A lot is said about the power needs of IoT devices, but the impact of those needs on test and measurement is also significant

If
someone was to develop a “forever battery,” chances are good that power
efficiency would fall much lower on the priority scale for electronics
engineers than it does today. But despite countless research
investments, no such battery is in the offing. Instead, in the real world,
designers must do everything possible to limit power consumption. This is
especially true for the IoT, says Tektronix Applications
Engineer Seshank Malap, who sees the IoT spurring a wave of power-related
innovation both in design and test and measurement.

Malap
has worked in the power industry for the past six years designing and testing
power semiconductors, UPS systems, automotive battery chargers, and automotive
motor drives. We talked to him about the changes that he sees occurring in the
industry from both design and test-and-measurement perspectives.

Q: How is the rise of the IoT impacting
the power industry?
A:
The need for more efficient power utilization has been growing exponentially
over the past decade due to the need for being connected all the time. With the
rise in the IoT, an increasing number of physical objects
are being wirelessly linked together. This is leading to huge numbers of IoT
sensors and devices that need to stay on and transmit day in and day out so
they can collect and stream vast amounts of data. This requires a lot of power.

The
continuous always-on aspect of IoT devices and the fact that most of them are
battery-operated demand new solutions to power management. Power engineers
are being asked to push the limits to achieve super high-power efficiencies
and ultra-low consumption in order to squeeze out as much power as they can
from a source. Power efficiencies in high 90s and power consumption and sleep
mode currents in nano- to pico-amps are becoming quite common.

Meeting
these requirements is driving innovation across the entire power ecosystem,
including the emergence of new test-and-measurement technologies.

Q: What challenges are facing engineers
in the IoT era?
A:
There is no question that the engineering and testing challenges brought on by
the IoT are immense. Engineers must figure out how to squeeze more power out of
these new devices and, more importantly, how to actually test and validate that
designs will work in the real world. Similarly, the need for super-high
efficiencies and small form factors in power designs has pushed engineers to
use higher and higher switching frequencies and smaller component packages.
This has led to the development and use of new wide-bandgap switching
technologies such as gallium nitride (GaN) and silicon carbide (SiC), which can
switch significantly faster than traditional silicon devices and provide a
compact package. This comes with its own set of very difficult testing
challenges.

All
in all, however, these trends are exciting for the future of power designs and
are one of the key innovation areas in the electronics industry. I think that we
will see some awesome progress out of these changes. But it will require a lot
of work from engineers to solve the aforementioned challenges. Hopefully, those
of us in the test-and-measurement space can help them along the way by at least making their testing jobs easier and (ahem) more efficient.

Tektronix-IsoVu-Probe

Demand for power efficiency in IoT
designs has spurred innovation in power conversion design, which has, in turn,
spurred improvements in test equipment design, such as this Tektronix IsoVu
probe with a million-to-one common mode rejection capability. Image source:
Tektronix.

Q: What are some other trends and
challenges in this space?
A:
Apart from the challenges involved with super-high efficiencies, smaller form
factors, and ultra-low power consumption, there’s a flood of ever-changing
regulatory standards that are pulling power design in the direction of even
more efficiency. For example, the U.S. Department of Energy recently came out
with its Level VI efficiency standard for external power supplies (EPSes) for
consumer products, adding more efficiency requirements than ever before. Not to
be outdone, the European Union has released the Code of Conduct (CoC) Tier 2,
which is even more stringent than the DoE’s Level VI.

The
standard bodies are going for higher efficiencies, which means more testing for
the same kinds of devices, especially for power supplies. These requirements
are true for pretty much every vertical industry, so the impact is pervasive.
And the impact isn’t limited to power supplies or battery chargers; a recent
standard just came out for LED drivers pushing for electric as well as electric-to-optic conversion efficiency.

The
standards are, in many ways, a designer’s worst nightmare. Because the standards
(and others like them around the world) are living documents, engineers must be
constantly ready to push for higher efficiencies. Every four years or so, the
standards go to that next level of power efficiency and lower standby power
consumption requirements. In addition to being efficient when it’s running, a
device must demonstrate really, really low power consumption when it’s not
doing anything.

Q: What role does test and measurement
play in enabling innovation in this segment?
A:
To understand the role of test and measurement, it’s important to understand
key trends and challenges. As mentioned earlier, getting higher efficiencies
requires a lot of innovative design methods, one of which is going to higher
switching frequencies. This explains why wide-bandgap power devices are
becoming quite popular in new power electronic designs. But these devices come with
their own testing challenges. On one hand, you need extremely high bandwidths,
and on the other hand, you need very high sensitivity as the switching and gating
signals become more critical and sensitive. High frequency of operation also
raises the need to measure more signals at the same time to optimize timing and
duty cycle to get the best out of the design.

The
need for testing and evaluating at the component level also increases
significantly when deploying new technology such as GaNs and SiCs. The devices
need to be tested for breakdown up to thousands of volts and, at the same time, vetted for leakage currents that can be as low as femto-amps. Robust testing of
these devices, all the way from the wafer to the package parts, becomes quite
critical given the demanding designs that they are deployed in.

At
the system level, the needs for testing for extreme high efficiencies, smaller
incremental design changes to meet the efficiency requirements, and testing
accurate power consumption in all operating modes are becoming quite crucial.

It’s
safe to say that testing accurately at far more test points in the system and
at all stages of design is becoming more important than it used to be. The
testing tools and techniques of old are simply not sufficient for the changing trends
facing power designers.

Q: Can you talk a little more about the
new materials?
We
hear a lot about wide-bandgap devices. They’re basically GaNs and SiCs. SiC is
driven by higher power needs and thermal stability, and GaN is driven by faster
rise times and fall times. These trends introduce new complexities into power
conversion circuits with faster switching speeds (need to measure the floating
Vgs and Vds measurements in any H-bridge topologies) and more sensitivity for
gate threshold voltage and timing. Also, because of the high frequency of
operation, more signals need to be looked at simultaneously. All of this
requires new test tools and new methodologies to optimize performance for a
given application and to ensure reliability.

Q: How is the test-and-measurement
industry helping designers address these new requirements?
A:
The industry, overall, has done a good job of supporting the power industry, and
designers can find instruments and software solutions for power electronics
design that cover everything from component testing to final compliance testing
of a finished product. Specific technologies range from source measure units
(SMUs) and parametric testers at the component levels to oscilloscopes and
power analyzers, as well as tools such as low-cost spectrum analyzers for
conducting EMC pre-compliance testing. Day-to-day instruments such as sampling
digital multi-meters are now available that can resolve down to pA sleep
currents and still show pulsing currents up to 1 MHz, making it possible for
engineers to characterize DC power profile in all operating states for complex
IoT sensors and, in turn, maximize battery life.