Well, it happened--the last fast PNP is EOL

The rabbit just keeps going... and going... and going... and going ;-) ...Jim Thompson

Point contact, Ft's measured in KHz. I think the first Touch-Tone phones used point contact transistors.

Later parts were alloy junctions, then grown junctions.

Should be only about 3:1, based on mobility. Wonder what the gotcha is? Or is it that SiGe is only NPN? ...Jim Thompson

CK760/761... my father was a Raytheon wholesaler... that's what twisted me away from architecture into electronics... toobs just didn't have any sex appeal ;-) ...Jim Thompson

ON has some PNPs up to 850 MHz. Medium fast.

I liked tubes, partly because I got them free. The first thing I designed professionally was a radiation counter that used those circular-readout gas discharge tubes, Decatrons or something. I was still in high school.

Exotic tubes were fun. Klystrons, thyratrons, PMTs, CRTs, intensifiers, sniperscope imagers, flashtubes, acorns, high voltage, weird RF jugs, like that. I wanted an xray tube but never got one.

I had an interview with a priggish guy; I told him that I liked tubes because they were harder to blow up than transistors. He sniffed "that won't do" and dismissed me. I said the same thing to the next guy and he laughed and hired me. I designed over $100 million worth of stuff for him.

You must get used to a new set of cost metrics that is completely different to that you are used to.

If it is on the qualified parts list, and it is available in less than a year, choose it. You will probably build some engineering samples and one flight sample. For the engineering samples, you can use commercial parts. When a commercial quad op amp costs $5, nobody cares. Just deciding to order ten of them costs more.

(Just kidding about you building the flight sample. I was allowed to touch it to bring it up, but there was no soldering iron in the clean room. They had quality controlled solder ladies for that.)

We had nice part decals that could accept both plastic SO-14 and the ceramic flat packs for flight. It is important that this is done according to flight board design rules, so you do not have to re-do the board layout.

The cost of qualifying a new part will dwarf the part's commercial price. Irradiation will cost a few grand, that's no problem. But you must find someone to do the paperwork. That generates work for someone higher in the hierarchy than you, and that is usually frowned upon.

I found it impossible to get a fast-ish JFET op amp for my 1:3000 pulse width stretcher. I finally gave up and designed around the problem with discrete FETs. That exploded the area of the stretcher :-( and it was ugly. Then they found they had leftover JFETs from a previous mission, _please_ , can you use this type? Aaaarghhh, JFETs are all individuals, even if they would not be of a different type.

Nobody will complain if you want 5 inductors of 470nH each. But if you want 1 each of 330n, 390n, 470n, 560n... hell will break loose. But you may not know in advance what your flight crystal looks like electrically, and the inductance needed to pull it to the right center frequency may vary.

Cheers, Gerhard

(ich bin jetzt ensthaft unterhopft!)

Yup, I am a bit familiar with that market. Now where it is going towards the private sector cost begins to matter.

Don't spoil someone's golf game by generating a lot of work 8-)

My stuff is all in the lower frequency domain, what you guys would consider jittery DC.

Come over here, I can help. I've got a Pliny the Elder clone in bottles (not many left though) and another will be dry-hopped this week, then again early next week. The Belgian Quadrupel also looks promising and clocks in above 9% but that has to rest in the secondary fermenter and then in bottles for another two months. Here is a Belgian Tripel blowing off its Kraeusen:

Dunno. Germanium hole mobility is around 2000 cm**2/V/s, which is higher than electron mobility in silicon, and dramatically higher than silicon hole mobility.

I suspect that nobody expected people to design complementary circuits that fast. I do a certain amount of gigahertz stuff, but lots of the time I'm using superfast devices in unusual ways, e.g. my fave pHEMT/SiGe NPN cascode, which I'd claim is the best wideband front end building block out there.

BTW CEL have a bunch of newish pHEMTs to replace the late lamented NE3509 etc.

Cheers

Phil Hobbs

IIRC, some car radios were implemented with tubes in RF/F stages but transistors in audio stages.

just one transistor for the output. Tubes could do the rest far cheaper.

NT

Yep. My '61 Renault Dauphine had 12V (plate) toobs for RF/Mixer/IF, then transistors for the audio. ...Jim Thompson

I've been digging around for the quickest PNPs still in production. The champs seem to be the old Fairchild Process 65 parts: MMBT3640, MMBT5771, and the discontinued PN4258. They come in at about 700 MHz peak, but they're hard to get. Digikey wants $2 for the MMBT5771!

On Semi also has the fairly weirdly named 50A02SS, which is a bigger die (400 mA vs 200), but is in plentiful supply.

The bootstrapped MMBT3906 follower worked for the customer, fortunately.

Cheers

Phil Hobbs

Jim, I hope you won't be too tired about chip design. We will be asking you very soon to start the ASIC design we discussed.

Exiting for me, first ASIC :-)

Cheers

Klaus

I hung out a bit with a giant jolly guy in Seattle who was the ICE rep there. He gave me a few of their secret chip analysies, lots of cool color micrographs. Can't remember his name just now.

Good news. We use a lot of NE3508 and NE3509 in some older products, mostly to reset timing ramps. I do that other ways for new designs.

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if you like die picture there's lots here,

Yep. Some of my ICE chip tracing analyses are on the S.E.D/Schematics Page of my website. ...Jim Thompson

Stupid idea: get a fab company to make a custom part..