Evaulation_Engineering_March_2020 - 18

POWER SEMICONDUCTOR TEST

Peter Hancock, president of Focused
Test, identified some key applications the
company addresses: GaN HEMT test for
power conversion to 1,000 V, GaN IC test
for power conversion, GaN IC test for lidar
applications in autonomous vehicles, and
SiC test for power conversion and motor
drivers > 2,000 V. Key challenges, he said,
include minimizing stray capacitance
to perform dynamic R DS(ON) test of GaN
HEMTs with less than 1 ms of measurement delay as well as minimizing stray
capacitance and drain-gate crosstalk for
timing tests of GaN HEMTs with tON/tOFF
less than 1 ns at V DS greater than 800 V.
Hancock cited several trends. The need
for improved efficiency is driving power
semiconductor technology for cloud
computing centers and solar installations, whereas consumer products benefit
from efficiency improvements as well as
reduced size and cost. And electric and
autonomous vehicles require efficiency
plus reliability.
As for what customers are looking for,
Hancock said, key factors are ease of use
and open software that allows users to
modify test routines without the support
of the test vendor. Also important is a
willingness to partner. "Wide-bandgap
tests are not yet well-defined, and test
needs are changing fast. Customers
need the test vendor to partner and respond quickly to new requirements." In
addition, he noted, "OSAT's have limited
test capability in wide bandgap. Focused
Test offers a 'Flex Capacity' program for
OSAT's geared towards wide-bandgap
applications."
Focused Test will present the FTI-1000
in many configurations at APEC, March
8-12 in New Orleans.

IGBTs, Si MOSFETs, and SiC devices
Keysight Technologies has recently introduced the PD1500A dynamic powerdevice analyzer/double-pulse tester, along
with software, fixtures, and probes. "It
is a complete double-pulse test solution
for IGBTs, Si MOSFETs, and SiC devices,
according to Ryo Takeda, power semiconductor solution architect; Bernhard
Holzinger, power semiconductor technical architect; and Mike Hawes, power
solution consultant.

EVALUATION ENGINEERING MARCH 2020

Sponsored by

Focused Test Inc. FTI-1000 tester with
RDS(ON) test station and DUT board.

"Repeatable and reliable measurement
is the key challenge to designing a doublepulse test system for WBG devices," they
said. "Because of the quicker switching
speeds and faster edges, any parasitic inductance and capacitance in your power
loop along with gate-loop design of the
circuit can significantly affect your measurement results. In turn, this will provide
unrepeatable and incorrect parameter extraction from these waveforms."
They added, "Because of the higher power applications for WBG devices (for example, solar inverter, traction inverter), thermal management is critical to the design
of power converters. Keysight's PD1500A
enables DPT parameters to be determined
over a controller temperature range."
Keysight focuses on key end-use applications including electric-vehicle powerconverter test and alternative-energy
power-converter test. In addition to the
power-semiconductor dynamic characterization requirements, thoroughly testing the efficiency, performance, and reliability of these power converters is critical
to supporting the growth of these markets, said Takeda, Holzinger, and Hawes.
"Keysight supplies additional solutions for
EV power converters and grid-edge power-converter applications," they added.

"The biggest trend in power semiconductors is the introduction of new widebandgap power semiconductor technologies," they said. "They have significant
advantages over Si-based [solutions] (that
is, switching speeds, efficiency, thermal
properties, higher voltages), but they are
not as well developed and characterized.
Therefore, the reliability is not sufficient
for some applications. There will be a lot
of focus on improving the reliability of the
WBG semiconductors, so mission-critical
applications (EV, alternative energy) will
transition to these new technologies."
The key capability is repeatable and
reliable dynamic characterization (DPT)
of faster switching, higher voltage power
semiconductors, they said, adding, "A
complete DPT solution will significantly
improve customer's experience in characterizing the dynamic parameters of power
semiconductors. Effective and repeatable
DPT design is surprisingly difficult."
The design of a DPT system presents
many challenges because of the combination of high frequency and high power.
"RF effects need to be considered, which
is not typical for power-converter designers," they said. "Minimizing parasitic inductance and capacitance in the
power loop and the gate loop is critical

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