0
\$\begingroup\$

Say we live in a world where p-type carriers just have more mobility and therefore switches faster than n-types, so we'll favour PNP's and PMOS's. So in such circuits, we reference everything from the supply with more positive electric potential, instead of ground. What kind of system to we call those types??

I've been Googling for techniques with that sort of system, but it's coming out with nothing.

EDIT: In case anybody asks why I needed to know, I simply need to invert an analog signal from Vx voltage from ground to same voltage difference in reference from Vsupply. I'm working with MOSFETs and please don't ask me to use a Common Source or a ready made Opamp.

\$\endgroup\$
  • 2
    \$\begingroup\$ The reverse of referencing everything from ground is still referencing everything from ground. You simply change where "ground" is. \$\endgroup\$ – Ignacio Vazquez-Abrams Oct 18 '15 at 5:44
  • \$\begingroup\$ OK, sure everything's relative. In digital terms, it's now an active low system (well, not exactly, we did reverse it, but on the "digital" abstraction, not on the "electrical"). But in a broader sense (including analog), what do you call a system like that once everything else is referenced from ground? \$\endgroup\$ – Derpy_Merp Oct 18 '15 at 5:50
  • \$\begingroup\$ I mean, once we establish the less electropositive as "ground" and most of the circuit is designed around that, what do you call the complementary parts or reverse of that in analog (or broadly all of electronics) \$\endgroup\$ – Derpy_Merp Oct 18 '15 at 5:52
  • \$\begingroup\$ In circuit analysis, 'ground', or 0V, is merely a convenient reference point, chosen to, hopefully, simplify analysis. It's not defined by any physical law. But there is a huge temptation to draw the ground symbol at the southernmost point of a circuit diagram, possibly because that's where it usually appears in the classroom. \$\endgroup\$ – Chu Oct 18 '15 at 7:21
  • \$\begingroup\$ Positive earth is the name. \$\endgroup\$ – Andy aka Oct 18 '15 at 10:05
3
\$\begingroup\$

I've been Googling for techniques with that sort of system, but it's coming out with nothing.

It's called "positive earth" or "positive ground"

\$\endgroup\$
1
\$\begingroup\$

The first common transistors were PNP types (for example, the CK722).

The -15V or whatever 'plate voltage' threw the old vacuum tube guys for a loop. They were more used to voltages such as +150V.

You still have a common reference (ground) but flip polarities of supply, diodes and electrolytic capacitors.

\$\endgroup\$
  • \$\begingroup\$ Yes, germanium transistor circuits (mostly PNP) are the best example of this. \$\endgroup\$ – Brian Drummond Oct 18 '15 at 10:39

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.