High Efficiency GaN HEMT Power Amplifier optimized for OFDM EER Transmitter

We have proposed a highly efficient power amplifier (PA) for the envelope elimination and restoration (EER) transmitter using gallium nitride (GaN) HEMT. The class AB, B, C and F mode PAs have been implemented with EUDYNA's 10 watts GaN HEMT and compared the bias modulation performances in order to investigate the optimum PA structure. The proposed class F mode PA has been biased at class C and adopted a new output matching topology that improves the overall transmitter efficiency. For the WiMAX OFDM signal, the calculated overall drain efficiencies of the optimized EER amplifier, which are based on the measuremed bias dependent efficiencies, are about 73 % at an average power of 31 dBm at 2.14 GHz. The proposed highly efficient bias modulation PA for the EER transmitter provides a superior overall efficiency than that of any conventional switching or saturation mode PAs.