Printed circuit board

Abstract

The invention relates to a printed circuit board, comprising a first reference layer, a first signal layer, a second signal layer and a third signal layer which are overlapped; the first differential pair is arranged on the first signal layer in an edge coupling way, and the first differential pair takes the first reference layer as the reference layer; the space between the first signal layer and the second signal layer is larger than that between the first reference layer and the first signal layer; and a second differential pair is arranged in the second signal layer and the third signal layer in a wide-edge coupling way. The printed circuit board properly reduces the space between the first signal layer and the third signal layer and increases the space between the first signal layer and the second signal layer, and differential pairs are arranged on the second signal layer and the third signal layer in a mode of broadside coupling; compared with the prior art, the printed circuitboard reduces the use frequency of the additional reference layer, increases the number of signal layers, and improve the wiring density of the printed circuit board.

Description

technical field [0001] The invention relates to a printed circuit board, in particular to a printed circuit board with high wiring density. Background technique [0002] In today's multilayer printed circuit boards, differential pairs on inner layers are often used to transmit signals. Such as figure 1 As shown, most of the differential pairs in the traditional printed circuit board are laid out in the way of edge-coupled (edge-couple), which means that the two differential transmission lines of the differential pair are coupled to each other in the same signal layer of the printed circuit board. . In order to ensure the quality of signal transmission during actual wiring, a reference layer must be provided above or below the differential pair. For example, the two differential transmission lines 171 and 172 of the differential pair 17 are coupled to each other in the same signal layer 12 of the printed circuit board, and reference layers 11 and 13 are provided above and ...

AI Technical Summary

Problems solved by technology

Therefore, since the two differential transmission lines of the traditional edge-coupled differential pair are laid on the same layer, for a printed circuit board with more than six layers, at least one middle layer of the printed circuit board needs to be occupied as a reference layer. Occupies a large wiring space, resulting in a low wiring density of the printed circuit board, which does not meet the trend of smaller and smaller information products today

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