This paper demonstrates an in-pixel mobility compensation scheme for AMOLED pixel circuits, which requires only one capacitor and one TFT additionally. The proposed scheme converts the mobility variation into the voltage that is subtracted from the gate voltage of a driving TFT to reduce the current error. The proposed structure is applicable to both n-type and p-type TFT pixel circuits and is robust to the process variation of capacitors because the ratio of two capacitors is utilized. SPICE simulations show that, on average, the current error reduction of 50.1%, 34.9%, and 63.3% is achieved for n-type LTPS TFT, p-type LTPS TFT, and n-type oxide TFT pixel circuits, respectively, compared with a normal pixel circuit without mobility compensation.
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