Study On The Interference Of Electrostatic Discharge To Electronic Circuit

Electrostatic discharge is a common electromagnetic hazard source and its process will form high voltage, high electric field, instantaneous large current, and also with strong electromagnetic radiation. The electrostatic discharge influence or destroy the power electronics by many ways, such as it would badly disturb normal work of electronic system and even destroy the circuit board directly, also the strong electromagnetic field caused by electrostatic discharge would couple with the printing line of the PCB and end engender interference voltage. The logical circuit would also be disturbed, for example the high level and the low level may change into each other so it can take a breakdown to the system. Electrostatic discharge has become a common interference source of electronic equipment. So the study on the interference of the electronic circuit caused by electrostatic discharge is very important and useful.Based on the mechanism, characteristic of the ESD and theory of electromagnetic interference and theory of transmission line, this thesis focuses on the research of the interference of ESD to PCB trace. First the thesis briefly introduces the mechanism, characteristic, type and model of the ESD. Expression methods of the ESD current are discussed and study the common two kinds of methods. Analytic method can make a calculation directly, equivalent circuit method can reflect the physical process and list three circuit model, including simple circuit RLC model, double RLC model and nine elements model. Based on the theory of EMC, the thesis study the coupling of the ESD, analyze the coupling of magnetic field and electric field and radiation coupling. Then study the transmission line theory and calculation method, especially on the four calculation methods including Bergeron, Difference method, FDTD and analysis method. And do some simulation and experimental research on Bergeron to points out the feasibility of the method. Then do much research on the interference of ESD to PCB, pointing out the problem and adopt to use transmission line method. Following the thesis make equivalent model of two typical structure of PCB trace and calculate the transmission line parameters of the trace. Next do the simulation of the interference of the equivalent model. During the research this thesis use the ESD waveform simulated by circuit is comply with the IEC standard. Meanwhile do the research of the interference of ESD to PCB ground, make the equivalent model and calculate the disturbance voltage. Finally do exploration tests.