• • • POWER SUPPLIES • • •
Focusing on very low currents and voltages
Battery-powered devices are getting smaller and smaller, and their current consumption is dropping to levels that are difficult to measure, but source measure units are up to the task, says Andreas Schütz, Rohde & Schwarz’s manager for device technology and architecture
Smart watch
S
mart watches and other small devices operate on very small currents down to the nanoampere range. To enable technically
sound development of devices with very low current consumption, power supplies that can both measure and reliably supply extremely small currents and voltages are needed – such as the new R&S NGU series. It enhances the range of Rohde & Schwarz
general purpose lab DC power supplies with a class of precision source measure units (SMU). Two different models are available, both of which can function as a source and a sink. The R&S NGU201 operates in two-quadrant mode, while the R&S NGU401 can also operate in four-quadrant mode, allowing it to supply and measure both positive and negative voltages, for example to test semiconductor devices.
Wide measurement ranges,
rich features Set or measured values can be viewed with up to 6 1/2 digits on a large touch display, which also shows measured current and voltage waveforms and other graphics with high resolution. Both models can source and sink power up to 60W, and currents up to 8A. The units achieve fast load recovery times of under 30 µs in voltage priority mode and under 50 µs in current priority mode. The R&S NGU user interface and features are
based on the R&S NGL/NGM series of special power supplies. For example, the interfaces (LAN,
Extremely short-term voltage variations, which might otherwise go unnoticed, can be captured with the FastLog function.
24 ELECTRICAL ENGINEERING • DECEMBER 2021/JANUARY 2022
electricalengineeringmagazine.co.uk
USB, GPIB) and current, voltage, power and temperature protection functions are the same. The new top-end units provide even more
sophisticated functions for shaping the output voltage or current. For example, the QuickArb function allows users to define up to 2048 current or voltage points per cycle, at intervals as short as 100 µs. It is also possible to interpolate between these points to achieve an even finer resolution. For analysis, the FastLog function with acquisition rates of up to 500 ksample/s reveals extremely short-term current and voltage variations. Specifically designed for wireless
communications applications, the R&S NGU201
can optionally be turned into a battery simulator with a graphical display. It can accurately simulate user-configurable primary and secondary batteries, thanks to its integrated variable output impedance. The optional digital voltmeter that is galvanically isolated from the channel circuitry is another handy feature that in many cases eliminates the need for an additional instrument. For users that require flexibility beyond
modeling current and voltage characteristics with the QuickArb function, the four-quadrant R&S NGU401 provides a modulation input for feeding arbitrary waveforms. This enables the unit to act as an AC current or voltage source and to
Photo provided by Rohde & Schwarz
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