input bandwidth of ADC used for HDTV application

[ashik_na]

dear all,

what is the input bandwidth of ADC used for HDTV application ?
Could you please attach the document related on that ?
I am prefering time inerleaved SAR ADC for this HDTV application having 165Mhz clock freq.

 

[qieda]

Hi,

the analog HDTV standards are defined in SMPTE_296 and SMPTE_295 standards

1080i or 1080p is defined in SMPTE_295 which says

15 Analog interface
15.1 An analog interface according to this standard
may employ either the R G B component set
or the Y Pb Pr component set
15.2 R G B signals and Y signals shall have
bandwidth nominally 60 MHz for progressive
systems and 30 MHz for interlaced systems.
15.3 Pb Pr signals shall have 0.5 the bandwidth
of the associated Y signal

720p is defined in SMPTE_296 which says

12.1 An analog interface according to this standard
may employ either the R G B component set
or the Y Pb Pr component set.
12.2 R G B and Y channels shall have a nominal
bandwidth of 30 MHz.

In this standard I did not find anything about Pb or Pr

So I think your input bandwidth should be at least above this limits. If you sample with 165MHz you normally should limit your bandwidth to fs/2. So your bandwidth should be below 165/2 MHz.

regards

 

[ashik_na]

Thank you for ur reply...
I am planning to implement this ADC for analog front end of HDTV display . Does 30MHz input frequency is required for this ADC to check its all dynamic characteristics ?

 

[qieda]

Hi,

do you plan to resample the pixel which were send by the source. Means is your sample clock aligend to the pixel clock of the source? E.g. do you have a PLL which is locked on the hsync and you use the correct feedback divider. So you do some kind of automatic sample phase adjust.
As far as I know this is the case in LCD monitor applications.
look here https://www.keil.com/dd/docs/datashts/genesis/gm2121_ds.pdf
I this case I think you need to have a undisturbed input signal and you need a high bandwidth, which should be at least your sample frequency or higher.

If this is not the case, so you just sample the analog HDTV signal I would go for a system bandwidth of e.g. 60Mhz to avoid aliasing effects. But maybe it is better to design the ADC with a high bandwidth and add an additional anti aliasing low pass filter at the input of the ADC (either internal or external).
for HDTV anti aliasing filter I found this pages
**broken link removed**
This ADC has an internal filter
https://www.analog.com/static/imported-files/data_sheets/ADV7403.pdf


regards