This communication presents the evidence of a degradation effect causing important reductions in the delay of a CMOS inverter when consecutive input transition are close in time. Complete understanding of the effect is demonstrated, providing a quantifying model. Fully characterization as a function of design variables and external conditions is carried out, making the model suitable for using in library characterization as well as simulation at a transistor level. Comparison with HSPICE level 6 simulations shows satisfactory accuracy for timing evaluation.

Comisión Interministerial de Ciencia y Tecnología TIC 95-0094