Investigation of Skew on Differential High Speed Links

Abstract: Skew in telecommunication normally means the difference in arrival time of bits transmitted at the same time in differential transmission. As an increasing of transmission data bit rate and more importantly, a data and clock signal rise time of become faster, digital system interconnects became behaving as transmission line. The high speed signals become microwave in nature. The problem is that modern digital designs and verifications require knowledge that has formerly not been needed for a data bit rate of below than 100Mbit but also at the higher frequency range as 5 to 15GHz, however, most references on the necessary subjects are too abstract to be immediately applicable to the skew. For this reason a new method to investigate the skew were introduced, and with which, test board were measured. Since the test boards are made in devise material, and lines on the boards are configured out in distinct structures. In this paper, several methods were applied to find out the skew, and by comparing the results, it could be found that how factors affect the skew, not only the material factor, but some manufactory reason.