A physical connection between two PCI Express devices is broken down into sub-parts, as can be seen on the current slide. A lane consists of signal pairs in each direction (dual simplex transmission), with each signal pair made up of a pair of two wires. These two wires are used to transmit the differential signals across the lane. The peak-to-peak signaling voltage at the transmitter ranges from 800mV to 1200mV, while the differential peak voltage is half of these values.

