Experimental Characterization of a Load Modulated Balanced Amplifier with Simplified Input Power Splitter

This paper presents the experimental characterization of a load modulated balanced amplifier for base station applications using a single input configuration. An off-the-shelf power splitter is used with coaxial cables of different length to divide the input power between the branches. The effect of the phase offset is assessed experimentally by CW single tone and modulated signal measurements, and the results are discussed. With a proper selection of cable length, the amplifier achieves a CW output power of 48 dBm and a 6 dB back-off efficiency of 44 % at 1.9 GHz, while it maintains an output power higher than 47.5 dBm and a back-off efficiency higher than 32% between 1.8 and 2.3 GHz. The amplifier, tested with a Long Term Evolution signal, can be linearized with a digital predistorter to comply with spectral regrowth requirements.