SizWind, can you elaborate some more on the description of the pulse you are trying to measure. Sporadic vs. a given measurement frequency.
I can think of several devices that have PWM/window comparison logic to resolve to hundreds if not tenths of pSec.
How often do you require to make a measurement, how accurately, and at what cost and complexity?
When you say 500ps is that plus and minus, and is that resolution or accuracy?
What is the frequency of the signal you are measuring eg are the pulses only a few times 500ps wide or are they millions of ps wide?
You could use discrete logic, but handling 2GHz signals on a board could be tricky - normally this level is hidden away inside chips. You might be able to use some form of programmable logic, but 2GHz is pretty fast for an FPGA.
If you don't need to take measurements of every pulse, or not very frequently, you could even use analogue techniques eg charge a capacitor up while the pulse is high using one value of resistor, then count how long it takes you to discharge the capacitor again using a much higher value of resistor (the ratio of the resistors allowing for you to make the measurement over a lot longer period and hence use a much slower clock). Of course noise etc need to be taken into account.
There are lots of clever variants of this, and they can potentially be used to measure things very accurately, at the expense of time.
I am designing a board-level circuit to measure pulse width, in which I need a high-precision timer. I want to use a high-speed counter to implement the timer. Since the timer requires an accuracy of 500ps, this implies that the clock to the counter has to run at a frequency of 2GHz. Since I am not designing chip-level circuit, I would like to purchase such an external timer/counter which achieves such precision. Does Anyone have an idea what to buy? If such high precision timer is not easily available in the market, is there anyway I can solve the problem through other means?