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DDC112: DDC 200MSPS read 4 Photodiodes Currents

Calex36
Intellectual 2295 points
Part Number: DDC112


Hi, 

I am looking for an ADC with current inputs to read 4 Photodiode currents and convert to digital outputs simultaneously. 

The digital output going to PC via USB

My conversion speed requirement is >=200MSPS,  

I found the DDC112 that seems to tick all the boxes but the conversion speed, unless it does? 

Are there any other DDC's you could recommend?  

Or am i better off TIA -> High speed ADC for this conversion speed requirement. 

If so what would you recommend in that case also. 

Your help is much appreciated 

regards 

Calex

  • 0
    TI__Intellectual 2295 points

    Hi, 

    From looking into this i think the TIA -> FDA -> ADC is better suited to conversion speed requirements here, 

    similar to as shown in this TI design but with faster ADC 

    What advantages except a lower chip count would and possibly resolution would a DDC bring to me in this application?  

    A response would be appreciated 

    Calex

  • 0 in reply to Calex36
    TI__Expert 4680 points

    Hi Calex,

    You are totally right. I imagine that if you are planning to use a 200MSPS ADC is because your signal BW is quite large. The DDCs are intended for low frequency signals (KHz). So, they would basically not work for your application. As you said, their use is for applications that require a much higher dynamic range and integration. (To be precise, your application may also require that dynamic range and integration but there is nothing out there that can do 20b/200MSPS so you are forced to give up stuff/use a more discrete solution...)

    So, as you are doing, I would look into discrete TIAs and ADCs. You may want to post for those folks on the forum if you need help selecting parts. I'll see if I can get help from someone to fwd this post to them too...

    Best regards,

    Edu