Establishment And Verification Of Circuit-level Simulation Model For Electrostatic Gun

Electrostatic discharge(ESD)has always been the main concern and prominent threat of electrical and electronic components and products.ESD events occur due to the accumulation of charge on metallic and non-metallic geometric structures,which is usually triboelectric.This direct or indirect interaction of charged objects is the main cause of ESD discharge.The discharge of ESD pulse makes both hard and soft failures of the product possible.Therefore,it is very necessary for electronic products to monitor and protect ESD.The main test standard for system-level ESD testing is the IEC61000-4-2 standard specified by the International Electrotechnical Commission.During the system-level ESD test,we use an ESD generator(electrostatic gun)to simulate ESD discharge scenarios.The discharge current waveform must comply with the IEC61000-4-2 standard.However,the frequent use of electrostatic guns to measure the system-level antistatic level is an expensive and time-consuming process,so it is necessary to develop an effective method to analyze and predict the electrostatic protection capabilities of the equipment.There are three techniques for simulating the output waveform of an electrostatic gun: full-wave simulation,numerical model,and circuit model.Full-wave simulation is very useful,it provides a complete description of the system,including current and E/H field,but it requires a detailed description of the test environment and a lot of time calculations.Although the numerical model is accurate,it cannot deeply analyze the behavior of the system.In contrast,the circuit model can provide electrostatic pulse excitation during circuit simulation,simulate and predict the response and protection capabilities of the designed circuit or chip to system-level electrostatic stress.This article designs and optimizes the circuit model of the electrostatic gun based on the IEC 61000-4-2 standard.The specific tasks are as follows:(1)Two new simulation models of contact discharge circuit level,two-capacitor circuit model and three-capacitor circuit model are proposed.Among them,the dual-capacitor model contains two DC power sources,in which the capacitor is charged and then discharged.The three-capacitor model has no DC power supply and is directly discharged by three capacitors containing the initial voltage.The above two models first completed the adjustment of the parameters of each component of the circuit through numerical simulation,and then built a circuit model based on the Cadence simulation platform.The simulation results show that the output waveform has double-peak characteristics and the characteristic parameter values comply with the IEC61000-4-2 standard.The maximum error of the characteristic parameter value of the double-capacitance model is 2.5%,and the maximum error of the characteristic parameter value of the three-capacitance model is 0.25%,which is more accurate than most existing contact discharge models.In addition,by modifying the resistance and capacitance component parameters of the dual-capacitor circuit model,it is extended to the Human Body Model(HBM)modeling under the IEC61340-3-1 standard.(2)Verification of contact discharge circuit simulation model.Considering the influence of the load on the discharge waveform,different resistors and capacitors are selected as the test device for simulation,and the discharge waveform is measured under the same conditions.Considering the influence of the ground wire on the discharge waveform,select ground wires of different lengths for simulation,and measure the discharge waveform under the same conditions.The simulation results of the circuit-level model are in good agreement with the actual test results.Under good conditions,the agreement of the waveform characteristic values reaches 97.5%.