Wow, datasheet shows some really weird kinks in the saturation curve. Multi-level Early effect or something like that, especially on the PNP.
I've got some 2SC2878 pulls laying around somewhere. 50V collector, 25V emitter, yet good hFE. Made for switching/muting applications.
Tim
-- Seven Transistor Labs Electrical Engineering Consultation Website: http://seventransistorlabs.com
BR might be quite respectable. BR is higher the lower the doping density of the (effective) collector (the emitter when operated in reverse), but the current handling before crowding will likely be lower. ...Jim Thompson
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| James E.Thompson | mens |
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I love to cook with wine. Sometimes I even put it in the food.
That has to do with repeatedly entering breakdown of the B-E junction, degrading Beta over time... I found that out the hard way in the early '60's while designing under-hood automotive electronics. ...Jim Thompson
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| James E.Thompson | mens |
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I love to cook with wine. Sometimes I even put it in the food.
Thanks, that could come in handy.
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
"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...
It's weird, because the doping is apparently pretty similar between C and E. Yet the breakdown voltages aren't the same, so either the profile or the doping is different.
Probably, the base is also very thin (I don't have data on Early effect on these..), but it's probably also nicely interdigitated so the frequency response isn't bad (fT ~ 50MHz and up).
Tim
-- Seven Transistor Labs Electrical Engineering Consultation Website: http://seventransistorlabs.com
Even with equal doping, there would probably be 3D effects making the E field in the emitter (so labelled) higher than in the collector of the normally biased device.
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
Naaaah! The diffusions are "graded". Remember, all dopants are introduced from the _top_ surface. ...Jim Thompson
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| James E.Thompson | mens |
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I love to cook with wine. Sometimes I even put it in the food.
In planar processes, sure. Not so much with ion implant and epi. (I haven't looked up the datasheet--is that one a planar device?)
Anyway, even in a planar device the gradient will be sharper in the emitter diffusion, because it doesn't go as far. That will reduce the breakdown voltage by making the depletion layer thinner.
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
Off the top of my head I don't know of any ion-implanted _discrete_ devices. I only see it in fine-definition chips. ...Jim Thompson
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| James E.Thompson | mens |
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| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
And: The depth to E-B and the depth to B-C are almost the same, differing only by the base width. The main asymmetry of the structure is that the collector is generally (modern day processes) an epitaxial layer... uniformly doped, while the base and emitter are diffusions following Fick's equation ;-) ...Jim Thompson
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| James E.Thompson | mens |
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| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Probably so. (Having a mostly-bipolar circuit design background and an advanced-CMOS processing background, I often expect the two to be closer than they actually are.)
Maybe the MOS devices are complementary to placate the bipolar ones. ;)
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
Sno-o-o-ort ;-)
My preferred world, at least for Analog, is BiCMOS. ...Jim Thompson
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| James E.Thompson | mens |
| Analog Innovations | et |
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| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Okay, so the doping gradient would actually make the EB depletion zone thicker then, which ought to increase V_CEO vs V_CBO. What accounts for the lower breakdown voltage if the doping is really the same?
The only other things I can think of push the other way--the reverse beta is a bit lower because the effective base width is wider when depleting the graded junction. The emitter leakage is beta_R times the actual base leakage current, so even if V_CES = V_EBS, V_CEO would be less than V_EBO.
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
I'm not sure. Been a _very_ long time since I cracked open a copy of Al Phillips' book... like maybe the mid '60's, when I had his course, taught by the author himself, at Motorola SPD. (Googling him to make sure I spelled his last name properly, looks like he went on to found Western Digital ~1970) ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Posers, pretenders? :)
At least Si-PMOS isn't as bad as, say, GaAs PMOS, which as I understand it, might as well be like using toobs (N-vacuum only* ;) ).
*Some day I want a bell jar with hard-vac stuff, a bottle of hydrogen, and a proton gun, so I can try making a "P-type" tube. Guessing the performance (perveance or something equivalent, and transit time) are going to be atrocious, by approximately a factor of 2000.(Then try it with deuterium, and see if it's even worse?)
(...Then try it with D-T mix, and a really high voltage target? :D )
Tim
-- Seven Transistor Labs Electrical Engineering Consultation Website: http://seventransistorlabs.com
wrote
and
or
effect on
frequency
Well there is epitaxial layers that have been used as active region material. Not done very frequently though, ISTR there were some issues with dopant concentration control. Or maybe i am just imagining this.
?-)
No. Just confused ;-) Expitaxy is regularly used now for collector regions. I've seen some experimentation with using it for base as well, but so far I've not seen it in a commercial release. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
[about using a PNP with collector and emitter reversed]
Try oscillator/chopper transistor types, instead:
this one has a 25V rating for reverse voltage on the emitter.
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