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As data rates continue to increase, PCB designers are moving toward serial buses with differential signaling. High-speed serial interfaces such as PCI-Express, 10 Gigabit Ethernet XAUI, OC768 and CEI use differential signaling for transmitting and receiving data. FGPA devices with embedded high-speed transceiver blocks provide an easy, cost-effective approach for implementing these high-speed applications, as illustrated in FIGURE 1.
Differential signaling uses two output drivers to drive two independent transmission lines. One driver carries one bit, the other its complement. The difference of the two signals, measured between the two traces, carries the desired information. A differential pair is a pair of transmission lines with some amount of coupling between the two legs of the pair.
