Hi Team,
We have recently found a weird behaviour with the LMH1981 extractor chip.
We have PCB boards, which were manufactured two years ago, which extract correctly the FHV signals from a blackburst PAL reference.
Here is a capture of the H signal (falling edge) outputted by the LMH1981 (persist mode is enabled). We can see that this signal is stable in time.
We have now manufactured the exact same board (same PCB, same BoM) and the LMH1981 behaviour is not correct.
The H signal is unstable and our genlock solution is not working anymore, see capture below.
I have swapped the two LMH1981 and the problem has now disappeared on the new batch. The issue definitely follows the chip.
Have you modified the LMH1981 chips in the past months/years or do you have any explanation regarding this ?
Update: I have tested other boards from the new batch and sometimes the delay offset is smaller than the one depicted in the picture. It looks like it varies from component to component. How do you explain this behaviour?
Below you will find a capture where rising edge of H signal are not aligned (trig on rising edge using offset delay (64µs) to see the next rising edge of H signal):
Regards,
Benoit
