Q
I have viewed the application note "Aperture Uncertainty and ADC System
Performance", and I learned the important effect of the Aperture Uncertainty.
In AD9461 datasheet, I found there is something different between Aperture
Delay and Aperture Uncertainty.
Aperture Delay (tA)
The delay between the 50% point of the rising edge of the clock and the instant
at which the analog input is sampled.
Aperture Uncertainty (Jitter, tJ)
The sample-to-sample variation in aperture delay.
I want to use 8 pieces of AD9461 to sample 1GHz signal, so every chip's
Aperture Delay will be very important. Could the Aperture Delay be measured ?
A
Yes, if you want to use 8 pieces of AD9461, the Aperture Delay for each chip
will be different.
In fact, TA and TJ are very hard to measure, you can see that we measure TJ by
measuring the noise in our application note AN-501.
Although we don't have the TA data available in the datasheet, we know the TJ
is 60fs (typical), so the max difference of TA for every 2 pieces of AD7461
should be 60fs (typical).