A new variable RF power ratio splitter based on the variation of output impedances in the presence of an RF power transistor

RF power splitters are critical components in the design of complex RF power amplifiers. On the other hand, amplitude-based power splitters can provide notable advantages in some configurations, as, for example, in Doherty amplifiers. Among the power splitter structures, hybrid branch line couplers (HBLC) are widely utilized as power splitters. However, conventional HBLCs have limitations in achieving varying power ratios between the input and output without altering the characteristic impedances within the structure. Moreover, modifying the output terminal impedances does not have a useful effect on the power ratio delivered between the two output ports at the center frequency. In this paper, we analyze the standard HBLC structure, focusing on the voltage and power relationship, to identify the factors influencing this behavior. By modifying a parameter in the physical structure, we propose a novel simple configuration that adjusts the power ratio between input and output while varying the delivered power ratio between the two output ports, based on changes in output impedances. Then, we demonstrate the utilization of nonlinearity in a GaN HEMT transistor at its input’s nonlinear region. We showcased an amplitude-based nonlinear power splitter with a customizable power ratio profile by modifying the input networks.