3. Constraints linked to the speed of computer systems

Respecting signal integrity is the most important factor to consider when designing high-speed computer boards. When transferring signals between two integrated circuits, signals must be altered as little as possible in order to retain their essential electrical parameters (duration and amplitude) between the output of the first circuit (usually a buffer) and the input port of the second. Signal distortions are caused either by the characteristics of the transmission line (attenuation and parasitic oscillations), or by noise (surges induced during processor switching or linked to the DC power supply), or by parasitic electromagnetic coupling induced in the conductor by another active conductor or external radiation. These effects are all the more noticeable now that operating voltages are becoming ever lower, in order to reduce the power dissipated in processors and integrated circuits....