A conductive transmission line structure includes a first conductive transmission line and a second conductive transmission line. A first segment and a second segment of the first conductive transmission line are respectively disposed adjacent to a third segment and a fourth segment of the second conductive transmission line. Line widths of the first segment and the third segment are respectively smaller than line widths of the second segment and the fourth segment. A spacing between the first segment and the third segment is smaller than a spacing between the second segment and the fourth segment. The first segment and the third segment provide a first impedance, and the second segment and the fourth segment provide a second impedance. The first impedance is smaller than the second impedance. The first and the third signal transmission nodes receive a differential signal pair.