| With the continuous development of emerging technologies,especially the emergence of new application scenarios in new industries such as new energy vehicles,5G communication,and artificial intelligence,the development of integrated circuits(ICs)has shown a trend of miniaturisation in size,complexity in structure,increased integration,increased data exchange rates and higher operating frequencies,which has brought about serious electromagnetic compatibility(EMC)problems,one of the important causes of EMC problems in ICs is radiation emission.Therefore,accurate and reliable testing of IC electromagnetic radiation is of great importance for the EMC design of integrated circuits.The transverse electromagnetic(TEM)chamber method,as the most widely used method of measuring IC radiation emission,is currently mainly used by placing the IC in the chamber and then characterising the test results of four angles(0°,90°,180°,270°)as the IC’s electromagnetic radiation,as the IC’s radiation has an angular effect,the four angles alone cannot accurately test the IC electromagnetic radiation level.The study of IC testing methods based on TEM chambers can improve the accuracy of IC radiated emission testing and is of great importance to the EMC design of ICs.In this paper,the following studies on the angular effects of electromagnetic radiation in TEM chambers have been carried out by a combination of simulation and testing.Firstly,this paper first investigates the angular effect of electromagnetic radiation from microstrip lines in a TEM cell and then extrapolates it to the actual IC to be measured.It is found that the measured IC radiation is mainly transmitted through electric field coupling and magnetic field coupling,where the electric field coupling is basically constant and the strength of the magnetic field coupling is angle-dependent.A full-wave simulation model of a TEM cell suitable for IC radiation testing was built in the CST software,and a passive circuit was used for the simulation.The radiation levels at each angle were obtained by parametric scanning of the angle at which the circuit model was located,and the scanning results proved the existence of angular effects in IC radiation.Secondly,in order to accurately test the maximum radiation emission of the integrated circuit,this paper designs and processes a circular PCB test board and a square PCB test board according to IEC standards,and also builds a TEM chamber-based test system for electromagnetic radiation of the integrated circuit.Different operating programs were burned into the chips to be tested on the two test boards so that the chips could work in different operating modes,such as serial communication mode,ADC digital-to-analogue conversion mode and so on.When the chip is in the same mode,the circular test board is tested at 10°intervals for multiple angles and the square test board is tested at the four angles(0°,90°,180°,270°)specified by the conventional method.The test results found that the results of the circular test board in different modes are greater than those of the square test board.The test results of the circular test board are more representative of the electromagnetic radiation level of the chip.Finally,this paper collates test data from various angles in different modes to extract the radiation pattern and magnetic dipole of IC radiation and verifies them by a near-field scanning system.The scanning results are basically consistent with the model of multi-angle test results based on TEM chambers.Thus through the angular effect of IC radiation in the TEM cell,using a circular test plate at multiple angles,the radiation patterns and magnetic dipoles of ICs in space can be extracted,contributing to the EMC design of ICs. |
