Pico Technical Support and Discussion Forum

Guest · Posted: Wed Apr 11, 2007 2:02 pm Post subject: Need for Gain Phase Measurement

If this generic scope product could be adapted to plot the Gain and Phase versus frequency in Switched Mode Power Supply feedback loops in order to ensure unconditional Stability I would be overjoyed. The only product in the world that can do this is the AP300 from ridleyengineering and that costs $14K or £8K so I don't have one. Consider the AP300 as a product to be beaten. Most other devices are unable to do this simple measurement due to the very high background noise and I feel that a correlator algorithm is all that needs to be developed to allow your scopes to do this, you already have the signal generator.

ziko · Posted: Thu Apr 12, 2007 10:12 am Post subject:

HI and thank you for your post, having spoken to one of our engineers this is what he had to say

"Thanks for your suggestion. Frequency response analysis (or indeed impedance analysis) would certainly be an interesting application for one of our oscilloscopes with a built-in sweepable signal generator, such as the PicoScope 3206 or the new PicoScope 5204.

Taking a look at the Ridley Engineering website, their product does have hardware features which make it particularly suited to this application, and which the PicoScope (being a more general-purpose instrument) lacks.
For example, the low output impedance and high power drive capability of the AP300 would mean that you might need to use an external RF amplifier with a PicoScope in order to achieve the same power output.

Your suggestion of plotting the relative gain and phase of two oscilloscope channels across a frequency sweep of the signal generator is something we'll bear in mind when looking at future software features. However, we do also supply DLLs and programming examples with most of our products (check the product information for the particular scope you are interested in) so you could consider writing your own application to analyse the oscilloscope data and display the frequency response."

Hope this helps.

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