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From: Tim Williams on 11 Aug 2010 17:06
"markp" <map.nospam(a)f2s.com> wrote in message
news:8cgekjFubtU1(a)mid.individual.net...
> You mean PMOS as in P-channel MOSFET? Is that enhancement mode? There
> are certainly quite a few P channel enhancement mode MOSFETs around, I
> tend to
> use the BSS84 as a P-channel equivalent of the 2N7002. They are pretty
> close
> in price, certainly not significantly more, and multi-sourced.

I didn't see BSS84 on Mouser's search. Ha, figures, the cheapest entry
doesn't have any characteristics:
http://www.mouser.com/ProductDetail/NXP-Semiconductors/BSS84215/?qs=sGAEpiMZZMutXGli8Ay4kDE4J8KCiPsFBEpkUtYt8m4%3d
Still 11 cents in 100s, whereas 2N7002s (that show up in the list) are 5c.
Not "significantly" more, but it's over a factor of two anyway.

I suppose I could try arguing "multi-source" as well, since there's only a
few that are near that price range AND in stock (to bend the meaning of
"source" to mean "cheapest parts only"..). Sure, there are lots in stock,
but they seem to average $0.30 in hundreds, which is just silly for an
SOT-23.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms


From: Phil Hobbs on 11 Aug 2010 18:04
Tim Williams wrote:
> "John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in
> message news:gcq566pvub8jtqbtirn8oiu6s0rbt5ge1s(a)4ax.com...
>> Like GaAs DCFL, the GigaLogic stuff? That was depletion load, I think,
>> like old-old NMOS stuff. Power hog.
>
> Yuck, GaAs logic. It sounds like a good idea, until your signal has to
> change back.
>
> Silicon PMOS aren't terrible, good enough to make high speed CMOS with.
> They're almost impossible to find discrete though. I haven't been able to
> find a P type 2N7002 for the same price.
>
> The suckiness of PFETs is directly related to the bandgap. Silicon is
> moderate, so PFETs are okay. GaAs and GaN make shitty PFETs. I can only
> imagine how poorly SiC and diamond PFETs will work, when they come along.
> I suppose they may already exist in the laboratory, I don't know.
> Curiously, this seems to imply that Ge-CMOS would be quite nice indeed,
> but the leakage is something else.
>
> Tim
>

The old argument against Ge was that it doesn't have a good oxide--GeO2
is water soluble. Nowadays that isn't such a big worry, since high
performance FETs don't use SiO2 gate insulation anymore--at least not in
logic.

Do you have a reference for the PFET performance vs bandgap? InGaAs has
a much lower bandgap than GaAs, but its hole mobility is similar.

(Not busting your chops--it's an interesting correlation if true.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net
From: John Larkin on 11 Aug 2010 19:05
On Wed, 11 Aug 2010 16:06:26 -0500, "Tim Williams"
<tmoranwms(a)charter.net> wrote:

>"markp" <map.nospam(a)f2s.com> wrote in message
>news:8cgekjFubtU1(a)mid.individual.net...
>> You mean PMOS as in P-channel MOSFET? Is that enhancement mode? There
>> are certainly quite a few P channel enhancement mode MOSFETs around, I
>> tend to
>> use the BSS84 as a P-channel equivalent of the 2N7002. They are pretty
>> close
>> in price, certainly not significantly more, and multi-sourced.
>
>I didn't see BSS84 on Mouser's search. Ha, figures, the cheapest entry
>doesn't have any characteristics:
>http://www.mouser.com/ProductDetail/NXP-Semiconductors/BSS84215/?qs=sGAEpiMZZMutXGli8Ay4kDE4J8KCiPsFBEpkUtYt8m4%3d
>Still 11 cents in 100s, whereas 2N7002s (that show up in the list) are 5c.
>Not "significantly" more, but it's over a factor of two anyway.
>
>I suppose I could try arguing "multi-source" as well, since there's only a
>few that are near that price range AND in stock (to bend the meaning of
>"source" to mean "cheapest parts only"..). Sure, there are lots in stock,
>but they seem to average $0.30 in hundreds, which is just silly for an
>SOT-23.
>
>Tim

FDV302 is 5 cents by the reel. The n-ch version, FDV301, is 4.8 cents.
Both are logic-level SOT23 mosfets, nice little parts, usable with 3.3
volt drive.

John



From: markp on 11 Aug 2010 19:38

"Tim Williams" <tmoranwms(a)charter.net> wrote in message
news:nhE8o.64614$4B7.49357(a)newsfe16.iad...
> "markp" <map.nospam(a)f2s.com> wrote in message
> news:8cgekjFubtU1(a)mid.individual.net...
>> You mean PMOS as in P-channel MOSFET? Is that enhancement mode? There are
>> certainly quite a few P channel enhancement mode MOSFETs around, I tend
>> to
>> use the BSS84 as a P-channel equivalent of the 2N7002. They are pretty
>> close
>> in price, certainly not significantly more, and multi-sourced.
>
> I didn't see BSS84 on Mouser's search. Ha, figures, the cheapest entry
> doesn't have any characteristics:
> http://www.mouser.com/ProductDetail/NXP-Semiconductors/BSS84215/?qs=sGAEpiMZZMutXGli8Ay4kDE4J8KCiPsFBEpkUtYt8m4%3d
> Still 11 cents in 100s, whereas 2N7002s (that show up in the list) are 5c.
> Not "significantly" more, but it's over a factor of two anyway.
>
> I suppose I could try arguing "multi-source" as well, since there's only a
> few that are near that price range AND in stock (to bend the meaning of
> "source" to mean "cheapest parts only"..). Sure, there are lots in stock,
> but they seem to average $0.30 in hundreds, which is just silly for an
> SOT-23.
>
> Tim
>

You can get BSS84 for somewhat less than 11c:
http://gb.mouser.com/Search/Refine.aspx?Keyword=BSS84
BSS84LT1G showing as 4.3p (UK prices) for 100 off.

Also in Newark (www.newark.com) Fairchild BSS84 going for 6c for 100 off.
NXP version for 11c.

Mark.






From: markp on 11 Aug 2010 19:46

"markp" <map.nospam(a)f2s.com> wrote in message
news:8cgqjoFqhU1(a)mid.individual.net...
>
> "Tim Williams" <tmoranwms(a)charter.net> wrote in message
> news:nhE8o.64614$4B7.49357(a)newsfe16.iad...
>> "markp" <map.nospam(a)f2s.com> wrote in message
>> news:8cgekjFubtU1(a)mid.individual.net...
>>> You mean PMOS as in P-channel MOSFET? Is that enhancement mode? There
>>> are certainly quite a few P channel enhancement mode MOSFETs around, I
>>> tend to
>>> use the BSS84 as a P-channel equivalent of the 2N7002. They are pretty
>>> close
>>> in price, certainly not significantly more, and multi-sourced.
>>
>> I didn't see BSS84 on Mouser's search. Ha, figures, the cheapest entry
>> doesn't have any characteristics:
>> http://www.mouser.com/ProductDetail/NXP-Semiconductors/BSS84215/?qs=sGAEpiMZZMutXGli8Ay4kDE4J8KCiPsFBEpkUtYt8m4%3d
>> Still 11 cents in 100s, whereas 2N7002s (that show up in the list) are
>> 5c. Not "significantly" more, but it's over a factor of two anyway.
>>
>> I suppose I could try arguing "multi-source" as well, since there's only
>> a few that are near that price range AND in stock (to bend the meaning of
>> "source" to mean "cheapest parts only"..). Sure, there are lots in
>> stock, but they seem to average $0.30 in hundreds, which is just silly
>> for an SOT-23.
>>
>> Tim
>>
>
> You can get BSS84 for somewhat less than 11c:
> http://gb.mouser.com/Search/Refine.aspx?Keyword=BSS84
> BSS84LT1G showing as 4.3p (UK prices) for 100 off.
>
> Also in Newark (www.newark.com) Fairchild BSS84 going for 6c for 100 off.
> NXP version for 11c.
>
> Mark.
>

Oops, some of those not in stock. This always happens when we come out of
recession. The reason for non-stock is allocation problems, the prices of
anything left in stock might go up accordingly. Still it looks like BSS84 is
roughly the same as 2N7002 if they were.

Mark.


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