RF power amplifier design providing high power efficiency in a wide dynamic range

Recent advancements in wireless communication have aimed to increase data rates. To achieve this goal, complex modulation techniques with high peak-to-average power ratios (PAR) have been introduced. However, RF power amplifiers used in communication devices consume high power due to high PAR, leading to battery and thermal issues. Therefore, improving the efficiency of power amplifiers is crucial to design devices that are efficient in terms of size and battery usage. Traditional RF power amplifiers provide high efficiency only at saturated power levels. Efficiency significantly decreases at back-off power levels. In modulation techniques with high PAR, it is necessary to increase efficiency at back-off power levels. Various techniques have been developed for this purpose. Load Modulated Balanced Amplifier (LMBA), which is one of these techniques, has gained attention in recent years. In the LMBA technique, in addition to the power amplifier designed according to the balanced amplifier topology, a third amplifier is included in the system to modulate the output loads of the balanced amplifiers. The aim is to achieve high efficiency at both peak and back-off power levels. In the scope of this thesis, a power amplifier design has been developed and manufactured using the Load Modulated Balanced Amplifier (LMBA) technique, operating in the frequency range of 1.7 GHz to 1.9 GHz with an output power of 47 dBm (50 W). The power amplifier design achieved a drain efficiency of 60.1 % - 63.3 % at maximum output power, and 40.5 % - 46.8 % drain efficiency at 6 dB output back-off power. The load modulated balanced amplifier, along with its subsystems, has been manufactured after finalizing the design. The produced LMBA system has been tested by using calibrated RF measurement instruments at RFTR Electronics Inc. facilities, where various measurements were conducted. As a result of these measurements, it was observed that the production results closely matched the simulation results. Furthermore, it was demonstrated that the efficiency of the system increased both at maximum output power and at 6 dB output back-off power when using the LMBA technique. Additionally, it is observed that power amplifiers designed by using the LMBA technique achieve better results compared to similar studies in the literature in terms of providing over 60 % drain efficiency at maximum output power throughout the entire operating band for power levels of at least 50 W, and over 40 % drain efficiency at 6 dB back-off power level.