EMI shielding essentially protects the electronics of a device or system. Simply put, an EMI shield is a barrier against electromagnetic interference, usually consisting of a metal shield that absorbs interference that travels through the air. EMI shielding either surrounds the sensitive electronic components of the device to protect it from other devices, or surrounds the transmission electronics in the device to prevent emissions.
EMI shielding absorbs the signal when it reaches or emanates from your device, creating a current in its body, and the ground connection or virtual ground plane absorbs this current. For example, today’s smartphones consist of many complex electronic devices that must work simultaneously for the phone to function properly, and EMI shielding prevents these complex components from reacting to random signals and waves that can adversely affect the device .
The source of EMI can sometimes be a naturally occurring environmental event, such as electrical storms and solar radiation; but more often than not, the source of EMI is another electronic device or electrical system. While any electronic device can generate EMI, certain devices and components (such as cell phones, welders, motors, and LED screens) are more prone to interference than others.
Since electronic devices rarely operate alone, products are often designed to operate in the presence of a certain amount of EMI. This is especially important in military-grade and avionics equipment and equipment where superior reliability is required in all situations.
EMI suppression strategy
EMI is a system problem. Each energy consuming element and each signal line in the system will affect the EMI performance of the system, and in many cases, the impact is estimated. Therefore, correct methods are needed to solve it.
Conducted EMI and radiated EMI are completely different in the cause and transmission path, and their frequency band ranges are also completely different, which determines that the measures to suppress them will also be very different. In this paper, the causes of these two kinds of EMI are studied respectively, and some suppression methods are given in combination with practice.
To solve the EMI problem, we need to have a clear overall idea: first, we should carefully analyze the characteristics of the circuit system, find the main sources of EMI, and reduce the EMI generated by it through various measures on the circuit board. If the detection requirements cannot be met after weakening, consider shielding again. This method can be used to deal with the EMI problem with a targeted view, and can often achieve the goal with the lowest cost and the shortest time, with twice the result with half the effort.
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