| Due to the requirement of the miniaturization of electronic equipment and the requirement of high speed,the circuit board is developing towards high speed and high density.Increased transmission rate means that the rising and falling edges of the signal are as steep as possible.Subsequently,a series of circuit board EMC(Electromagnetic Compatibility)design problems come up.If there is an unsolvable electromagnetic compatibility problem in the circuit board design process,it may lead to the failure of the whole electronic equipment.Therefore,it is of great practical significance to analyze the EMC of PCB(Printed Circuit Board),and then to analyze and optimize the PCB and shielding shell.The thesis focuses on an electromagnetic compatibility problem in the design of an electric field measurement circuit.This thesis uses the CST(Computer Simulation Technology)simulation software to study the radiation characteristics of the circuit board and shielding enclosure.Based on these characteristics,this thesis discusses the revision of reducing the electromagnetic radiation.A solution for EMC design of electric field measurement circuit is proposed.The main work of the thesis is as follows:1.A radiation model for measuring circuit is established.Based on the electric field measurement circuit,the circuit principle is analyzed and the radiation source is given.The electromagnetic radiation status of the PCB was modeled and analyzed.According to the circuit,the radiation source is analyzed,and the circuit board is divided into three sections according to the distribution of the radiation source.The EMR(Electromagnetic Radiation)characteristics of switching power circuit,ADC circuit and CPU crystal oscillator circuit are obtained by simulation and analysis.2.A shielding characteristic simulation model of the circuit shielding enclosure is established.The EMR and leakage characteristics of the shielding shell of the shielding shell is analyzed.The thesis respectively discusses the EMR and leakage characteristics of each radiation source and the shielding shell model according to the three radiation sources.The actual EMR is obtained by emphasizing the shielding effect of circuit board and shielding enclosure.3.Circuit board is optimized based the above analysis of the EMR and leakage characteristics of the shell holes.In order to reduce the electromagnetic radiation,the thesis focuses on the optimization and simulation of the shape and position of the gap in the shield shell.The thesis verifies the feasibility of the model's simulation and optimization by comparing the electromagnetic radiation measurements of before and after optimization. |
PDF Full Text Request