I sometimes encounter that ADCs, DACs, PLLs, DC-DC converters and oscillators are called mixed-signal but sometimes they are grouped under the category of analog.
Is there a consensus about that?
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\$\begingroup\$ There is something analogue about all of them. Personally speaking, grouping MOSFETs, BJTs, IGBTs, Triacs, JFETs, DIACs, integrated circuits, zeners, schottky diodes, regular diodes and suchlike under the heading "semiconductors" is an equally useless categorization. \$\endgroup\$– Andy akaCommented May 20, 2020 at 12:08
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2 Answers
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Grouping is usually done for the convenience of someone that is trying to sort a large list of varied items into smaller lists that are easier to navigate. Unfortunately one persons idea of what belongs in what list is often questionable just like in the case of "analog" versus "mixed signal" 1.
I have searched many times on a manufacturer or vendor web site for some type of part and not finding it by scanning through some category list and not finding what I wanted. So rather than trying to find that way I have resorted using web sites that have exceptional search features (both Digikey and Mouser are pretty good; some manufacturer sites are really bad). This way I can input parameters related to what I want and let the search engine scan the whole database instead of a category focus.
A simple example is if I am looking for capacitors on Mouser I would enter something like "330uF 16V" into their top search bar.
1 - I am reminded of the old saying that "everything is analog" in the big picture.
answered May 20, 2020 at 12:21
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\$\begingroup\$ Does IEEE have no clear definition? \$\endgroup\$– cm64Commented May 20, 2020 at 12:31
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1\$\begingroup\$ it's not the sort of thing that needs a definition. \$\endgroup\$– Neil_UKCommented May 20, 2020 at 12:58
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\$\begingroup\$ @cm64 Why do you need a specific definition for what is just a marketing term? Things are what they are. Many technical sound terms, especially classifications, are just meant to express a general idea, not a specific one, nor is everything mutually exclusive. \$\endgroup\$– DKNguyenCommented May 20, 2020 at 15:25
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\$\begingroup\$ IEEE Std 24765 does define analog as "pertaining to continuously variable physical quantities or to data presented in a continuous form, as well as to processes and functional units that use the data". The term "mixed-signal" is not defined or used in that standard. \$\endgroup\$ Commented May 20, 2020 at 16:53
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Ultimately, everything is analog. The differences are in application.
- digital: deals with logic, uses binary voltage levels (limited case of analog)
- analog: deals with signals, uses continuous voltage levels
- mixed-signal: the boundary between analog signals and digital logic, using a mixture of both
So a PLL will have a VCO (analog) plus phase detect and dividers (digital), so it’s mixed-signal.
answered May 20, 2020 at 15:54