AN INVESTIGATION OF DELTA-I NOISE ON INTEGRATED-CIRCUITS

The delta-I noise is the phenomenon of the voltage induced between the power conductors (e.g., the ground and the V(cc) planes) when a circu it connected between them switches from one state to another. This noi se can endanger the performance of other circuits on the same chip or the printed-circuit board. In the existing literature, the noise has b een considered primarily for integrated circuits, and it has been attr ibuted solely to inductive effects. In this paper we show that the phy sics of the noise is more complex, and that it is related to the wave propagating effects. The delta-I noise should be present not only on i ntegrated circuits (chips), but also on multilayered boards, where thi s noise should be pronounced when the transients are of the order of 1 ns or less. The investigations of the delta-I noise are carried out o n a simplified model of power planes, using a wire-antenna numerical s imulation program. The model includes the wave propagation effects, as well as radiation, but it does not include the effects of the dielect ric filling out the space between the planes. The results of the analy sis clearly show that the inductive effects are important only for slo wer transients. However, for fast digital circuits the power planes ac tually form a resonator, which can have a high quality factor, and the delta-I noise can build up to very high-voltage levels.