AWG + Oscilloscope as Curve Tracer  - Page 1
Forum section: electronics / testgear

author: JimKnopf
author_rank: Frequent Contributor
timestamp: March 22, 2025, 05:12:30 pm
content: I stumbled across this topic some days agohttps://www.eevblog.com/forum/testgear/rigol-dp832-power-supply-as-automated-curve-tracer/. @RoGeorge made a script for his programmable Rigol DP832 PSU which is very interesting.Since i'm the proud owner of a EEZ BB3 PSU which is also programmable and has already a Curve-Tracer.py installed, i successfully tested it on some Transistors and Mosfets.I found this blog post from 2014 about using a AWG and an Oscilloscope as a curve tracer for transistorshttps://www.circuitspecialists.com/blog/using-an-arbitrary-waveform-generator-and-a-digital-storage-oscilloscope-to-create-a-transistor-curve-tracer/.This week, i received a Siglent SDG6022X AWG. I was curious testing new features with this device and the blog post from 2014 looks like an interesting task.In that blog post, an additional AC source is used. I tought i could use the second channel from the SDG6022X to create that so called Full-Wave Rectified AC waveform. There is a long list of arbitrary waveforms included in the SDG6022X. The math section of the Arb waveform has a similar waveform, the function is x^2. I need the opposite direction of the waveform.I created a waveform with the function -x^2+x in the EasyWaveX app and uploaded it to the SDG6022X. Very nice tool. I setup channel 2 with this waveform, 5 Vpp. Channel 1 has a stairstep signal, 10V, 100Hz, similar to the one in the blog post.The SDS2104X HD was set to XY mode and 5 second signal persistence on screen. The figure displayed in XY mode looks very different to the one from the EEZ-BB3.Does anyone successfully tried such a setup (AWG + Oscilloscope) as curve tracer? Any hint how i can tweak the setup to match to the correct curve trace figure?

author: egonotto
author_rank: Super Contributor
timestamp: March 22, 2025, 05:30:36 pm
content: Hello,the Analog Discovery already has the curve tracer function built in. AWG and oscilloscope as curve tracer therefore work well.Can you show the time function of curve-tracer-test1.png so that we can see what is going on.Best regardsegonotto

author: JimKnopf
author_rank: Frequent Contributor
timestamp: March 22, 2025, 07:16:41 pm
content: @egonotto By time function you mean the XY settings?I attached an image of my test-board setup.

author: tautech
author_rank: Super Contributor
timestamp: March 22, 2025, 07:49:36 pm
content: Quote from: JimKnopf on March 22, 2025, 05:12:30 pmYup, our member mawyatt did some great work and shared it with us....dunno how you missed it ?https://www.eevblog.com/forum/testgear/fooln-around-with-dso-awg/https://www.eevblog.com/forum/projects/dso-awg-based-curve-tracer/

author: egonotto
author_rank: Super Contributor
timestamp: March 22, 2025, 08:12:03 pm
content: Hello,no, I mean when the x-axis is time.And you can see the progression of the two signals over time.Best regardsegonotto

author: JimKnopf
author_rank: Frequent Contributor
timestamp: March 23, 2025, 06:36:37 pm
content: @tautech Thank you for the hint. Thanks to mawyatt's nice post, i was able to get it to work with Transistors.I made several mistakes. In the first place, my selfmade waveform didn't work. Second, my stairstep wave had no offset.After using the trapezoidal waveform, mentioned by mawyatt, it started to work. I had to tweak size and position a bit. DUT was a BD139 and a BC549.I had no luck with the STP3NB90FP N-Channel Mosfet. I will tweak the settings next week. But in general it works. The signal is a bit bold. I guess thats the downside of a DSO.@egonotto I guess picture SDG-SDS_SDS-selfmade-waveform_-x_sqet2+x_.png shows what you were asking for.

author: tautech
author_rank: Super Contributor
timestamp: March 23, 2025, 07:03:19 pm
content: Quote from: JimKnopf on March 23, 2025, 06:36:37 pmGood work Jim, this is something I'm wanting to find time to experiment with also.ARB settings are the more crucial AFAIKT, ie, for MOSFET's you need to exceed gate thresholds.You might also have a look at this thread for settings to get the best from a DSO in XY mode:https://www.eevblog.com/forum/testgear/oscilloscope-music-on-dsos-post-your-results/

author: egonotto
author_rank: Super Contributor
timestamp: March 24, 2025, 12:28:58 am
content: Hello,yes, the picture shows the problem.The step function determines the base current or gate voltage parameter and should only change slowly. The collector-emitter or drain-source voltage should be displayed in the x-axis. The measured current through the collector or the drain should be displayed in the y-axis.The STP3NB90FP N-Channel Mosfet is similar in type to the IRF510,These beasts need a positive drain voltage and a positive gate voltage, if I understand correctly. However, these are power types and therefore you have to limit yourself to certain ranges, because you only have low voltages and currents with one AWG.As an example, I measured a set of curves of the IRF510 with the Analog Discovery. I had to limit myself quite a bit with the gate voltage. This is also necessary with the STP3NB90FP.Best regardsegonotto