Design and Simulation of an Asymmetric Orthogonal LMBA for Improved 10 dB OBO Efficiency Over an Octave Bandwidth

This paper presents a new topology for the Orthogonal Load Modulated Balanced Amplifier using a previously explored Doherty-like mode of operation, with one device acting as a main in class AB and the other in class C as an auxiliary, to enhance efficiency at 10 dB of output back off. By employing an asymmetric structure with a smaller main device, the back-off efficiency can be tuned to peak at 10 dB. Simulation results show that back-off efficiencies of 41–57 % can be achieved over an octave bandwidth of 1.2-2.4 GHz with saturation output powers 44–46 dBm. Furthermore, the paper explored the impact of using two different reactive terminations, one being a low-loss switch with four terminations and the other a lossier switch with eight terminations. The simulation results show that this device is promising as a high-efficiency, high-power device well suited for high PAPR signals.