AVR-Chat

--- In AVR-Chat@yahoogroups.com, Robert Adsett <subscriptions@...> wrote:
> 
> The diode is inevitable in
> the MOSFET structure isn't it?

No, I don't think so.  Diodes between both source and drain and the substrate are usual, but you can get rid of those too if you don't want them (in the extreme case, using silicon-on-insulator technology).

Most of what I know about MOSFETs is from IC design.  The substrate is generally connected to ground.  N-Channel MOSFETs with their source grounded thus have the diode, but N-Channel MOSFETs with their source connected somewhere else, for example in a NAND structure, don't.  Or, rather, they have the diode but it doesn't go to the source.

I've no idea how this works with individual MOSFETs, which tend to have very complicated structure these days.  I would absolutely not make any assumptions that are not backed up by the manufacturer's data sheet.

Graham.