HOW to compare two phase width in same signal wire?

[xworld2008]

HOW to compare two phase width in same signal wire?（difference is ps level）？

_____________|—--|___________________|--------|_____________
--45ps-- ----50ps--------


any one have idea??

Thanks,

 

[crutschow]

Not sure what you want to measure. What is phase width? What is ps level?

 

[xworld2008]

Sorry .. Should be pulse width. I want to measure the different of to pulse for a signal.

 

[crutschow]

Can you use a high speed oscilloscope?

 

[xworld2008]

Can not.. we want to measure it using circuit design..

 

[crutschow]

Measuring such short pulse widths is not easy. It typically requires some very high speed digital circuits. Not something for a novice.

 

[xworld2008]

could you suggest which high speed digital circuit can be used to do it?

 

[keith1200rs]

A TDC chip would only get you down to around 20ps resolution so I suspect you need a custom device or custom circuitry. The TDC principles can possibly be used but you need even higher resolution. I have used Guide Technology boards in the past - they get down to 8ps. although the continuous ones get down to 2ps with averaging. This is fairly serious design to do that from scratch.

Keith

 

[xworld2008]

A TDC chip would only get you down to around 20ps resolution so I suspect you need a custom device or custom circuitry. The TDC principles can possibly be used but you need even higher resolution. I have used Guide Technology boards in the past - they get down to 8ps. although the continuous ones get down to 2ps with averaging. This is fairly serious design to do that from scratch.

Keith

Hi Keith,

Thanks.. now i need a circuit to do it.

 

[keith1200rs]

Search IEEE papers for TDCs (Time to Digital Converters) - it should give you some ideas about the techniques to use. Also, it is worthwhile searching for theses at the University of Oulu. They have done a lot of research for Noptel on laser rangefinders and as they were PhD or MSc theses the information is freely available. https://www.oulu.fi/english/

Keith