urgent: about the time tagging circuit for phase detector

How to implement the time-tagging
circuit and firmware, which has a gain of Kdet = 1bit/ns.

This phase detector is for the DPLL, using the digital loop filter.

Could someone kindly provide some materals about the time tagging circuit?

Thanks in advance!

What do you mean time tagging? You have two AC signals and you want to get the phase difference between the two?

Re: urgent: about the time tagging circuit for phase detecto

Yes. I want to measure the phase differents between two signal( Clock) with the 1ns resolution.


Maybe the FPGA or EPLD is not enough for this measure, obviously, this require 1000MHz main clock to achieve 1ns resolution.

So I think the phase differents should be tranlate to the analog signal, and then we can convert to digital signal. What I mean is expand the width of the pulse and then measure it to achieve high resolution.

Could you have some good ideas?

Your clock signal has a 50% duty cycle? To think it is quite easy to measure if your pulse with is much larger than 1ns.

But the problem is with a frequency like that small, I think it will require a very fast timer to catch up.

All you have to do really is start a timer when the first signal reached its rising or falling edge and stop the timer when the second signal reached its rising or falling edge, there you can know the time difference between the two and convert them to phase. To get the phase difference in radians, it will be quite easy by plotting your original signal.

Now I am still thinking on how to make your signal resolution bigger.

Maybe a use of frequency divider will do, maybe if you use the same frequency divider for both, their phase differences will still be retained.

i know the time-tagging phase detector is often used in digital pll, where, the reference input is a very low frequncy signal, for example, 1pps from a gps receiver, the local oscillator is a 10MHz ocxo or rubidium clock.

this topic is more like a analog problem, so i suggest move this topic to "RF, Microwave, Antennas and Optics" , where may be you can get more help