Curve tracers

Methinks you're applying apples thinking to oranges. If you take a measurement at a fixed operating point, whether it be DC or pulsed, your average junction temperature is likely to be different from what it would be in an analog curve tracer like the 576. All those measurement points are not likely to line up on exactly the same line you'd see with an analog plot. Nothing wrong with that. If you want data at a particular operating point, that's the way to go. If you want a curve tracer, like it says in the subject line, you may not see what you expect.

He must be on the north shore in Suffolk county. It was like a 3rd world country out there on Monday. 33" somewhere, I think Farmingville. We still have people MIA at work, snowed in. The plows never got down their streets. I'm further east, still got 19", but like Phil only took an hour or two to clean up.

Cheers

He lives in north of East Setauket, I think that's 6mi north of Farmingville.

--
Regards, Joerg 

http://www.analogconsultants.com/

It rained here yesterday.

Low 60's daytime... but it did go down to freezing last night... the swimming pool pump came on automatically to prevent pipe freezing ;-) ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     | 
| Analog Innovations, Inc.                         |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| Phoenix, Arizona  85048    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.

Yea, abouts. That?s up by Port Jefferson, on the north shore. They had like 8" Friday evening, where the south shore was just changing over from rain to snow. It was heavy stuff. I heard they had Snow Blowers clearing the 495 expressway. and I seen the Snow Blowers clearing the shoulders on the parkways this evening. Getting ready for the next two storms, 5" Wednesday and More to come on the weekend. Too bad theres no ski resorts here ;(

Cheers

generate

and

beta,

A wall wart or completely supplied by the few watts available from USB would probable do for your needs, Phil. Many of us would need at least a line cord brick (ala laptop) to reach enough of the higher voltages and currents (often in pulse mode, but that is ok too).

Sounds like a great idea for a group project, many could contribute and we could put in Creative Commons afterwards. Or not. Just a thought.

With an ARM to drive the circuitry and ship the data fast, plus the PC to reform the data into SPICE friendly forms we could generate good models. If we test say 2 dozen parts each from several manufacturers we could make models that can be Monte Carlo tested effectively (because we know the distribution of the parameters). NOT saying it would be fast.

?-)

TransAm

Hey it may be a bit basic, but it works. It is an adequate approach for very simple rate monotonic schedulers but the linked list time will start to hurt if things get complicated and crowded schedule wise. He needs to separate the switcher from the task manager. Then schedule time for the task manger as a task.

TransAm

so

out

Likely they would also have to plough 1/2 mile or more street just to get to his driveway.

?-)

pdf

That is a nice old time experimenters supply. Are they available?

p3984.m1423.l2649

beta,

I use big honking caps or car batteries for that.

That is why they added pulse mode measurements, so you could see it both ways.

you

Even then.

Agreed on the range switching issues. Maybe just use different test equipment.

?-)

generate

beta,

day.

you

Oh foo, the fixturing for RF devices can get really weird and expensive. Those will be on you if we get together and create a USB curve tracer.

?-)

I'll have to find the box, but I have 25 NOS out in the shop. I'll let you know when i find them.

The problem with a lot of (most) RF devices is their terrible DC characterization. Like, no DC curves at all. The s-params give you a rough idea of the high-speed behavior.

RF data sheets often say to just adjust the bias until it works. The specified breakdown voltage specs are not useful, because sometimes they assume, without saying so, that the drain voltage can swing to multiples of the supply voltage, and factor that in. Parts spec'd at 6 volts can cheerfully avalanche at 25. A detector diode might be spec'd a 2 volts reverse, woth no curves at all, because they figure that's all a detector user needs to know.

--

John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom timing and laser controllers 
Photonics and fiberoptic TTL data links 
VME  analog, thermocouple, LVDT, synchro, tachometer 
Multichannel arbitrary waveform generators

It isn't really a multitasking OS, just a way of scheduling stuff for future reference, e.g. looking after a delta-sigma ADC that needs a

3-million clock reset interval. For now the list elements consist of a time stamp, a pointer to a flag variable, and the tail pointer. The systick interrupt just looks at the next thing in the list to see if the time stamp matches, and if so, pops the element, sets the flag, and checks the next one in case it has the same time stamp.

All the work is done by functions called from the housekeeping loop. None of them takes enough time that it needs to be preempted--it's quick stuff like setting up a DMA to redraw the screen, taking a data point, sending a character to the USB serial port, that sort of stuff. (I've been doing embedded stuff off and on for a dozen or so years, but I'm nobody's idea of an expert at it.)

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 USA 
+1 845 480 2058 

hobbs at electrooptical dot net 
http://electrooptical.net

idea

voltage,

because

I'm normally working down on the low frequency end anyway, e.g. a 100 MHz biochip front end using 14-GHz pHEMTs and 40-GHz bipolars, so simple concepts like C_JC and R_BB' still work OK. Boontons rule!

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 USA 
+1 845 480 2058 

hobbs at electrooptical dot net 
http://electrooptical.net

Thanks. I agree, it seems like a vast wasteland.

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 USA 
+1 845 480 2058 

hobbs at electrooptical dot net 
http://electrooptical.net

idea

specified

without

voltage,

because

Right. You have to make your own curves, like C-vs-V. That's why a USB curve tracer should measure capacitances, too.

Heck, somebody here with a curve tracer and a Booonton could set up a garage operation to characterize parts for a fee. Modelithics does that for big bucks.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation

you

idea

specified

without

voltage,

A

because

Have you measured the leakage of the Boonton's biasing system? Maybe one could just hang a little board on the back of one, and do it that way.

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 USA 
+1 845 480 2058 

hobbs at electrooptical dot net 
http://electrooptical.net

you

idea

specified

without

voltage,

A

because

Good idea. Design the USB curve tracer to run through a Boonton 72 to get the capacitances. The Boonton has an analog output on the back. But it would be more fun to do it ourselves.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation