3 cells with different drive strengths, each with a P/N ratio of about 2. The Ramp Fall time reported below is an average of when one or the other or both
of the N-transistors connected to <SPAN CLASS="boldred">a1</SPAN>
and <SPAN CLASS="boldred">a2</SPAN> are on.
The Synopsys Liberty format .lib file has the precise timing for each case.