On Thu, 14 Feb 2013 08:04:35 -0500, Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> wrote:> >>>>Sure, I'm in. Do you think it might actually sell? >>>> >>> >>>Well, some for sure. Ten a year? 200?=20 >>> >>>Time to start scribbling. >> >>We might make two or more models. Some dependency on price, features, =and>>performance for sales outside this ng. Within the ng we could probably >>make and deploy one to two dozen. Then with real world experience i >>think we could do a better job of selling it outside. >> >>?-) > >How practical do you think it would it be to add temperature >characterization? I'd be interested in that.=20 > >Doable but may take some special customization. I have used such equipment, and it wasn't cheap. Thermal boundaries are a big issue. Controlling DUT temperature without upsetting (or causing unwanted gradients within) the tester can get very challenging. It is still = easier to heat a DUT than to cool it below room temp (air driers or dry gasses are required very quickly). ?-)
Curve tracers
Started by ●February 11, 2013
Reply by ●February 16, 20132013-02-16
Reply by ●February 16, 20132013-02-16
On Thu, 14 Feb 2013 19:04:52 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:> >>>> >>>> Well, some for sure. Ten a year? 200? >>>> >>>> Time to start scribbling. >>> >>> We might make two or more models. Some dependency on price, =features, and>>> performance for sales outside this ng. Within the ng we could =probably>>> make and deploy one to two dozen. Then with real world experience i >>> think we could do a better job of selling it outside. >>> >>> ?-) >> >> How practical do you think it would it be to add temperature >> characterization? I'd be interested in that. > > >Just a SMOP. Measure Delta V_BE at three known currents, dancing back=20 >and forth as needed to take out the effects of drift and R_E. Should be==20>able to get Theta_JA and maybe the thermal mass of the die + paddle. > >I'd like to be able to measure noise as well. > >It will be interesting to figure out how to make a test fixture that=20 >prevents all transistors from oscillating under all conditions. Maybe=20 >the thing to do is to sell the tracer cheap and make money off the=20 >disposable test boards. (Shades of early IBM.)Good fixtures and such are frequently more expensive that the basic test equipment. ?-)
Reply by ●February 16, 20132013-02-16
Am 16.02.2013 05:47, schrieb josephkk:> Good fixtures and such are frequently more expensive that the basic test > equipment.A universal fixture is probably too hard. It might be better to build a tracer box that has USB, power supply, ucontroller, A/D and D/A that produces and expects only normalized voltages, say +/-2.5V and a DUT board that scales this to the values really required, electrically and mechanically. Requirements for an avalanche diode and a BFG640 are quite different. BTW in one of the few rational corners of diyaudio.com is a thread on a Chinese curve tracer: < http://www.diyaudio.com/forums/solid-state/151253-diy-curve-tracer-pc.html > regards, Gerhard
Reply by ●February 16, 20132013-02-16
On Fri, 15 Feb 2013 20:36:40 -0800, josephkk <joseph_barrett@sbcglobal.net> wrote:>On Wed, 13 Feb 2013 22:10:49 -0800, Jon Kirwan <jonk@infinitefactors.org> >wrote: > >> >>> >>>Ebbers-Moll is ok for bipolar but i would like to get Gummel-Poon models. >> >>I agree. I was just pointing out that it starts out >>interesting at the DC level and gets even more interesting >>later. This is an area I really enjoy. >> >>Take VA. The easiest way is to extrapolate Ic vs Vce in the >>CE configuration. But the error can be very high. Another way >>is to measure the slope very near Vbc=0. Another way, though, >>is using ln(Ic) vs Vbe at two different Vbc values, computing >>it as a ratio. And it's better done that way. But that >>assumes basewidth modulation is negligible. So additional >>tests using different Vbe to see how well the assumption >>holds may be useful. >> >>I'll be picking up a few BJT testers; 575, 577, and fairchild >>6200, in a couple of months. >> >>>MOS models are a different subject that i didn't get to study. >> >>I'm in a similar boat. I've only basic knowledge here. They >>don't seem as intriguing, though. >> >>Jon > >While i may be ignorant of the MOS models there are many more of them, at >least 9 IIRC. JT would know this well. As i understand it MOS 1 thru 3 >are roughly of the grade of E-M 1 and 3 thru 6 span E-M 2 to G-P and 7 >above account for even more device physics. > >?-)Every simulator has their own numbering system :-( The only somewhat standard ones are Level=1,2,3... the schoolboy textbook levels... you can write equations that sort of make sense... but they don't fit very well, particularly sub-threshold. Models of choice are BSIM3+ and EPFL-EKV, however they may happen to be numbered. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | 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.
