Voltage Programming Pixel Circuit Design For Compensation Threshold Voltage And Mobility

Display technology has evolved from the past Cathode Ray Tube(CRT)display to the now mature Thin Film Transistor Liquid Crystal Display(TFT-LCD),as well as a new generation of self-illuminating Active-Matrix Organic Light-Emitting Diode(AMOLED)displays.Each pixel unit in the AMOLED display technology is composed of a Thin Film Transistor(TFT),an Organic Light-Emitting Diode(OLED),and a capacitor,and the OLED emits light by the TFT.There are many types of TFTs.Among them,low-temperature polysilicon TFTs have the advantages of high mobility compared with other types of TFTs.Therefore,the ability to drive OLEDs is strong,and has been widely used in high-resolution,medium-and small-sized AMOLED display technologies.In the application process,low-temperature polysilicon TFTs also have some problems,and their electrical characteristics will exhibit non-uniformity,which is caused by the unevenness of the polysilicon film and the electrical stress of the TFT under long-term operation.The non-uniformity of electrical characteristics mainly manifests as changes in threshold voltage andmobility.In order to compensate for these changes,it is necessary to design a suitable pixel circuit.This paper designs a full P-type 6T2 C voltage programming pixel circuit.In the circuit design process,in the compensation phase,the threshold voltage of the driving tube is extracted by driving the source-level discharge of the tube.In the data input phase,adjust the timing of the switching tube,increase the voltage of the source voltage of the driving tube,and realize the compensation of the mobility.The simulation results verify that the current error rate is 10% when the threshold voltage of the drive tube changes by ±0.5 V.When the drive tube mobility changes by ±30%,the current error rate is up to 9%.In addition,this paper also designed an N-P hybrid 5T2 C voltage programming pixel circuit.In the circuit design process,in the compensation phase,the gate is charged by the diode connection of the drive tube,and the threshold voltage of the drive tube is extracted.In the data input phase,the timing of the switching tube is adjusted,and the gate voltage of the driving tube is reduced to compensate for the mobility.The simulation results verify that the current error rate is up to 9% when the threshold voltage of the drive tube changes by ±0.5 V.When the drive tube mobility changes by ±30%,the current error rate is up to 6%.Finally,this paper also designed an all-N 5T2 C voltage programming pixel circuit.In the circuit design process,in thecompensation phase,the threshold voltage of the driving tube is extracted by the drain discharge method in the connection mode of the driving tube diode.In the data input phase,adjust the timing of the switching tube,increase the gate voltage of the driving tube,and realize the compensation of the mobility.The simulation results verify that the current error rate is up to 6% when the threshold voltage of the drive tube changes by ±0.5 V.When the drive tube mobility changes by ±30%,the current error rate is at most 9%.