An efficient model of the CMOS inverter for nanometer technologies

In this paper, an approach for modeling the output waveform and the propagation delay of the CMOS inverter in nanometer technologies is introduced. An initial output waveform is calculated by solving the corresponding differential equations of the circuit only for the conducting transistor. The effect of the short-circuit current is treated as an additional charge that has to be discharged through the conducting transistor thus causing a time-shift of the initial output waveform. The dynamic behavior of the loading transistor is analyzed and the current due to its bulk-to-drain coupling capacitance is taken into account. Also, sub-threshold current is taken into account where significant.