Electrical connector having contact wafers with a step structure

An electrical connector comprising:

• a plurality of contact wafers side by side stacked with one another along a transverse direction,
• each of said contact wafers including:
• an insulative housing with a lying U-shaped configuration viewed along said transverse direction so as to form a receiving slot in said U-shaped configuration;
• a pair of upper contacts and a pair of lower contact disposed in the housing and space from each other and on two sides of the receiving slot in a vertical direction perpendicular to said transverse direction, the pair of upper contacts being spaced from each other in the vertical direction with a contacting end of one upper contact located in front of that of the other upper contact, the pair of lower contacts being spaced from each other in the vertical direction with a contacting end of one lower contact located in front of that of the other lower contact, wherein the contacting end of said one upper contact is aligned with the contacting end of said one lower contact in the vertical direction, and the contacting end of the said other upper contact is aligned with the contacting end of said other lower contact;
• and
• an upper differential pair cable connected to the pair of upper contacts, a lower differential pair cable connected to the pair of lower contacts, respectively.