When I turn on the LeonardoSpectrum™ Extended Optimization option, why does the software select the pass with the smallest area when I chose to optimize for delay, or the shortest delay when I chose to optimize for area?

• The software will choose the smallest design implementation regardless of wether you specify to optimize for area or delay. Figure 1 shows an example where the frequency equals 100 MHz/10 ns.

For both area and delay settings, Pass 1 will be chosen since it is the smallest pass that meets the timing requirements.

If a target frequency has not been specified or the design does not meet the specified target frequency requirements, then:

• The software will choose the pass with the smallest design for an area setting, and the software will choose the pass with the fastest design for a delay setting.

However, there are instances where the software may not adhere to this second rule, if one pass has a design implementation which is considerably smaller or faster. For example, if area is selected and the smallest implementation pass has a very high delay, a different pass may be chosen with slightly more area but a much better delay. The LeonardoSpectrum software uses its own cost function to determine which pass should be chosen in these cases.