New-Tech Europe Magazine | Jan 2018

Fig. 1: Measuring the gate source (C1, C2) and output voltage (C3) of a resonant converter; source: Rohde & Schwarz

Fig. 2: Measuring the switching cycle of a GaN-based power factor correction (PFC) output stage; source: Rohde & Schwarz

points where the signal conductor and the ground are connected are very important. The unbalanced design used in isolated input stages results in much lower capacitance between the signal path and earth potential compared to what exists between the ground path and earth potential. In order to obtain satisfactory measurement results, the signal path should be connected to the appropriate measurement point.

small conductor loops are soldered onto the contact points so the passive probes can be connected there. In certain situations, a BNC connector can also be installed as an alternative. BNC adapters can then be used with the probe in order to achieve a nearly ideal connection. Differential probes can generally be connected arbitrarily in the circuit. However, when making measurements with isolated input channels, the exact

measurements on advanced SiC and GaN semiconductors. Moreover, it can be battery-powered for mobile applications. Unlike other oscilloscopes with isolated inputs, the R&S Scope Rider provides analysis capabilities on the level of laboratory oscilloscopes, including an extremely fast acquisition system with an acquisition rate of up to 50,000 signal waveforms per second, flexible trigger functions and a wide range of automatic measurement functions. Correct connections are essential Performing high-quality measurements on power electronics requires the right test instrument and the right probe as well as careful attention to the correct connection. Passive probes are ideal for measurements with an oscilloscope that has isolated input channels. Here, the contacts with the signal and ground connections must be as short as possible in order to minimize ringing and achieve the highest possible common-mode rejection. Ground springs generally help to ensure optimal contacting when using a passive probe. However, when measuring hazardous live voltages, prefabricated contact points must exist for safety reasons. Normally,

Fig. 3: Prefabricated conductor loops for safe measurement of hazardous live voltages using passive probes and an oscilloscope with isolated inputs; source: Rohde & Schwarz

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