SAR ADC with serial output

[Milestone]

Hello,

I am designing a 10-bit SAR ADC and it's output chain. My SAR ADC input is 20MHz(mCLK), internally with PLL multiply to 260MHz(sCLK), with 3 sCLK to finish T/H, and 10 sCLK for conversion. Is it possible for me to use a 200MHz clock to serial output the 10-bit digital data.

I think the syncronization is a big problem for me. Or I　need to use the available 260MHz clock to output my data(output 10-bit digital data and then insert another dummy data).

Best,

Cheng

 

[jsherman]

Hi Cheng,

I'm not sure why you would want to serially output the output of the ADC, but if you really wanted to, why don't you just output the comparator's result as your serial output every clock? Really, though, I feel SAR ADC's should have a parallel output. In 10 clocks you'll have the output as you mentioned.

I guess if you really want to use a 200MHz clock to serial output the 10-bit data, you could output your results to a chain of DFFs that are clocked off of our 200MHz clock...but that seems very messy. I would strongly advise finding another method, one where you take the SAR's parallel output (or the serial output off the 260MHz clock).

Hope this helps!

 

[Milestone]

Hi jsherman,

Thanks a lot.
Actually this ADC is used in a system shown below. I first need to write the converted data into the memory and then I need to readout the converted data.

Suppose I want to readout two ADC output data(10 + 10 bit) in one ADC conversion time(50ns). In idea case I need 400MHz serilization clock, but this may give me syncronization problem(like you said, messy clock phase relationship). Or I need a 520MHz clock to output 10-bit data and 3-bit dummy data.


cheng