Waveform approximation technique in the switch-level timing simulator BTS

In this paper an accurate and efficient switch-level timing simulator is described. The high accuracy is attributed to a new waveform approximation technique, which includes delay estimation and slope estimation. Efficient delay and slope calculations are accomplished through a switch-level simulation instead of using a transistor-level simulation. A new approach for delay estimation is presented, and it models the delay behavior of an RC tree by two equations: a dominant delay equation and an offset delay equation. Both are derived by a special process to fit the surface built by experimental data measured from the actual delay behavior of a CMOS gate. The results show good agreement with SPICE.