Evaulation_Engineering_March_2020 - 20

POWER SEMICONDUCTOR TEST

for repeatable and reliable measurements.
Additionally, high-frequency current measurement is extremely difficult with no
perfect solution."
At APEC, Keysight will demonstrate
products including B1505/6A static device analyzer/curve tracer, the PD1500A
dynamic device analyzer/double-pulse
tester, and the PD1000A power-device
measurement system for advanced modeling. Keysight will also present a paper
regarding the challenges presented by
testing high-frequency power semiconductor technologies (IGBTs, SiC, GaN).

SMUs and analyzers
Keithley, a Tektronix company, has introduced several products for power semiconductor test. For high-power semiconductor characterization, the company
debuted the Keithley 2470 High Voltage
SourceMeter, which offers a 1.1-kV output,
10-fA resolution, and 0.012% basic measurement accuracy.
"As SiC and GaN devices drive the need
for more efficiency, characterizing their
R DS(ON/OFF) behavior becomes more critical," said Wilson Lee, technical marketing
manager, Americas. "The 2470 fills a vital
position for engineers either in a production setting or for benchtop work."
Lee said the company also recently
launched two SMU modules for its
4200A-SCS parameter analyzer. "These
SMUs address the needs of modern production environments, where high capacitances of test setups become unavoidable
but low current measurements are still required," he said. "Low currents get harder
to measure as you increase capacitance
due to increased time constants requiring longer settling times. The 4201-SMU
and 4211-SMU modules offer greater max
capacitance specifications to meet the
needs of future testing."
The company has also launched a widebandgap reference test system. "This reference design represents an optimal system
for making critical in-circuit, real-time
measurements on GaN and SiC power
semiconductors," Lee said. "It addresses
the needs for high-bandwidth, highvoltage, high-common-mode-rejection
measurements that prove extremely difficult with these fast rise-time devices in

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half-bridge and full-bridge topologies. The
system is available as a kit; however, most
users customize it to fit their specific applications. The system includes a 5 Series
oscilloscope with a power measurement
and analysis package installed and IsoVu
optically-isolated differential probes to
enable fast rise-time measurements while
eliminating common mode noise."
Lee added that the Tektronix 4/5/6
Series 12-bit oscilloscopes offer the higher
vertical resolution that allows engineers
to make accurate measurements over the
higher dynamic ranges becoming commonplace as switching voltages increase
with GaN and especially with SiC. He said
the company has also "...added the ability to synchronously observe time- and
frequency-domain activity, which is valuable for EMI troubleshooting made more
challenging by fast, high-voltage switching. We call this 'Spectrum View.'"
The company also offers an arbitrary/
function generator with double pulse
testing. "To measure turn-on and turnoff characteristics, the new AFG31000
now comes with the ability to generate
double-pulse test signals from the front
panel," Lee said. "Test signals are specified
by voltage level and the on-time and offtime for the two pulses. This makes the
AFG31000 the first such AFG with this
functionality built-in."
At APEC, the company will present a
variety of focused application demos-including power semiconductor characterization, wide bandgap power conversion,
a 3-phase motor drive, EMI debug, double
pulse test, and power integrity.
Newark offers the Keithley 2470
High Voltage SourceMeter, and James
McGregor, global head of Test and Tools,
elaborated on its capabilities; "It offers
4-quadrant precision voltage and current source/load coupled with measurement on a touchscreen user interface. The
2470 SMU adds capabilities in measurements such as breakdown voltage, leakage current, isolation testing, hipot, and
dielectric withstanding tests. With the
2470's 1,100 V and 10 fA capability, it is
optimized for characterizing and testing
high-voltage, low-leakage devices such
as SiC and GaN wide-bandgap power
semiconductors."

McGregor called the 2470 SMU just one
example of a product in the distributor's
Test and Tool range, which has expanded
by over 4,000 products globally in the
last year. "Newark remains committed
to equipping its customers with the very
best products from leading suppliers and
has invested over $5 million in Test and
Tools alone in 2019," he said.
Newark also offers options for powersemiconductor test. "The Keithley Model
8010 high-power device test fixture provides safe and easy connections for testing packaged high-power devices up to
3,000 V and 100 A. It also provides connections for Keithley's source/meter units.
... Newark's portfolio of test equipment is
all inclusive; engineers can find solutions
to all their test needs in one place."
McGregor added that the very low
leakage currents measured in power
semiconductors impose challenges related to sufficient noise immunity at the
low currents. "It may be necessary to use
special triaxial cables, of which Newark
offers several options, to overcome this,"
he said. "In addition to triaxial cables,
special safety probes are needed when
measuring high voltages typical of power
semiconductors. Newark offers a variety
of low-noise triaxial cables and highvoltage safety probes from manufacturers
such as Keithley, Keysight, and Pomona,
supporting engineers as they overcome
these challenges and enabling them to
test safely and confidently."

Scopes and options
Rohde & Schwarz offers several products
for power semiconductor test, including
R&S RT-ZHD high-voltage differential
probes; R&S RT-ZPR20 and R&S RTZPR40 power-integrity probe; and the
R&S RTx-K31 power-analysis option and
R&S RTx-K36 Bode-analysis option for the
company's oscilloscopes.
In addition, "The R&S RT-ZD10 active
differential probe, together with the R&S
RT-ZA15 external attenuator, permits
the measurement of voltages up to ±60
VDC/±42.4 VAC (peak) at a bandwidth
of 1 GHz," said Marcus Herdin, marketsegment manager for industry, components, research, and universities at Rohde
& Schwarz.

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