Study On Zinc Oxide TFT Integrated Circuits-based On AMOLED Application

Active matrix organic light emitting diode display (AMOLED) is one kind of newdisplay technologies, known as the next generation of display technology which could replaceliquid crystal technology. Thin film transistor (TFT) technology is the main core anddifficulty of AMOLED technology. The circuits of TFTs, such as gate integrated drivercircuit, ESD circuit, could take the place of application-specific CMOS chip. The TFTcircuits has become a hot spot in the study of both at home and abroad. This paper mainlydiscusses and researches in zinc oxide (ZnO) TFT model curve fitting, ZnO-TFT gateintegrated driver circuit, ESD circuit design and parameter determination.Since there is not the standard simulation model of ZnO-TFT, this paper introduces akind of parameters extraction method of device, according to experimental data. By using theRPI-62level TFT model and extracted parameters, we can profit experimental measuredcurve to meet the demand of subsequent chapters’ simulation. Then according to theZnO-TFT characteristics, we analysis the disadvantages of traditional gate integrated drivercircuits, such as the circuits exist leakage current path, high power consumption, and lowoutput voltage amplitude. We design two kinds of gate integrated driver circuits, singlesequence dc driver and pipeline sequence ac driver integrated circuit. The simulation resultsof the circuits given by HSPICE have met the demand of design objective of4.8inchAMOLED which uses the2T1C pixel circuit, such as the speed of circuit is50kHz, the outputvoltage amplitude is16V and the power consumption is less than3mW. We explain theexisting problems of the single sequence dc driver circuit after taping out, and find out thecauses. Last, this paper analyses the disadvantages of traditional structure of the ESD circuitadopted ZnO TFT and verified by experiment, such as over high leakage current couldinfluence the display. We introduce a kind of new electrostatic discharge (ESD) circuit, andverify the circuit has ESD protected function by experiment.