SiC Varactors for Dynamic Load Modulation of High Power Amplifiers

SiC Schottky diode varactors with a high breakdown voltage, a high tuning ratio, and a low series resistance have been designed and fabricated. These characteristics are particularly necessary for the dynamic load modulation of high power amplifiers (PAs), which is an attractive alternative to other efficiency enhancement techniques. For a SiC Schottky diode varactor with a 50-$\mu\hbox{m}$ radius fabricated by using a graded doping profile, a breakdown voltage of 40 V, a tuning range of 5.6, and a series resistance of 0.9 $\Omega$ were achieved. The results show the great potential of this type of varactors for the use in the dynamic load modulation of high power amplifiers.