Odd number of bits in ADC

Question

Why is it that most ADC have even number of bit resolution like 8, 10, 12, 14 bits etc. Odd numbers are not available.

http://electronics.stackexchange.com/questions/35544/effective-number-of-bits-of-14-bit-adc?rq=1 is tangentially relevant; how many of your bits are real bits? — pjc50, Apr 20 '13 at 08:36

score 2 · Answer 1 · answered Apr 21 '13 at 00:02

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Well, actually, odd numbers ARE available. You just have to look ;)

Here's an example: ADC1112D125 : http://www.nxp.com/documents/data_sheet/ADC1112D125.pdf

answered Apr 21 '13 at 00:02

fuzzyhair2

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DarenW · Answer 2 · 2015-04-04T21:56:53.423

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In radio astronomy, the signals from pairs of antennas are multiplied then put through a very fast low-res ADC. These are rarely as much as 8 bits. Some are 3-bit, some are 2-bit, and, amazing but true, real science can be done with 1-bit ADCs. Of course, a 1-bit ADC is really no more than a simple threshold detector.

Have a look at https://science.nrao.edu/facilities/vla/docs/manuals/oss2013a/performance/samplers or https://science.nrao.edu/facilities/vla/docs/manuals/oss2013b/performance/correlator/referencemanual-all-pages

edited Apr 04 '15 at 21:56

answered Apr 21 '13 at 04:08

DarenW

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30-bit? Didn't you mean 3bit? – akaltar Apr 03 '15 at 21:31
It's the first time I've heard of 1-bit ADC http://electronics.stackexchange.com/questions/59341/what-is-a-one-bit-adc-good-for?rq=1 – phuclv Apr 05 '15 at 08:35

score 0 · Answer 3 · answered Apr 05 '15 at 07:32

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Of the 5,161 ADC's that are currently in stock at Digi-Key, 64 (about 1%) have an odd number of bits of resolution: 9, 11, 13, 15, 19 and 31 bits. So they are a rare breed.

What sets the odd-numbered ADC's apart from the others is that all 64 appear to have differential inputs. How that relates to them having a odd number of bits of resolution I don't know.

answered Apr 05 '15 at 07:32

tcrosley

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I wonder if your parametric search went astray, I found quite a few single-ended ones with odds bits for example: http://www.digikey.com/product-detail/en/AD7861APZ/AD7861APZ-ND/997890 – PeterJ Apr 05 '15 at 07:39
Note it says: Digi-Key Stock: 0. As my answer says, "Of the 5,161 ADCs that are currently in stock". Digi-Keys actually has 16,577 ADC's in their catalog, but only about 1/3 are stocked. As a matter of principle, I ignore anything Digi-Key doesn't list as in-stock. If I can't get it overnight, forget it. – tcrosley Apr 05 '15 at 07:42
Ahh yes missed that part. – PeterJ Apr 05 '15 at 07:43

Odd number of bits in ADC

3 Answers3