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ADV7403 CVBS-525 signal shows too much jitter

Question asked by WolfgangZ on Feb 21, 2014
Latest reply on Mar 3, 2014 by WolfgangZ

We have a problem using the ADV7403 to A/D-convert a CVBS-525 signal. The Hsync output produces a jitter of up to 120ns which the following genlock (LMH1982) doesn't allow to lock. The jitter rises from power-up with about 40ns after about a minute to 100ns and after 2-3 minutes decreases back to 40ns.  When converting a CVBS-625 signal the jitter is always lower than 20ns.

 

We have produced a couple of identical A/D-converters using the application wiring and measured about half of them with the above behavior and half of them with a jitter always below 30ns.

 

We also checked the two available AnalogDevices evaluation-boards with CVBS-525: They show very different jitter values:

The EVAL_ADV734x has a jitter of about 20ns (after a 1minute delay-running-in)

The EVAL_ADV7401/3 has a jitter of up to 120ns

 

Is there any possibility to reduce the jitter adding external circuit ?

Why are there variances of the ADV7403 KSTZ-140 concerning jitter ?

 

Thanks,

Wolfgang

 

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