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6 HEMT applications

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The HEMT was originally developed for high speed applications. The technological advantages of GaN/AlGaN HEMT result from the combination of the wide-band gap of GaN and the availability of the AlGaN/GaN heterostructure where high voltage, high current and low on-resistance can be simultaneously achieved, resulting in high power-high efficiency operation. Furthermore, the wide-bandgap offers a rugged and reliable technology capable of high voltage-high temperature operation. This opens up several industrial, automotive and aircraft applications like power and high voltage rectifiers and converters. Some of the commercial and military markets that can be targeted by GaN are shown on Fig. 6.1.⁽¹⁾

It was only when the first devices were fabricated that it was discovered they exhibited a very low noise figure. This is related to the nature of the two dimensional electron gas and the fact that there are less electron collisions. As a result of their noise performance they are widely used in low noise small signal amplifiers, power amplifiers, oscillators and mixers operating at frequencies up to 60 GHz and more and it is anticipated that ultimately devices will be widely available for frequencies up to about 100 GHz.

Fig. 6.1 Power electronics applications for GaN HEMTs (source: Yole)

In fact HEMT devices are used in a wide range of RF design applications including cellular telecommunications, Direct broadcast receivers - DBS, radar, radio astronomy, and any RF design application that requires a combination of low noise and very high frequency performance HEMTs are manufactured by many semiconductor device manufacturers around the globe. They may be in the form of discrete transistors, but nowadays they are more usually incorporated into integrated circuits. These Monolithic Microwave Integrated Circuit chips, or MMICs are widely used for RF design applications, and HEMT based MMICs are widely used to provide the required level of performance in many areas.⁽²⁾

Fig. 6.1 RF applications for GaN HEMTs  (click to run)

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