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BBrom's avatar
BBrom
Icon for New Contributor rankNew Contributor
7 years ago

How can I sample a signal without ADC?

Hello,​ i have little experience in FPGA programming. My situation: I am an intern and eight weeks ago i had a fpga in hand for the first time. I am using the Polmaddie 7 DevBoard with a cyclone 10...
JScho6's avatar
JScho6
Icon for Occasional Contributor rankOccasional Contributor
7 years ago

That's not entirely true. There's a (quite dirty) way by abusing the differential inputs of the FPGA. Make a resistor-ladder to generate all compare-steps, tie these to the negative input of N differential inputs. Tie all positive inputs together and feed the analogue signal into the FPGA. This is probably the cheapest flash-ADC you can build these days, but it eats up quite a few IOs, which are always scarce (at least in my designs). If you don't need too many bits of resolution, it's worth a try.

I have no personal experience with this approach, but seen it a few times on other designs. I think it's worth a try it for a resolution of 4-5 bits max.

greetings from Germany,

Jens