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Message |
Winfield Hill
Guest
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 Posted:
Sun Dec 11, 2005 5:35 pm Post subject:
Re: the ultimate PNP transistor |
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Jim Thompson wrote...
| Quote: |
Win, Did you really invent "she..esh"?
|
Of course not. IIRC, my dad used to use the term, so it must
go way back. I imagine it's a polite way of saying shit.
--
Thanks,
- Win
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Winfield Hill
Guest
|
| Posted:
Sun Dec 11, 2005 5:35 pm Post subject:
Re: the ultimate PNP transistor |
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Jim Thompson wrote...
| Quote: | Winfield Hill wrote:
clicliclic@freenet.de wrote...
... I have tried the BF324 and BF450 (both Philips) with
reasonable results.
The limiting factor here indeed appears to be the collector-base
capacitance: measured zero-bias values are ~3pF and ~2pF, respectively.
Fast PNP switching transistors like the 700MHz 2N5771 are not
automatically better suited.
That's no surprise, with the 2n5771's relatively high capacitances,
3pF, compared a much lower 0.3 and 0.55pF at 5-10V reverse bias.
So, what is the ultimate PNP transistor for this type of application?
Is something like the 5GHz BFT52 (Ccb ~ 1pF according to the Philips
Spice model) still available in a through-hole package?
About 0.7pF at sensible reverse bias according to the datasheets,
just a bit higher than you've been using. But there are plenty of
lower-capacitance smaller-die-size choices if that's important.
Operation with E and C interchanged may also be considered if the
reverse beta exceeds five.
Sheesh!
DOUBLE-SHEEEEESH! Such amateurs ;-)
|
What a minute. First I invent Sheesh!, then you go and invent
DOUBLE-SHEEEEESH!? Sheesh!
--
Thanks,
- Win |
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Jim Thompson
Guest
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| Posted:
Sun Dec 11, 2005 5:35 pm Post subject:
Re: the ultimate PNP transistor |
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On 11 Dec 2005 07:32:15 -0800, Winfield Hill
<Winfield_member@newsguy.com> wrote:
| Quote: | Jim Thompson wrote...
Winfield Hill wrote:
clicliclic@freenet.de wrote...
... I have tried the BF324 and BF450 (both Philips) with
reasonable results.
The limiting factor here indeed appears to be the collector-base
capacitance: measured zero-bias values are ~3pF and ~2pF, respectively.
Fast PNP switching transistors like the 700MHz 2N5771 are not
automatically better suited.
That's no surprise, with the 2n5771's relatively high capacitances,
3pF, compared a much lower 0.3 and 0.55pF at 5-10V reverse bias.
So, what is the ultimate PNP transistor for this type of application?
Is something like the 5GHz BFT52 (Ccb ~ 1pF according to the Philips
Spice model) still available in a through-hole package?
About 0.7pF at sensible reverse bias according to the datasheets,
just a bit higher than you've been using. But there are plenty of
lower-capacitance smaller-die-size choices if that's important.
Operation with E and C interchanged may also be considered if the
reverse beta exceeds five.
Sheesh!
DOUBLE-SHEEEEESH! Such amateurs ;-)
What a minute. First I invent Sheesh!, then you go and invent
DOUBLE-SHEEEEESH!? Sheesh!
|
Win, Did you really invent "she..esh"?
I've had it in my spelling checker... many different lengths of
e-strings, for a very very long time ;-)
Same with "Bwahahaha..haha", no matter the number of rat-a-tats, it
always passes spelling check ;-)
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
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Winfield Hill
Guest
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| Posted:
Sun Dec 11, 2005 11:39 pm Post subject:
Re: the ultimate PNP transistor |
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Spehro Pefhany wrote...
| Quote: |
Winfield Hill wrote:
Jim Thompson wrote...
Win, Did you really invent "she..esh"?
Of course not. IIRC, my dad used to use the term, so it must
go way back. I imagine it's a polite way of saying shit.
Cripes, no. The American Heritage dictionary says it's an
alteration of "Jesus".
|
What, a religious swear word, taking the Lord's name in vain?
Shit!
--
Thanks,
- Win |
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Frank Bemelman
Guest
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| Posted:
Mon Dec 12, 2005 12:19 am Post subject:
Re: the ultimate PNP transistor |
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"Winfield Hill" <Winfield_member@newsguy.com> schreef in bericht
news:dnhke40r4b@drn.newsguy.com...
| Quote: | Jim Thompson wrote...
Win, Did you really invent "she..esh"?
Of course not. IIRC, my dad used to use the term, so it must
go way back. I imagine it's a polite way of saying shit.
|
I actually thought it was another form of "Jesus". Like "Holy Mackarel"
or something.
--
Thanks, Frank.
(remove 'q' and '.invalid' when replying by email) |
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Frank Bemelman
Guest
|
| Posted:
Mon Dec 12, 2005 12:20 am Post subject:
Re: the ultimate PNP transistor |
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"Jim Thompson" <To-Email-Use-The-Envelope-Icon@My-Web-Site.com> schreef in
bericht news:ajmop1p61tlvdo9ic6kmm202ve5d2le200@4ax.com...
| Quote: | On 11 Dec 2005 08:34:12 -0800, Winfield Hill
Winfield_member@newsguy.com> wrote:
Jim Thompson wrote...
Win, Did you really invent "she..esh"?
Of course not. IIRC, my dad used to use the term, so it must
go way back. I imagine it's a polite way of saying shit.
Come to think of it, I _do_ remember my mother saying "sheeesh" ;-)
|
When she gave birth to you, and many occasions after that, no doubt.
--
Thanks, Frank.
(remove 'q' and '.invalid' when replying by email) |
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Jim Thompson
Guest
|
| Posted:
Mon Dec 12, 2005 12:25 am Post subject:
Re: the ultimate PNP transistor |
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On Sun, 11 Dec 2005 13:25:44 -0500, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:
| Quote: | On 11 Dec 2005 09:39:48 -0800, the renowned Winfield Hill
Winfield_member@newsguy.com> wrote:
Spehro Pefhany wrote...
Winfield Hill wrote:
Jim Thompson wrote...
Win, Did you really invent "she..esh"?
Of course not. IIRC, my dad used to use the term, so it must
go way back. I imagine it's a polite way of saying shit.
Cripes, no. The American Heritage dictionary says it's an
alteration of "Jesus".
What, a religious swear word, taking the Lord's name in vain?
Shit!
Shoot, you're right.
Best regards,
Spehro Pefhany
|
Probably derived from Jeeez.. --> Jeesh --> Sheesh
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food. |
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Spehro Pefhany
Guest
|
| Posted:
Mon Dec 12, 2005 12:25 am Post subject:
Re: the ultimate PNP transistor |
|
|
On 11 Dec 2005 09:39:48 -0800, the renowned Winfield Hill
<Winfield_member@newsguy.com> wrote:
| Quote: | Spehro Pefhany wrote...
Winfield Hill wrote:
Jim Thompson wrote...
Win, Did you really invent "she..esh"?
Of course not. IIRC, my dad used to use the term, so it must
go way back. I imagine it's a polite way of saying shit.
Cripes, no. The American Heritage dictionary says it's an
alteration of "Jesus".
What, a religious swear word, taking the Lord's name in vain?
Shit!
|
Shoot, you're right.
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com |
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Guest
|
| Posted:
Mon Dec 12, 2005 1:35 am Post subject:
Re: the ultimate PNP transistor |
|
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Winfield Hill schrieb:
| Quote: | clicliclic@freenet.de wrote...
... I have tried the BF324 and BF450 (both Philips) with
reasonable results.
The limiting factor here indeed appears to be the collector-base
capacitance: measured zero-bias values are ~3pF and ~2pF, respectively.
Fast PNP switching transistors like the 700MHz 2N5771 are not
automatically better suited.
That's no surprise, with the 2n5771's relatively high capacitances,
3pF, compared a much lower 0.3 and 0.55pF at 5-10V reverse bias.
So, what is the ultimate PNP transistor for this type of application?
Is something like the 5GHz BFT52 (Ccb ~ 1pF according to the Philips
Spice model) still available in a through-hole package?
About 0.7pF at sensible reverse bias according to the datasheets,
just a bit higher than you've been using. But there are plenty of
lower-capacitance smaller-die-size choices if that's important.
|
There may be plenty (readily available? in a through-hole package?),
but judging from the replies so far there isn't plenty of knowledge
about them and their uses ... Dunno if that makes it important ...
| Quote: |
Operation with E and C interchanged may also be considered if the
reverse beta exceeds five.
Sheesh!
|
Please take your time to recover from this shock. It's not _that_
important ...
Martin.
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