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Question asked by emanuele.cardani on Nov 7, 2011
Latest reply on Nov 7, 2011 by GuenterL

I need to sample RGB analog video coming from ADV7393. To perform this task I thought to use an ADV7403.

Is this a good choice?

Reading the AD manual I noticed this (6.4.1) paragraph:


"When sampling an RGB graphics signal, as generated from PCs etc., the analogue input waveform is assumed to be a full bandwidth graphics signal that is sub-sampled. The signal will not have gone through a reconstruction filter but will show discrete levels and transitions in between. In this mode of operation, the ADCs must sample at the flat portions of the waveform and avoid the transition period.
To cater for this, a DLL has been implemented in the analogue front end (see Figure 13). This DLL divides the TLLC sampling clock into 32 evenly spaced phases. The DLL_PH[4:0] signal can be used to set the ADC sampling point to any of those phases."

As I need to sample standard definition RGB video (i.e. 576i) I was wondering if the sample phase would matter even in case as the video bandwidth is supposed to be far less than PC graphic.

Is in this case the optimum DLL tuning mandatory?

I also noticed that a “Backend IC” is supposed to perform this task. Can you suggest me which IC is supposed to do that?



Emanuele Cardani