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Wide-Bandgap Semiconductors Find Homes in Space

necessary to select components in which the effects produced by radia-
tion have been measured and declared.
WBG ADVANTAGES IN SPACE-BORNE SYSTEMS
Reduced weight and size, together with high efficiency and reliability,
are fundamental requirements for components intended for use on
spacecraft. GaN power devices provide the highest level of efficiency
in the smallest footprint available today. Gallium nitride also has
excellent characteristics in terms of electromagnetic compatibility
(EMC): The reduced parasitic capacitance decreases the energy stored
and released during the switching cycles, while the reduced footprint
improves the loop inductance, particularly insidious as it acts as a
transceiver antenna.
Power devices used in critical applications such as space mis- Figure 3: Freebird’s GaN adapter module
sions, high-altitude flights, or strategic military applications must be (Image: Freebird Semiconductor)
resistant to failures and malfunctions caused by ionizing radiation.
Commercial GaN power devices offer significantly higher performance
than traditional rad-hard devices based on silicon technology. This tested for TID radiation. The ISL7023SEH 100-V, 60-A GaN FET and
allows the implementation of innovative architectures for applications ISL70024SEH 200-V, 7.5-A GaN FET provide up to 10-orders-of-
in satellites, data transmission, drones, robotics, and spacecraft. magnitude-better performance than silicon MOSFETs while reducing
package size by 50%.
ENHANCED GaN HEMT They also reduce power supply weight and achieve higher power
Rad-hard MOSFETs have reached their technology limits with large die efficiency with less switching power loss. At 5-mΩ R DS(ON) and
sizes and a performance figure of merit (FoM), expressed by the formula 14 nC (QG), the ISL70023SEH enables the industry’s best figure of
FoM = R DS(ON) × C iss , which is much higher than that of an eGaN transis- merit. Figure 1 shows the very low R DS(ON) .
tor. The FoM is a very important parameter: The smaller the value, the VPT Inc. offers the SGRB series of DC/DC converters, specifically
better the efficiency of the system. designed for harsh radiation environments in space applications. Based
In addition, eGaN HEMTs are easier to drive, as they require 10× to on advanced GaN technology, the SGRB series provides high efficiency,
40× less gate charge than the best rad-hard MOSFETs. GaN devices can resulting in reduced system size, weight, and cost.
also be mounted directly on the ceramic substrate without requiring With up to 95% efficiency, the series’ GaN technology results in
any external package. It is possible to eliminate wire bonds and related greater efficiency compared with traditional radiation-hardened silicon
inductance, enabling very high switching rates. The eGaN switching products. It has been designed specifically for space-borne telecommu-
speeds are determined only by the resistance and capacitance of the nications in which high efficiency, low noise, and radiation tolerance
gate and drain nodes. are imperative (Figure 2).
Switching times can easily reach sub-nanosecond levels, so particu- Freebird Semiconductor offers a wide selection of high-reliability
lar attention should be paid to both the design and PCB layout phases GaN HEMT discrete devices integrated into GaN adapter modules
of development when using these high-performance devices. (GAMs), creating the patented circuitry found in its multifunction
power module series. These universal GaN adapter modules (Figure 3)
RAD-HARD GaN SOLUTIONS incorporate eGaN switching power HEMTs with GaN-based high-speed
Renesas Electronics, a leading supplier of advanced semiconductor gate drive circuits for use in commercial satellites.
solutions, has developed the industry’s first rad-hard 100-V and 200-V The rad-hard FBS-GAM01-P-C50 single low-side power development
GaN FET power solutions, suitable for enabling primary and secondary driver module incorporates GaN switching power HEMTs in a nine-pin
DC/DC converter power supplies in space-borne systems. These GaN SMT overmolded epoxy package. Integrated devices include Freebird’s
FETs have been characterized for destructive single-event effects and FDA10N30X output power eGaN HEMT switch and an output clamp
Schottky diode, optimally driven by high-speed gate drive circuitry
consisting entirely of eGaN switching elements. It also includes 5-V
input V BIAS overvoltage clamping protection with V BIAS undervoltage
driver disable and reporting. The SMT overmolded epoxy package pro-
vides an engineering development platform for the FBS-GAM01-P-R50
flight unit version.
CONCLUSION
A reliable, continuous power supply is essential to the success of a
space mission. In real-world applications, the main advantage of
switching to SiC- or GaN-based broadband semiconductors is the
increased power conversion efficiency.
The ability of SiC- or GaN-based broadband semiconductors to oper-
ate at high temperatures also has significant advantages. Not only can
these devices be used in higher heat environments, they require less
overall cooling, reducing the space and cost of cooling components in
the power converter. ■

Maurizio Di Paolo Emilio is a staff correspondent at AspenCore,
Figure 2: VPT’s SGRB series of DC/DC converters (Image: VPT Inc.) editor of Power Electronics News, and editor-in-chief of EEWeb.

www.eetimes.eu | APRIL 2020