voltage distortion at the gate node of the driving TFT is greatly ameliorated. The HSPICE simulation demonstrates that the relative current error rates caused by +/- 0.5 V V-TH variations of TFTs are all suppressed below 4.8%. Moreover, the distortions of OLED currents during the long emission period of 66.67 ms are only 2.58 nA at the low gray level when the pixel circuit is operated at a frame rate of 15 Hz.