I just made my prototype oscilloscope amplifier probe using these. The next best devices I could find are ON's MMBTH81 ft=600MHz(min) @ 1/8 speed. How else is one suppose to provide drive to the positive rail !!!
Is this the first sign of the great technological unwinding of humanity.
No, we're well down the curve. It was IBM's discontinuing OS/2 that started it. ;)
You used to be able to get 8.5 GHz PNPs (I have 100 or so of them).
Cheers
Phil Hobbs
The early days of analog IC design was all NPNs. There were some truly awful all-NPN opamps.
Back to the future, I suppose.
I spent most of my adulthood perfecting a pulse generator output stage circuit. When I finally got it almost right, the critical PNPs went EOL.
And as noted here, a billion-dollar product line has stopped because a
50 cent NEC transistor went EOL. That's either tragic or hilarious.-- John Larkin Highland Technology, Inc lunatic fringe electronics
Which ones? Even the 709 had lateral PNPs.
The LM318 was probably the apogee. Of course it also had lateral PNPs in it, but to get it to go fast you had to bypass the level shifters by putting capacitors to the Vos adjust pins.
National had an app note where they tied both inputs to VEE and used a JFET matched pair with its collectors going to the Vos pins.
Both, depending on whether you're considering the folks that are going to get laid off or the ones whose heads are exploding (but will probably keep their jobs).
There are workarounds, such as real vs. folded cascodes and current source pullups with real or simulated inductors in series, but they all cost headroom, current, complexity, performance, or (usually) all four.
OTOH that all-NPN cascoded White follower circuit I posted last year works much better than the PNP wraparound, so all is not necessarily lost. ;)
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
Ah, OK, the uA702 was all-NPN, and it was pretty horrible.
The old TI datasheet for their version has a schematic:
The tail current generator is interesting.
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
GE made an opamp that used a zener internally as a level shifter. It made a nice noise generator.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
ething.
I realize this is very stale.
Anyway, I had a call for a JFET recently. The J232 and perhaps 2N4116A look ed okay for what I needed. Only Interfet makes the J232 anymore, and I've n ever had experience with them.
OnSemi still has legacy stuff but has EOL'd some things. It seems that Cent ral Semi, Linear Systems, and Interfet live on legacy, and even welcome it. Central Semi and Linear Systems do bipolar parts, unlike Interfet. It made me think of this old thread. (I don't know the fabs they use.)
I haven't really done much with Central Semi & Linear Systems, so I don't k now what they are capable of. Did you consider a query to them on the BFT92 ?
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