By the signal timing? measuring the setup and hold times in a REAL circuit
You can't measure setup and hold times like this. What you can do is measure the the times you have allowed for setup and hold. The chip might require a setup time of 4ns, and your circuit gives it 3 days -- that doesn't measure the setup time, it measures that you have allowed for a setup time of less than 3 days. Id you measured it ans saw 3.5ns then you would conclude you had not given it sufficient setup time.
You need to understand the difference between the setup time (which is largely fixed for a given chip determined by the propagation delays in the logic) and the signal timing itself.
1) Do you understand propagation delay and how it might affect setup and/or hold times? You should read
this. (And read it until you understand it).
It is like making a cup of coffee. The cup contains a certain amount of water. How much water do you put in the kettle? Clearly you put in the required amount
or more. It's the responsibility of the person making the coffee to fill the kettle with enough water, and the amount you put in does not actually measure the capacity of the cup. In fact if you don't know the capacity of the cup (maybe you haven't chosen a mug yet) you need to put more water in the kettle than the maximum size of the mug you might choose. This analogy breaks down with a cup of coffee because when we pour the water into the cup we can see that it is full and stop (thus providing exactly enough water). For a circuit, we cannot tell exactly when it is set-up, and have to rely on the maximum time it might take (just as if in the coffee case, we had not yet chosen a mug).
2) Do you understand the coffee analogy, and the importance of not having chosen a mug?
For an input with a setup time, we can't know when i is set up. We must provide as least the
maximum time.
You may be familiar with "overclocking" computers. By default the memory timing is set up for the worst case. Many of these settings are related to the setup and/or hold times of the memory. You can fiddle with these, reducing the time allowed until your computer runs as fast as possible without crashing. Here you are deliberately reducing the signal timing below the
maximum setup times. At some point you will reduce them below the
actual set-up time for the chip, and the computer crashes. If you can get timing greater than the actual setup times, and less than the default (typically maximum or greater) then your computer runs faster. You are also in the twilight zone where the computer is no longer guaranteed to work.
BUT, you have not measured the actual setup or hold times, just found some values which work.
3) Do you understand that the process of overclocking a chip may involve timings less than the maximum setup (or hold) times, but greater than the actual setup (or hold) time for that particular chip?
4) Do you understand that in the above case you are doing the equivalent of putting less and less water in the kettle until you no longer have enough to fill the mug, and that the same amount of water might fail for another mug?
f The Data signal happens to "occur" during the clock signals edge which will cause a setup time and hold time error. My question is what does the designer do? add delay networks in the data signal path?
The data doesn't "occur". It might change during the setup or hold times.
Please answer questions 1 to 4 above so I am certain you understand.