A block-based statistical timing analysis technique is provided in which the
delay
and arrival times in the circuit are modeled as random variables. The arrival times
are modeled as Cumulative Probability Distribution Functions (CDFs) and the gate
delays are modeled as Probability Density Functions (PDFs). This leads to efficient
expressions for both max and addition operations, the two key functions in both
regular and statistical timing analysis. Although the proposed approach can handle
any form of the CDF, the CDFs may also be modeled as piecewise linear for computational
efficiency. The dependency caused by reconvergent fanout is addressed, which is
a necessary first step in a statistical STA framework. Reconvergent fanouts are
efficiently handled by a common mode removal approach using statistical "subtraction."