Page 23 - PEN Ebook March 2021

Semiconductors DESIGN

Figure 4: Parallel half-bridge CoolGaN™ evaluation platform.

even more so when operating them in parallel. operation can also be undertaken for hard- and
However, simulations using SIMetrix transistor soft-switching at frequencies of up to 1 MHz
models show that, with small and symmetrical and power levels of several kilowatts. Continu-

gate-drive loops and the use of CM inductors, ous current of 28 A and a peak current of 70 A,
any static imbalance in current sharing is related together with appropriate heatsinking, can be
solely to differences in R DS(on) between the tran- tested. Evaluating the Transient
sistors selected.

SUMMARY Performance of Buck
COLLECTING PRACTICAL With a solid understanding of the gate drive
EXPERIENCE circuitry required, GaN power transistors can be Regulators with an
To enable engineers to evaluate GaN HEMTs in used in parallel with relative ease. The biggest

parallel operation quickly, Infineon has devel- challenge relates to the high powers and switch- Integrated Compensation
oped a parallel half-bridge evaluation board that ing frequency that many engineers will never have
features four 70 mΩ IGOT60R070D1s. Using the experienced with current silicon technologies. By Network
design guidelines discussed here, it provides a following the basic rules of good PCB layout, the
wide range of test points for in-depth analysis. use of CM inductors in the gate and Kelvin source
With an external inductor, the board can be used path and balancing currents between the transis- By Amir Ranjbar, Sr. Field Applications Engineer, Monolithic Power Systems
for both buck and boost mode tests and dou- tors, the potential for destructive oscillations are

ble-pulse testing. Pulse-width modulation (PWM) minimized. Designing the compensation network for buck compensation networks have been developed to
regulators can be tedious and may require sev- simplify the design process. Despite the bene-
For More Information eral iterations to optimize the solution. Having fits of an internal compensation network, there

an optimized control loop, which can enable are fewer knobs available to tune/improve the
fast transient response while maintaining proper transient performance on the outside. The major
▶ Infineon Technologies
stability, has become a major challenge with the challenge is how to evaluate internal compensa-
emergence of new applications such as ADAS and tion networks to ensure that they fit a specific
▶ GaN Transistor fast transient response requirements. To ad- application. This article will provide guidance on
dress these issues, buck regulators with internal how to evaluate internal compensation networks.

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