Digital IC Handwriting - MCMM, WNS and TNS

MCMM(Multi Corner Multi Mode), this is a timing analysis mode that must be used in advanced technology.A chip often needs to work under multiple working conditions (corner) and multiple working modes (mode).The reason why MMMC Flow is used is because the device has different characteristics under different PVTs, and the foundary has requirements for timing under these different conditions, that is, timing signoff is required for these conditions.Therefore, it is necessary to add these views in the PR implementation, so that it is possible to enter the PT to do timing signoff after the PR implementation, so as to meet the timing requirements under different views.

WNS(worst negative slack): The worst slack value, indicating the worst performance of the chip.

TNS(total negative slack): The sum of all negative slack values, representing a performance range of the chip.

WNS and TNS are two indicators of time series analysis. The unit is ns, which is an indicator to measure the quality of timing. It is usually a negative number. The more negative values, the worse the performance.