Using an ADALM1000 to Measure Bipolar Transistor Gain versus Collector Current

RE: Using an ADALM1000 to Measure Bipolar Transistor Gain versus Collector Current

genebren — Fri, 28 Jul 2023 21:40:12 GMT

Nice update. Good detective work on finding/fixing the oscillations. Looking better!

RE: Using an ADALM1000 to Measure Bipolar Transistor Gain versus Collector Current

shabaz — Sat, 22 Jul 2023 20:25:30 GMT

Just saw this nice circuit, that could be adapted for (say) 0-1mA current source, based on a control voltage:

However, something like 2 x LMC6062 (or 1 x LMC6484, but there's no stock of any of the more accurate versions at Farnell) could be a better option in that circuit, since it has higher operating voltage for a more general-purpose design.

RE: Using an ADALM1000 to Measure Bipolar Transistor Gain versus Collector Current

DAB — Sat, 22 Jul 2023 17:52:28 GMT

Nice test.

I am reasonably impressed by the ADALM1000.

RE: Using an ADALM1000 to Measure Bipolar Transistor Gain versus Collector Current

shabaz — Sat, 22 Jul 2023 17:50:32 GMT

Hi Jon,

Very interesting blog. Neat trick to adjust the output based on collector current rather than directly from the base current!

I couldn't figure out the slight anomaly on the BC549C either, I guess it could be a couple of things (e.g. may the ADALM100 itself) interacting in an unexpected way! The first op-amp circuit also had that anomaly, but it was more in the second circuit, and slightly changed position, so that's probably a clue, but I couldn't solve it. Still, the chart was very interesting. I'd always wondered how much the gain changed in that range, since a lot of datasheets only have charts that often only have a subset of this, and sometimes one may want to build for a slightly different collector current.

For the few times I've tried to measure a semiconductor, I've been doing it manually so far, with a multimeter and a process calibrator (which is like a lower-res SMU, and much like the ADALM1000). I've got an old Yokogawa model, but the one in the screenshot below looks interesting, it's apparently quite accurate too, however it's not impulse-purchase price! so I probably won't buy it until I really need to. A couple of process calibrators would be neat for experimenting with semiconductors.

RE: Using an ADALM1000 to Measure Bipolar Transistor Gain versus Collector Current

BigG — Sat, 22 Jul 2023 10:56:00 GMT

This is great. As any sportsman knows, the price and brand of the sports equipment you're using does not always help that much, it is how you are able to use it that counts. And here it's similar. I really liked the way you were able to show incremental improvement and also then provided explanation along the way using the output charts from the ADALM1000. I learnt from this.

RE: Using an ADALM1000 to Measure Bipolar Transistor Gain versus Collector Current

javagoza — Sat, 22 Jul 2023 09:19:35 GMT

Thanks! I am enjoying your blog series. Keep up the great work.

RE: Using an ADALM1000 to Measure Bipolar Transistor Gain versus Collector Current

genebren — Fri, 21 Jul 2023 22:05:49 GMT

Very informative and interesting! This ADALM1000 looks like a pretty cool tool. Thanks for sharing.