Hello all, For a distant future project I might want to use a Gs/s ADC. I estimate 4 bits resolution will be enough. I already checked the usual suspects (Maxim, National and e2v) but their devices are 8 bits and outside the budget (both money and power consumption). So I'm wondering if there are any other players in this field.
-- Where did you get that attitude problem? I would like to have one too!
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.
-- Where did you get that attitude problem? I would like to have one too!
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
6-bitter but that's 20 years ago. And even back then it had hardly any market.It's almost like trying to buy a three-wheeler formula 1 race car.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
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.
20MSPS isn't exactly "fast". I used such an 8-bit converter from ITT in the mid 80's. "Fast" would be >100MSPS ;-)
Possibly CA3308 that didn't quite make the cut at end test?
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
True. Ofcourse I can get away with an 8 bit (or more) ADC but I need something cheap.
-- Where did you get that attitude problem? I would like to have one too!
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.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
20 Msps at 8 bits is certainly not fast today, I get impressed at 1+ Gsps at 10 bits today. 25 years is a long time in semiconductors/ICs.
We may never know.
4 bit flash converters are embedded in PRML disk read channels. Not much use elsewhere that i know of. Damn, i have really got to get and read the basics of ATSC modulation methods. So much i want to have a handle on, and scant time.
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.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.