Electromagnetic Compliance Design In Multifunction Radio Digital Communication Terminal

In this paper the EMC (electromagnetic compatible) design of a multifunctional wireless communication terminal product is studied ,including the analysis of special EMC performance requirements of the terminal, summing up the EMC design procedure and investigation of the electromagnetic interference suppression technologies.According to the characteristics of the terminal, its EMC performance should not only meet related EMC regulatory body's requirement but also provide assurance for the implementation of wireless communication system and other product's function feature. This is because that the reception performance of wireless communication system is very susceptive to the inner interference of the product, and the other susceptive circuits such as audio circuit and microprocessor, are also very easily disturbed by the high power wireless transmitter.Based upon the related EMC theory, the spectrum characteristics and propagation mechanism of the interference are studied. In the product, the electromagnetic interference is mainly from the multi-media application processor and other digital devices, and the spectrum width of interference is depending on the digital signal's rise/fall time and the digital devices'working frequency. The interference in the product is mainly propagating through radiating, and cause a reduction of the product's wireless reception performance.Furthermore, this paper presented a detailed EMC design case. Through this case, some essential electromagnetic interference suppression techniques are introduced, and these techniques'interference suppression effects are investigated through the comparison of interference spectrum, reception sensitivity under before and after these techniques were adopted.At the end, the product's EMC design procedure and necessary interference suppression techniques are summarized. For this multifunctional wireless communication terminal product, its EMC design should obey the following procedure, including product EMC performance requirement analyzing, electromagnetic interference source and propagation mechanism analyzing and the comprehensive implementation of interference suppression techniques. In this product, the following interference suppression techniques are essential and should be adopted, including electromagnetic interference filtering, PCB level electromagnetic shielding, interconnecting cable's shielding and advanced PCB design techniques for EMC.