Talk:Field-effect transistor

Distinguishing between source/drain "terminals"

An extremely rusty electronics engineer asks: if the source and drain are both doped in the same "direction" relative to the body, what actually makes them usefully different? Is it the dopant element or concentration, the geometry (e.g. penetration depth), or something completely different? MarkMLl (talk) 20:52, 4 August 2020 (UTC)

Apparently it depends on how the transistor is manufactured. I found the answers here pretty informative: https://www.quora.com/Can-the-drain-and-source-of-a-MOSFET-be-interchangable

Cphoenix (talk) 21:19, 30 May 2022 (UTC)

Date of Lilienfeld's FET concept patent

The History section states the FET was "first patented *** in 1925", but the patent was not filed until 8 October 1926 and not issued until 28 January 1930 as shown in the approval document cited. How should the Wikipedia text be changed: to reflect the year the patent was granted or the year of filing (more interesting)... assuming the "1925" is a mistake. Myron (talk) 23:31, 12 February 2021 (UTC)

https://en.wikipedia.org/wiki/History_of_the_transistor#Origins_of_transistor_concept 176.52.34.12 (talk) 12:20, 14 April 2024 (UTC)

Are FETs source/drain symmetrical?

https://www.quora.com/Can-the-drain-and-source-of-a-MOSFET-be-interchangable/answer/Jeff-Gruszynski

This answer (which looks detailed and coherent) says that MOSFETs as used in CMOS are not symmetrical.

The "Uses" section of the article currently says "The naming convention of drain terminal and source terminal is somewhat arbitrary, as the devices are typically (but not always) built symmetrical from source to drain."

If the Quora answer is correct, then the "Uses" section should be clarified.

Cphoenix (talk) 21:16, 30 May 2022 (UTC)

I agree with Cphoenix. This statement does not seem to be correct: "The source and drain terminals can thus be interchanged in practical circuits with no change in operating characteristics or function". Aren't the differences between eg common-drain and common-source topologies due to MOSFETs being controlled by their gate-source voltage (Vgs)? In practical circuits, at least DC circuits, flipping source and drain will result in a nonworking circuit because the polarity of Vgs changes. 209.160.150.130 (talk) 21:00, 7 September 2023 (UTC)

India Education Program course assignment

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The above message was substituted from {{IEP assignment}} by PrimeBOT (talk) on 19:54, 1 February 2023 (UTC)