Early Next Change Fails Hold After Capture - Electronic Circuits XII: Clocks, Latches, and Timing Closure Step by Step

Negative hold slack rejects the capture attempt. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

An early next change makes hold slack negative

The next data change is at 17/2 seconds, which is too soon after the edge.

{17\over 2}\ \text{s}+(-8\ \text{s})+(-1\ \text{s})={-1\over 2}\ \text{s}

Earlier next-change rows cross the hold boundary

The data-arrival row stays safely before setup while the next change moves toward the edge.

\begin{array}{c|c|c}t_{\text{next}}&s_{\text{hold}}&\text{gate}\\9\ \text{s}&0\ \text{s}&\text{pass}\\\tfrac{17}{2}\ \text{s}&\mathord{-}\tfrac{1}{2}\ \text{s}&\text{fail}\\\tfrac{33}{4}\ \text{s}&\mathord{-}\tfrac{3}{4}\ \text{s}&\text{fail}\\\end{array}

The hold failure rejects the same capture attempt

The hold slack is -1/2 seconds, so the status is rejected.

\text{accepted bit}=0