Chapter 14. Differential Traces and Impedance
We generally think of signals propagating through our circuits in one of three commonly understood modes: single-ended, differential mode, or common mode.
Single-ended mode is the mode we are most familiar with. It involves a single wire or trace between a driver and a receiver. The signal propagates down the trace and returns through the ground system.
Differential mode (more properly called odd mode) involves a pair of traces (wires) between the driver and receiver. We typically say that one trace carries the positive signal and the other carries a negative signal that is both equal to, and the opposite polarity from, the first. Since the signals are equal and opposite, there is no return ...