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What are the characteristics of EMC system integration?

Release time:

2022-10-13 11:46

Source:

EMC system integration manufacturers believe that active devices in hybrid circuits generally use bare chips, and when bare chips are not available, the corresponding package chips can be used. In order to obtain the appropriate EMC characteristics, surface mount chips should be used as much as possible. When choosing a chip, under the premise of meeting the technical specifications of the product, try to choose a low-speed clock, never use AC when you can use HC, and CMOS4000 can work without HC. Capacitors should have a low equivalent series resistance, which can avoid large attenuation of the signal. The package of the hybrid circuit can use the base and cover of the fungible metal, which can be welded in parallel and shielded well.

电磁兼容系统集成

EMC system integration manufacturers believe that when dividing the layout of a hybrid microcircuit, there are three main factors to consider first: the number of input/output pins, device density and power consumption. A practical rule is that the area of the chip components is 20% of the substrate, and the power consumption per square inch does not exceed 2W.

EMC system integration manufacturers believe that in principle, related devices should be placed as close as possible to each other in terms of device layout, digital circuits, analog circuits, and power circuits should be placed separately, and high-frequency circuits should be separated from low-frequency circuits. Devices susceptible to noise, small-current circuits, high-current circuits, etc. should be as far away from the logic circuit as possible. Clock circuits, high frequency circuits, and other major sources of interference and radiation should be placed independently, away from sensitive circuits. Input chips should be located near the I/O outlets of the mixed circuit package. High-frequency components should be connected as short as possible to reduce distribution parameters and mutual electromagnetic interference. Components susceptible to interference should not be too close to each other, and inputs and outputs should be as far away as possible.

EMC system integration manufacturers believe that oscillators should be located as close as possible to the location where clock chips are used and away from signal interfaces and low-level signal chips. Components should be parallel or perpendicular to the side of the substrate, components should be arranged as parallel as possible, so as to reduce the distribution parameters between the components, but also in line with the manufacturing process of hybrid circuits, easy to produce. On the hybrid circuit substrate, the lead pads for power and ground should be arranged symmetrically, and multiple I/O connections for power and ground should be distributed as evenly as possible. The mounting area of the bare chip is connected to the most negative potential plane.

EMC system integration manufacturers believe that when a multilayer hybrid circuit is elected, the sandwich arrangement of the board varies depending on the specific circuit, but generally has the following characteristics.

(1) power and ground layers are distributed in the inner layer, which can be regarded as a shielding layer, which can well suppress the common mode RF interference inherent in the circuit board and reduce the distributed impedance of high frequency power.

(2) the board power supply layer and ground layer as close as possible to each other, ground layer is generally above the power supply layer, so that the interlayer capacitance can be used as a power supply smoothing capacitance, while the ground layer can shield the radiation current distributed in the power supply layer.

(3) The wiring layer should be arranged as close as possible to the power supply or grounding layer to produce flux offset.

 

Century Wisdom (Suzhou) Testing Technology Co., Ltd

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