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Tim Williams[_3_] Tim Williams[_3_] is offline
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Default Thermometer Code Chip

"John Larkin" wrote in message
...
Classic flash ADCs used 2^n comparators and a resistor string in the
front end. The resulting (say, 256 bit) thermomometer code was then
mapped into binary. I think somebody did that at 10 bits, 1024
comparators.

Nowadays people tend to do cleverer things.


Are they still de rigeur for the bleedingest of edges in the Hittite and
etc. catalogs?

Pipelined SAR has certainly come a long way since the olden days.

I've seen an oddly large number of DACs that claim to do this, even for 12
bits. Seems odd that they'd succeed in using that many resistors and MOS
gates. Could well be that they're doing some R-2R action regardless,
maybe even a bit of each (an R-2R chain is binary, but an R-R-..-2R-2R-..
network would work for any base; the classic resistor decade box being
such a case, for N = 10).

Tim

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