Numerical Simulation Of The Effects Of Electromagnetic Radiation On Computer Motherboard

In modern electronic devices, the rapid development of circuit density and complexity and the increase of clock frequency have caused more interference between devices. The effects of electromagnetic radiation on print circuit board (PCB) and multichip IC module (MCM) is obviously important to study in electromagnetic compatible (EMC) problems. With lots of PCB technology applications, computer motherboard would also cause electromagnetic radiation while working.The frequency components of computer's radiation signals are very abundance and include a great deal of information. On the other hand, the outside electromagnetic radiation would also disturb and inference computer's normal state. So it's worth analyzing the electromagnetic characteristics distribution when print circuit board is under the radiation of electromagnetic waves.At present, numerical methods such as the Moment Method (MOM), the Finite Element Method (FEM), the Finite-Difference Time-Domain Method (FDTD) and the Transmission Line Matrix Method (TLM) are usually applied to analyze and compute the EMC problem in PCB. But the circuit structure of computer's motherboard is very complicated and the cost of computation is very high. It's difficult to get the solution of the electromagnetic field, and the computing proceed would cost a mass of time.In this paper, a widely used motherboard with advanced functions isregarded as the research project. First this motherboard was precisely scanned, and models of its components are built by using AutoCAD on the proportion of 1:1. Different models are leading-in according to the different characteristics such as geometric structure, relative dielectric constant and conductivity. All kind of models are imported to an EM simulation software which is based on FDTD method. Gauss pluses and continuous electromagnetic waves of different frequencies and incident angles are used as electromagnetic radiation source to the motherboard. The electromagnetic field distribution and characteristics of current variations are simulated and analyzed under radiation of different outside electromagnetic radiation.Time domain simulations and analysis on RF nonlinear devices are mostly based on frequency domain methods, such as harmonic balance, shooting method and so on. Time domain method to simulate and analyze large signals on RF/MW nonlinear devices are presented in this thesis. A nonlinear RF diode is simulated as an example, and the frequency domain results are achieved by Fast Fourier Transform (FFT). This method could be applied to simulate and analyze different kind of RF/MW nonlinear devices. Results of simulation are Time-Domain transforms, and the Time-Domain correspondence could be got from preset motivation of signal pulses. Information of extreme waveband could be got by transition of correspondence from Time-Domain to Frequency-Domain transition, and this proceed required little mathematical preprocessing.