The iso-length of high-speed digital PCB board is to keep the delay difference of each signal within a range, to ensure the effectiveness of the data read by the system in the same cycle (the delay

difference exceeds one clock cycle will misread the data of the next cycle), generally requires that the delay difference does not exceed 1/4 clock cycle, and the line delay difference per unit length is

also fixed. Copper thickness, the plate structure is related, but the line is too long will increase the distributed capacitance and distributed inductance, so that the signal quality, so the clock IC pin is

connected to the RC end, but the snake wire does not play the role of inductance, on the contrary, the inductance will make the signal in the rising element of the high-order harmonic phase shift,

resulting in deterioration of the signal quality, so the serpentine line spacing is at least twice the line width. The smaller the rise time of the signal, the more susceptible it is to distributed capacitance

and distributed inductance.

Because of the different applications have different roles, if the serpentine path appears in the computer board, it mainly plays the role of a filter inductance, improve the anti-interference ability of

the circuit, the serpentine path in the computer host board, mainly used in some clock signals, such as CIClk, AGPClk, its role has two points: 1, impedance matching 2, filter inductance.

For some important signals, such as HUBLink in the INTELHUB architecture, a total of 13 roots, running 233MHz, must be strictly equal in length, in order to eliminate the hidden dangers caused

by time delay, winding is the only solution. Generally speaking, the line distance of the serpentine line is >=2 times the line width. The snaking line on the PCI board is to adapt to the line length

requirements of PCI33MHzClock. If in the general ordinary PCB board, is a distributed parameter LC filter, can also be used as the inductor of the radio antenna, short and narrow snake wire can be

used as a fuse and so on.