Low cost Gs/s ADC

Four bits may be a bit difficult, but could you make a flash converter out of fast comparators or LVDS receivers used as comparators perhaps? I think that might work reasonably for a couple of bits at this speed, but four bits may be a challenge. Also the power consumption would be a bit high.

Chris

I strongly doubt this is the way to go. Especially when build with discrete components. Variations between components, differences in delays will probably turn such a project in a world of pain. As a matter of fact, I want to use an ADC instead of a comparator.

Maybe you'll just have to pay full price then. How many do you require? If you wanted a lot of them then you might be able to negotiate a better price if they don't bond out the LSBs or something since the margin on these ADCs is likely to be huge, probably they only cost about 50c to make. I don't know of anyone selling any cheap GS/s ADCs alone, even though they are probably integrated into many high speed serial interfaces in consumer electronics so that they can do digital line equalisation. You have to pay extra if you don't want the ethernet MAC or whatever that comes on the same die with the ADC. It's a pity, because these days it would be quite easy to design this ADC on 0.18um CMOS and so dirt cheap to make, apart from the initial mask cost.

Is you application one that could get by with a video ADC (as used in flat panel monitors that have analogue RGB inputs)? Those would be cheap since they are used in a price-sensitive product, but mostly can't do more than a couple of hundred MSPS. You could try interleaving the three RGB channels with delay lines but then you are back to the world of matching pain you mentioned before. Also there is a high probability that your chosen video ADC would be discontinued in a couple of years. I would not know how much that matters because you have not disclosed your application.

Chris

Problem is, there isn't really any market to write home about for 4-bit flash converters. IIRC the lowest bit-numbers I've ever used was a fast

It's almost like trying to buy a three-wheeler formula 1 race car.

On my clock it was 25 years ago and even then 20 MSPS 8 bitters could be had. CA3308 i think they were.

Weird thing, replacement CA3306 20 MSPS 6 bit is actually available.

Possibly CA3308 that didn't quite make the cut at end test?

True. Ofcourse I can get away with an 8 bit (or more) ADC but I need something cheap.

Problem is that the markets for such converters are DSOs, ultrasound machines and scientists. Not much to write home about in terms of sales volume so chances that they ever become cheap are rather slim.

We may never know.

That's the word, "embedded". Most of this will be part of a large ASIC, data lines may be inaccessible for Nico's purpose and the chips are generally not available on the free market.