NE-2 I-V Curve ??

I not only have "next", but "next-next" in the hopper.

The difference is my "next" or "next-next" will be an academic... yours will be a turd >:-} ...Jim Thompson

You're going to trust your retirement income, and your technical legacy, to an academic? That should be interesting.

I can write Spice models, but I don't as often as Jim does. As someone here has profoundly said, design is the opposite of analysis.

Some people, like Modelithics, are in the serious model-selling business. Email them and see if they have an NE-2 model.

I'm in the big time. Look at my web site.

Well-executed parts, like the simple NE-2, or a 4046 that really works, are simply advertising "teasers" to elicit requests to model nasty systems, or modeling an OpAmp to match the real world. ...Jim Thompson

1. That you know, are interested i learning, something about the modeling business and
2. Whether anyone in that biz would ever consider doing an NE-2 model.

Go ahead and ask them. They will be amused.

Agilent is a major OEM customer of ours.

I decided long ago that

I never wanted my company to get above 30 employees, and want everyone to know everyone else by first name. I set a limit on number of employees, but no limit on revenue per employee.

Everyone is polite and respectful to everyone else. Everyone is highly skilled at what they do. Everyone enjoys what they do. That implies careful hiring and some inevitable culling.

The revenue will be shared, through good pay, benefits, and bonuses for everyone.

We give customers the best support that we can, even when it doesn't make money in the short term.

We will do moderate volume, high-performance niche business (picosecond timing, precision measurement, complex controllers, photonics) and charge a lot for our products, on the basis that we sell IP, not just parts on boards.

So, we're just where I want us to be. I get to play with electronics and brainstorm with other engineers and customers, which I couldn't do if the company was a lot bigger.

Consider the signal path between our PCs. There are CPUs, DRAMS, video controllers, network adapters, modems, routers, all sorts of chips in the path. Maybe half of those chips (specifically the nanometer stuff) are fabbed using

Ever fly on a plane with a Pratt&Whitney engine?

Modeling an NE-2 sounds like negative advertising.

People like Modelithics have tons of serious frequency and time-domain (I know!) equipment, and measure the hell out of parts before they make and verify their models. If you really want to model an NE-2, you might consider actually experimenting with some.

I was just talking with a local university. They have an Agilent temperature-controlled probe station for measuring bare ICs and small packaged parts, to close the loop on fab and modeling. They don't have the capacitance module, so I think we'll buy one for them, in return for having students occasionally characterize microwave parts (diodes, transistors, MMICS) for us for time domain apps. We might meet kids who could wind up being interns and maybe employees.

I can't tell if you're being purposely coy, or if you've missed Phil's point.

Gas discharge devices like neon lamps have hysteresis: when they're on, they'll conduct at a lower voltage than their turn-on voltage.

So a simple I-V curve doesn't cut it, unless you're only trying to simulate the device in the on state, and leaving the user out to dry for figuring out turn-on and turn-off behavior.

He's just told you how clever he is.

If you can model the off-state and on-state behaviour, then at speeds slow compared with the recombination time, you can get by with a 1-bit memory telling you which model to use. It's easy to patch that up with a tanh or the equivalent to make the switch soft.

LTspice does that for you if you specify a negative hysteresis voltage.

Cheers

Phil Hobbs

Wrong. You can write a monotonic equation where the variable is current (I) and the output is voltage (V).

Watch this space >:-} ...Jim Thompson

Far cleverer than you'll ever be. ...Jim Thompson

LTspice (and many other Spice variants) use "IF" statements which converge for crap. ...Jim Thompson

Sure. But if you add them together using a switch with negative hysteresis, you'll get the nice smooth behaviour that helps convergence. LTspice uses arctan instead of tanh, which isn't as nice but usually works.

Asymptotic function theory uses the idea of neutralizer functions, which are cobbled together from erf(1/x) in the same way. They're even better theoretically since all their derivatives go to zero at the origin, so you can patch it to a straight horizontal line with no discontinuity in any order. Won't matter much for SPICE.

Cheers

Phil Hobbs

Cheers

Phil Hobbs