Lumped delay is delay assigned as a single delay in each module, mostly to the output gate of the module. The cumulative delay of all paths is lumped at one location. The figure below is an example of lumped delay. This figure is similar as the figure of the distributed delay, but with the sum delay of the longest path assigned to the output gate: (delay of gate 2 + delay of gate 3) = 9.
Figure 2: Lumped delay
As can be seen from Figure 2, gate 3 has got a delay of 9. When the input of this gate changes, the output of the gate changes after the delay value specified.
The program corresponding to Figure 2, is very similar to the one for distributed delay. The difference is that only or - gate 3 has got a delay assigned to it:
This model can be used if delay between different inputs is not required.