Timing

Delay

The amount of time passed before the output follows the input is the propagation delay. It is the maximum delay from input to output. During this time, the output is unpredictable.

Since the output is unpredictable during the time after input and before propagation delay passed, it is possible to read an output during this time. This is the contamination delay: the minimum delay from input to output.

The reason for the unpredictability at contamination delay is due to physics.

We generally do not measure the delays of an individual component, which involves calculating the timing of the critical path. They are usually given.

The setup time is the minimum time between input stabilization and clock switching. The hold time is after.

Flip Flop

Propagation delay and contamination delay of clock to Q is is denoted differently for flip-flops. $t_{ccq}$ and $t_{pcq}$