Substrate Injection and Crosstalk in CMOS Circuits

Substrate noise injection is evaluated, at a transistor level, for a 0.25 micron CMOS technology, to determine the mechanisms that contribute to substrate crosstalk. Impact ionization current and capacitive coupling from the drain and source junctions are found to be the most significant contributors to substrate current injection. Their relative importance is evaluated for an inverter, and is shown to depend upon loading and on the frequency of operation.