Class-E power amplifier optimization for operation above maximum frequency

The optimized Class-E power amplifier (PA) for operation above the maximum frequency is described. We have found that the performance of the Class-E PA above the maximum frequency can be enhanced by the bifurcated current through saturation. The performance of the Class-E PA can be further improved by the inductive second harmonic tuning and power matched fundamental load. The resulting saturated amplifier delivers higher output power and efficiency because of the tuned load and the proper second harmonic voltage component generated by the second harmonic load matching. A highly efficient saturated amplifier is designed using Cree GaN HEMT CGH40010 device at 3.5 GHz. It provides a drain efficiency of 75.8% at a saturated power of 40.2 dBm (10.5W).