Bandwidth and Power Back-Off Performances of a Class-EM/F3 Power Amplifier

This paper presents the design of a broadband high-efficiency Class-EM/F3power amplifier (PA). The PA exhibits a significantly reduced peak drain voltage compared to its predecessor (Class-EM) and a large fractional bandwidth of 34.3% at peak power as well as 6 dB output back-off power (OBO) while satisfying the zero voltage switching, zero voltage derivative switching, zero current switching, and zero current derivative switching conditions to minimize power dissipation within the active device. A Class-EM/F3 PA employing a transmission-line load network was proposed and implemented using GaN HEMTs. The PA exhibits a drain efficiency (DE) of 77%, a power-added efficiency (PAE) of 72% at a peak output power (P-{text{out}}) of 42.1 dBm at 1.8 GHz. With P-{text{out}} backed-off by 6 dB, the PA delivers a DE of 41% and a PAE of 40%. Across a frequency range from 1.4 to 2 GHz, the PA delivers DE > 67%, PAE > 58%, and a P-{text{out}} of 41.2pm 1 text{dBm}. At 6-dB OBO, the PA delivers DE > 39%, a PAE > 34%, and a P-{text{out}} of 35pm 1.2 text{dBm}.