Hello.
I purchased this device because the TDC7200 is described as having a timing precision as low as 50 ps (approximately). Indeed, I was able to observe down to 75 ps standard deviations for measurement times around 1 us. However, when I switched to measurement mode 2 and increased my measured time interval to several milliseconds, my standard deviation of measurements went way up. I bought a second TDC7200EVM to separate variation in my pulse generator from uncertainty in the measured time (i.e. measure the same time interval with both devices, then ideally the standard deviation of the difference should be near the true uncertainty of the device). After doing this I found that the uncertainty in the TDC devices was a few nanoseconds; it had indeed risen well beyond the expected level of precision. Of course, we are shown in Figure 17 in the datasheet that the precision may rise up to 250 ps when using measurement mode 1 for a lengthy time interval. However, I had used measurement mode 2, and my standard deviations were still 10 times that. Does this device simply fail to perform at the highest time interval measurements? If so, is there a better TDC device you could refer me to?
To summarize, I need to measure time intervals around 5 ms with a precision near 50 ps. Can the TDC7200 do this? If not, I would appreciate being pointed to a device which can.
Thanks for any and all assistance.
~Dan
