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R&S®Essentials | DC Power supplies fundamentals

Arbitrary and ramp function

Author: Anja Fenske, Product Manager R&S Essentials Power supplies

An arbitrary file stores voltage, current and dwell time for a certain number of points. In addition, the number of repetitions for a defined sequence of points can be specified. This allows, for example, to emulate real-world scenarios using arbitrary functions as voltage or current inputs for testing the resilience of a DUT against variations in supply voltage and current delivery.

Unlike the arbitrary function, the curve of the ramp function has a fixed shape. The ramp functionality provides a linear “fade-in” curve for the unloaded voltage versus time after switching on the corresponding output channel of the power supply. It can be used to protect circuits from damage by inrush current. The only configurable parameter for the ramp function is the ramp time from switch-on until the full unloaded voltage is reached.

Arbitrary and ramp functions with Rohde & Schwarz

DC power supplies from Rohde & Schwarz provide arbitrary functions like EasyArb or QuickArb. The parameters for the individual channels are organized according to a defined scheme, providing a certain degree of compatibility between arbitrary files.

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Properties of QuickArb function

In addition to larger parameter ranges and a higher number of points, the QuickArb function supports subgroups, specification of the end behavior, and linear ramp-shaped interpolation between points. Another advantage is the higher time resolution of 1 ms for both the minimum dwell time and the increments for advancing to the next point.

With the QuickArb functionality, not only the start of the arbitrary function can be triggered, but also the advancement of a sequence to the next point. This feature is useful, for example, for synchronizing DC voltage sweeps with procedures that take place on measurement equipment.

Arbitrary editor

Rohde & Schwarz DC power supplies offer an editor for modifying arbitrary curve shapes on the touchscreen. The unloaded voltage, current limit and dwell time can be edited for every point in the curve. Additional parameters like the number of repetitions can also be modified.

With the QuickArb editor, arbitrary curves can be stored to and loaded from ASCII files with character-separated values (CSV). With the EasyArb function, arbitrary curves are stored together with the global instrument settings. Arbitrary curves can also be loaded into the DC power supply via remote control, for example using the R&S®HMExplorer software.