Can we use ADALM 2000 (M2K) for measuring loop (Bode plot) for switching power supply. I tried to measure feedback loop gain for buck converter but it done not show properly.

Hi,

Yes, the ADALM 2000 can perform Bode plot measurements using the Network Analyzer tool in Scopy. For setup instructions, refer to this guide: M2K Network Analyzer Guide.

Note: the firmware version 0.32 has a known bug causing spikes in the Network Analyzer, which may affect your results. The current solution is to downgrade to firmware version 0.31 until a fix is released.

Thanks for response.

I am using firmware version 0.31. I already referred m2k network analyzer guide as loop measurement results were not proper for buck converter .

I tried loop measurement with changing amplitude of injected signal voltage from 10mv to 1volt, on/off of DC filtering, changing setting time, changing sample rate, changing periods and average but I didn't get success. 

One thing I observed that if I increase average 2 onwards, the scopy application closes automatically after some time.

I searched on internet for loop measurement with ADLM2000 (m2k) for switch mode power supply but I didn't find any so I doubted that it may not be suitable for SMPS loop measurement.

Please suggest or guidelines if any.

Thanks.

After various tries I succeed to get bode plot using ADALM2000 (m2k). For this I had to set scope channel 1 & 2 in AC coupling then I got the bode plot for buck converter board LM2596S. Screen shot is attached herewith for reference. In DC coupling I am getting meaningless bode plot. Further it is found that after 10 kHz onwards plot is not smooth. I changed injection signal amplitude from 20 mV to 1V but 10 KHz onwards plot is not smooth. Please tell me if any setting is required.

I am using Scopy version: 1.4.1-f4beeb1 and using firmware version 0.31.

DOCX

This isn’t really my area of expertise, but there’s a great guide you can check that walks you through: Loop Bode Plot Measurement and Considerations. It covers key details like where to inject signals, bandwidth limits, and other tips to ensure accurate measurements.

PS: As for the crashes when using an averaging setting of 2 or higher, this is a known issue that’s been addressed in development and will be fixed in the next Scopy release.