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PCB serpentine line purpose

date:2017-09-12 09:53:12

Chenfei Electronic Tech Co.,Ltd is a contract electronic manufacturer. Today we introduce PCB serpentine line purpose.Any a walk line on the PCB in the case of by high frequency signal to the signal caused by time delay, serpentine linear compensation is the main purpose of "the same group of related" delay smaller part of the signal lines, these parts are often not or less than other signals by other logic to handle;The most typical is the clock line, it usually can be treated with any other logic, so the time delay will be less than other related signal.
High speed digital PCB line length is such as to keep the signal delay differential in a range, to ensure the effectiveness of the read data in the system in the same period (delay less than one clock cycle wrong when they read the data of the next cycle).General requirements delay no more than a quarter of the clock cycle, unit length line delay difference is fixed, delay with the line width, line length, copper thickness, plate layer structure,But the line is too long will increase the distribution of distributed capacitance and inductance, make the signal quality, so the clock IC pins are general RC termination, but snake go line, not the inductance of the role,On the contrary, inductance can make the signal of the rise in the yuan higher harmonic phase shift, causing signal quality deterioration,Serpentine line spacing is required at least twice as much as the line width, the smaller the rise time of a signal, the more vulnerable to the influence of the distribution of distributed capacitance and inductance.
Because of different applications have different functions, if serpentine line appeared in the PC board, the main play the role of a filter inductance, improve the anti-interference ability of the circuit, the computer motherboard the serpentine line,Mainly used in some of the clock signal, such as CIClk AGPClk, its function has two points:1, the impedance matching 2, filtering inductance.On some important signal, such as INTEL HUB HUBLink in architecture, a total of 13,233MHz,Requirements must be strictly, to eliminate the delay caused by the hidden trouble, winding is the only solution.In general, serpentine lines to go the distance > = 2 times the line width.Sinusoidal line in the PCI board is to meet the requirements for PCI 33 mhzclock line length.If, in the ordinary PCB is a distribution parameter of the LC filter, but also as a radio antenna inductance coil, short and narrow serpentine go line to do the fuse and so on.