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Depletion-mode P-channel MOSFET

Started by Piotr Wyderski June 11, 2018
Why such a thing does not exist in nature?
I'd find several applications of such a beast.
Of a P-channel complementary to LND150, especially.

	Best regards, Piotr
On Monday, June 11, 2018 at 12:38:08 PM UTC-10, Piotr Wyderski wrote:
> Why such a thing does not exist in nature? > I'd find several applications of such a beast. > Of a P-channel complementary to LND150, especially. > > Best regards, Piotr
Can a JFET be used? They are depletion mode, commonly.
Alan Folmsbee wrote:

> Can a JFET be used? They are depletion mode, commonly.
Sometimes yes, but they don't like bipolar gate voltages and their VDS_MAX is usually much smaller than that of a MOSFET. Is there any physical reason not to produce them or is it just marketing/sales? The mankind used to produce all sort of weird semiconductor devices, UJT and tunnel diodes leading the way, but not this kind of a MOSFET. Not sure why. Best regards, Piotr
Only "several", not thousands or millions? :-)

Pch sucks in general anyway, then add to that the rarity of depletion.  You 
might as well ask for a Pch JFET (which amazingly still exist at all: you 
have your choice of J271, J176, MMBF5462 and their sisters).

Tim

-- 
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: https://www.seventransistorlabs.com/

"Piotr Wyderski" <peter.pan@neverland.mil> wrote in message 
news:pfmtkc$fb2$1@node1.news.atman.pl...
> Why such a thing does not exist in nature? > I'd find several applications of such a beast. > Of a P-channel complementary to LND150, especially. > > Best regards, Piotr
On 06/12/2018 02:32 AM, Piotr Wyderski wrote:
> Alan Folmsbee wrote: > >> Can a JFET be used? They are depletion mode, commonly. > > Sometimes yes, but they don't like bipolar gate voltages > and their VDS_MAX is usually much smaller than that of a MOSFET. > Is there any physical reason not to produce them or is it > just marketing/sales? The mankind used to produce all sort > of weird semiconductor devices, UJT and tunnel diodes leading > the way, but not this kind of a MOSFET. Not sure why. > > &nbsp;&nbsp;&nbsp;&nbsp;Best regards, Piotr
They're used sometimes in ICs, I believe, but a depletion PFET is a bit of a niche part, mostly useful with high voltage negative supplies. You can get 40V P-JFETs, but that's about the closest thing out there. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Tim Williams wrote:

> Only "several", not thousands or millions? :-)
Several is still considerably more than the number of sane UJT applications. ;-P
> Pch sucks in general anyway, then add to that the rarity of depletion. > You might as well ask for a Pch JFET (which amazingly still exist at > all: you have your choice of J271, J176, MMBF5462 and their sisters).
Use them and love them. They fit nicely e.g. in the passive MOSFET gate discharge circuits. JFETs also have the unique capability of morphing drain into source in response to the applied gate voltage, sometimes very useful. :-) Best regards, Piotr
On 06/12/18 16:23, Piotr Wyderski wrote:
> Tim Williams wrote: > >> Only "several", not thousands or millions? :-) > > Several is still considerably more than the number of sane UJT > applications. ;-P > >> Pch sucks in general anyway, then add to that the rarity of depletion. >> You might as well ask for a Pch JFET (which amazingly still exist at >> all: you have your choice of J271, J176, MMBF5462 and their sisters). > > Use them and love them. They fit nicely e.g. in the passive MOSFET gate > discharge circuits. JFETs also have the unique capability of morphing > drain into source in response to the applied gate voltage, sometimes > very useful. :-) > > &#2013266080;&#2013266080;&#2013266080;&#2013266080;Best regards, Piotr
Also super useful in polarity protection circuits for low voltage. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com