Delays and State Elements

Stage Delays Add Before the Next Edge

A timing path closes only after each stage delay is summed. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Stage delays add before the next capture edge

The three stages take 2 seconds, 3 seconds, and 1 second.

2+3+1=6 s2+3+1=6\ \text{s}
Delay chainEach stage label contributes to the total.period 8 sedges 4edge 1 at 8 slast 24 sd1 2 sd2 3 sd3 1 stotal 6 srequired at 14 sbudget 6 sslack 0 saccepted

The relative delay budget is period minus setup

The clock period is 8 seconds and setup is 2 seconds, leaving a 6 second delay budget.

8 s+(−2 s)=6 s8\ \text{s}+(-2\ \text{s})=6\ \text{s}
Delay budgetThe relative budget and absolute required time are separate.period 8 sedges 4edge 1 at 8 slast 24 sd1 2 sd2 3 sd3 1 stotal 6 srequired at 14 sbudget 6 sslack 0 saccepted

Using the whole budget gives zero slack and still passes

The total delay equals the budget, so slack is 0 seconds and the path is accepted.

6 s+(−6 s)=0 s6\ \text{s}+(-6\ \text{s})=0\ \text{s}
Zero-slack pathZero slack is accepted by the deterministic gate.period 8 sedges 4edge 1 at 8 slast 24 sd1 2 sd2 3 sd3 1 stotal 6 srequired at 14 sbudget 6 sslack 0 saccepted