pcbhi

PCB EMC design 1）Analysis of signal spectrum A1 = 2τ / T A2 = 0.64 / T f A3 = 0.2 / T tr f2 The shorter the rise (or fall) time, the richer the high frequency components of the signal. （2）Analysis of interference sources ΔI Noise interference Common mode interference and differential mode interference (a)Differential mode radiation （b）common mode radiation Crosstalk When a high frequency current flows through a signal line, the interference voltage will be induced on the signal line adjacent to the PCB board. （3）Wiring design technology ◊  When wiring, make all signal loop areas (especially high-frequency signals and sensitive signal loop areas) as small as possible. ◊  High-speed signal lines should not be crossed over the partition area or over the unrelated reference plane. ◊  In analog circuit and RF circuit designs, as well as in dual panels without a power ground plane, the guard wires are often used to prot...

Tips for designing high frequency board layout (1) High-frequency circuits tend to have high integration and high wiring density. The use of multi-layer boards is both necessary for wiring and an effective means to reduce interference. (2) The less the lead bend between the pins of the high-speed circuit device, the better. It is better to use full straight line for high frequency circuit wiring. If turning is needed, 45 degree break line or arc turning can be used. Once meeting this requirement, the external transmission of high frequency signals and the coupling between them can be reduced. (3) The shorter the lead between the pins of high frequency circuit devices, the better. (4) The fewer lead layers alternating between pins of high frequency circuit devices, the better. It means that the fewer Via holes used in the process of component connection, the better. Reducing the number of Via holes can significantly improve the speed. (5) High-frequency circui...

Golden rules of PCB design Despite the increasing integration of semiconductors, many applications have ready-to-use system-on-a-chip, and many powerful and out-of-the-box development boards are becoming more readily available, but the use of electronics in many use cases Still need to use a custom PCB. In a one-time development, even a common PCB can play a very important role. PCB is the physical platform for design and the most flexible component for the original components for electronic system design. The following sections describe the most effective design rules that electronic design engineers should keep in mind when implementing design layout and commercial manufacturing using design software. Rule 1: Select the correct grid, set and always use the grid spacing that matches the most components. Although multi-grid seems to have significant utility, if engineers can avoid problems when setting up the interval and maximize the application of the board if they can thin...

Through hole design skills Via hole is one of the important components of multi-layer PCB.The cost of drilling is usually 30%-40% of the cost of PCB board.To put it simply，each hole in the PCB can be called a via hole .In terms of function,the vias can be divided into two types:one is used as an electrical connection between the layers;the other is used for fixing or positioning the components.In terms of process,the vias generally divided into three types:blind via、buried via and through via. The blind via are located on the top and bottom surface of the printed circuits board,and have a depth for the connection of the surface circuit to the underlying inner circuit.The depth of the holes usually does not exceed a certain ratio(aperture) .The buried hole is a connection hole located in the inner layer of PCB,which does not extend to the surface of circuit board.The above two types of holes are located in the inner layer of circuit board,and are made by a t...

The Role of Laying Copper There are several reasons for laying copper in general. 1.EMC.For large areas of power supply laying copper , will play a shielding role, such as PGND play a protective role. 2.PCB process requirements. Generally, in order to ensure the plating effect, or the lamination is not deformed, the PCB board with less wiring is coated with copper. 3.Signal integrity requirements.Give high frequency digital signal a complete backflow path, and reduce DC network wiring. Of course, there are also heat dissipation, special device installation require to lay copper and other reasons. First, a great advantage of laying copper is to reduce the ground wire impedance (a large part of the anti-interference is caused by the reduction of the ground wire impedance). There are a lot of peak current in the digital circuit, so it is more necessary to reduce the ground wire impedance. Second, the significance of laying copper ： 1. Lay...