Equivalent waveform propagation for static timing analysis

This paper proposes a scheme that captures diverse input waveforms of CMOS gates for static timing analysis (STA). Conventionally latest arrival and transition times are calculated from the timings when a transient waveform goes across predetermined reference voltages. However, this method cannot accurately consider the impact of waveform shape on gate delay when crosstalk-induced nonmonotonic waveforms or inductance-dominant stepwise waveforms are injected. We propose a new timing analysis scheme called "equivalent waveform propagation." The proposed scheme calculates the equivalent waveform that makes the output waveform close to the actual waveform, and uses the equivalent waveform for timing calculation. The proposed scheme can cope with various waveforms affected by resistive shielding, crosstalk noise, wire inductance, etc. In this paper, we devise a method to calculate the equivalent waveform. The proposed calculation method is compatible with conventional methods in gate delay library and characterization and, hence, our method is easily implemented with conventional STA tools.