Design And Implementation Of Rows Control Circuit For High Speed Ghost Phenomenon Elimination On LED Display Screen

With the increasing demand for LED display quality and cost performance in the industry,the gray level,pixel density,refresh frequency and scanning mode of LED display are constantly improving.Under the condition of high refresh frequency and high scanning mode,the problems caused by parasitic inductance,parasitic capacitance and LED reverse leakage are exposed in use,which become one of the bottlenecks to be solved for high quality LED display screen.In traditional control methods,when the refresh frequency is high or the scanning mode is high,there will be serious drag phenomenon,and when the traditional blanking circuit is used,there will be caterpillar phenomenon after LED aging.At present,there are circuits that can solve the above problems,but there are defects,such as:it will greatly reduce the life of LED or bring greater limitations to the frequency increase.In this paper,based on the study of the drag phenomenon and caterpillar phenomenon of LED display and the traditional solutions,a rows control circuit for high speed ghost phenomenon elimination on LED display screen is designed and implemented based on the0.18?m technology of SMIC.The research work of this paper is as follows:firstly,the architecture design of the whole circuit system is carried out,then the function simulation and optimization of each unit of the circuit are carried out with Cadence series tools,and the function simulation and optimization of the whole circuit are further carried out.Finally,the layout design,drawing,verification and post simulation are carried out,and finally a rows control circuit for high speed ghost phenomenon elimination is produced.In order to achieve the design goal of high-speed elimination and adapt to various common V_F values,before the first sweep of this circuit,the port voltage is pulled up to the elimination voltage corresponding to the selected mode,After the row change,a part of the parasitic capacitance charge can be discharged through the grounding pull-down network for a short time and at a high speed.After the discharge,the port voltage continues to pull down or pull up to four optional elimination voltage values:3.15V,3.3V,3.45V,3.55V.The whole process does not exceed 2?s and the terminal elimination voltage can be maintained stably.The working voltage of the circuit is 5V and the rated current is 3A.The simulation results and test results meet the functional requirements and the performance meets the design requirements.The core problem of this paper is to achieve fast pull-down and pull-up,and to generate a stable and accurate elimination voltage which is consistent with the temperature drift coefficient of LED.The successful streamer of this circuit has achieved the design goal.It can be applied to the LED display screen with common V_F value on the market,which can significantly eliminate the influence of non ideal effect and solve the problem of life and frequency limitation.