circuit for time period measurement with picosecond resolution

There is a waveform with period in sub-microseconds. Is it possible to measure the period with picosecond resolution without going for large circuits?
There are Vernier-time-to-digital converters are capable of achieving picosecond resolution but can measure upto some nanoseconds of events to avoid large circuits.
Please share some thoughts.

A common comparator, counter and a register (both with reset) could be used.

Prototyp_V1.0 please share some more info.

Picosecond resolution implies clock frequencies in the terrahertz region.
That's not doable with standard circuits.

Define "large circuits"...

The problem is well known e.g. from high performance ultrasonic doppler flow measurements. A usual approach is a combination of a digital counter for the coarse timing and an analog or digital (utilizing gate propagation delays) TDC. There are even single chip flow measurement solutions with a few 10 ps resolution.

A basic problem is that the jitter of the digital circuit must be fairly below the intended resolution.

Dont need such high performance systems. As I mentioned in starting post, vernier time to digital converters, pulse compression time to digital converters are capable of achieving resolution less than picosecond in current technology. They dont require external clocks. Hence no problem of jitter. They rely on delay cells (not picosecond delays) and for measurement of large intervals number of delay cells becomes huge. Eg. with 1 ps resolution, measurement of a interval of 1 us requires at least 1 million delay cells. So they have created cyclic time to digital converters to use the same set of delay elements over and over again until measurement is made. However in cyclic converters you have to delay the interval to be measured by at least the intervals duration. So it will take a long time to perform measurement of large intervals.

I am really stuck with this problem. Can this be done with two TDCs one with nanosecond resolution and another with picosecond resolution? But how to identify when picosecond circuit will take over nanosecond circuit?

Sorry, your latest post seems only to confuse the initial problem description. Apparently you also didn't understand the simple idea of combining a slow digital time measurement with fast TDC. Why are you discussing one million gate delay cells? Just pointless.

Dont need such high performance systems

Click to expand...

??? ps resolution for µs times is obviously much higher measurement performance than ps over only ns intervals.

A "cyclic time converter", however you implement it, will bring up a similar jitter problem as a digital counter, because it's multiplying the jitter of the basic delay element. So no real solution.

FvM,
Sorry, didn't mean to confuse anyone, I misunderstood.
I am trying to avoid a clocked counter for coarse measurement. Because I have to generate a clock. I am thinking of a nanosecond resolution TDC for coarse measurement and then picosecond resolution TDC for fine measurement. But how will the circuit understand when to switch between the two resolutions?

The problem is that the low resolution timer has to trigger the high resolution interval measurement. Besides all detail problems, this works quite well for a clocked digital circuit. What's the problem with generating a clock?

Clock is ok. But suppose that when the measurement should start the clock edge may not be present exactly at that instant, maybe before or after, which will lead to loss of information.

Good point. I was implicitly assuming a case where the interval start is aligned with the digital timer, e.g. the send pulse of a flow meter. If interval start and end are both a random times, you need two TDC measurements. Possibly performed by the same TDC unit if it can safely restarted during the main time interval.