Hi Guest user!

   6 HEMT applications

    6.2 HEMTs in integrated power circuits

.

Highly modern power transistors based on gallium nitride (GaN) enable power electronic switches to operate at much higher switching frequencies compared to those based on silicon (Si). An increased power density per volume and per weight, reduced costs, less material use and, in the case of a mobile system, increased system efficiency are among the advantages.

The scientist in Fraunhofer institute have develop a resonant DC/DC converter with GaN transistors (Fig. 6.4), which is to operate with switching frequencies well above 1 MHz and a nominal power of 3 kW. The simultaneous occurrence of extremely high switching frequencies and high transmitted power requires the use of special, innovative inductive components.

Fig. 6.4 

CPES has created a design of a multichip Gallium-Nitride (GaN) power module for high-frequency power conversion (Fig. 6.5). The module is designed with the HRL 600 V Gallium-Nitride (GaN) enhancement-mode HEMT device. To exploit the capability of fast switching with low loss from high-voltage GaN devices, different layout structures have been analyzed to reduce power loop parasitic inductance and improve switching performance. The approach investigated is based on a multi-chip module where small-current-rated dies are placed in parallel to achieve higher current handling capability. Finite-element analysis (FEA) and switching circuit simulation show that the multi-layer powerloop design can effectively reduce the gate loop inductance and voltage over-shoot on the devices. This multi-layer design also improves current sharing of the multi-chip module during switching operation.⁽¹⁾

Fig. 6.5 Cascade multi-layer structure; top-left: cross section; top-right: top view; bottom-left: full picture of the module; bottom-right: final experimental converter⁽¹⁾

__________________