I am reading the specs of a DAC (this one), and it says the resolution is 10 bit. Does it mean it can generate 1024 voltage levels at the sample rate which is 12 GSa/s? It sounds pretty surreal. Can it really do communications at 120 Gb/s or what would be the practical limitation?
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1The text at the linked page says "... DAC is able to sustain full-bandwidth streaming at 120 Gigabits per second". We don't even have to open a the data sheet. They didn't use the word "really", though. – Kaz May 19 '13 at 04:22
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The trick is that the data comes in over 320 lines that are individually clocked much slower. The 320 lines come in as 5 groups of 64, into 5 muxes. Each mux is 8:1, so it reduces 64 to 8. So then we have 40 bits coming out of these muxes. They go to a 4:1 that picks 10 bits. – Kaz May 19 '13 at 04:33
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"Does it mean it can generate 1024 voltage levels at the sample rate which is 12 GSa/s?" : yes, although with limits on analog bandwidth. If you ask it to generate alternating 0 / 1023 levels, for a 6GHz signal, it will be attenuated a bit as the rated output bandwidth is only 5GHz.
"Can it really do communications at 120 Gb/s or what would be the practical limitation?" : yes, via a number of parallel digital links that operate at a more reasonable 375Mbit each.
pjc50
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DAC resolution mean number of digital bits can be converted to analog signal. Yes, it means you can generate 2^10=1024 voltage levels like your thought.
The only limitation would be input rate i suppose.
Hammers
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I should have wrote like "sample rate time is low" or "sampling time is really fast". My bad. – Hammers May 19 '13 at 05:47
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"Sampling time is very high," still doesn't make any sense... or, perhaps, even incorrect. "Sampling time" is a period, so for sampling rate to be high, "sampling time" has to be low. – DrFriedParts May 19 '13 at 10:16