We have analyzed two p-Si TFT pixel driving circuit with accurate model parameters using AIM-Spice software.We primarily focus on some aspects what we consider can impose much influence on OLED driving circuit

such as ratio of width and length of driving thin-film transistor

influence of storage capacitance and so on.Because there are many parasitical capacitances in the circuit

it is very important to choice reasonable storage capacitance to eliminate the influence of some disadvantageous factors and maintain the circuit to work.By the simulation results

reasonable T

2

W

/

L

ratios can be obtained.The simulation results also showed that the OLED grayscale could be adjusted by changing the data voltage.The impact of storage capacitor on output characteristic was discussed.The lower size capacitor will reduce the OLED current during the pixel electrode OFF period.And too large capacitor will increase a charge time constant

which impacts on the respond speed and brightness of OLED.The larger T

1

W

/

L

ratios will also result in the drop of the OLED current during the pixel electrode OFF period.So it is necessary to select them carefully.From the transient characteristic of the influences of the scan pulse voltage on output current

it is clear that the lower scan voltage value will result in the OLED current to be not proportional to data voltage.Thus the OLED brightness cannot follow the variation of the data voltage.The reasonable scan voltage value will solve the above problem.Through analysis

we conclude that best circuit parameters and using them can practice gray-scale signal response analysis in order to test its fast switching speed which is regarded as one of OLED best advantages.Conclusively with best circuit parameters above

driving circuit can drive OLED to desire brightness display

maintain driving current in every frame period

quickly respond to time-changing gray-scale signal

and minimum the influence of TFT non-linear character on OLED current to the least degree.All the works can be used for choosing reasonable parameters in the design and analysis of OLED driving circuit.