Design of a Radiofrequency Power Amplifier test setup using a Hybrid-Based RF Amplifier

The principle focus of this work is how to design, using components generally available on the market, a novel linear RF power amplifier that includes the ability to measure the return loss of the device connected to its output. This extended functionality is achieved by combining two linear RF power amplifiers using 90-degree hybrids. By repurposing the Isolated port (hereinafter referred to as the “error port”, the return loss measurement capability is achieved. This thesis shows how to design such a power amplifier. A DC load line is used to find the starting values for a load-pull analysis. The detailed load-pull analysis is then performed to determine the optimum load and source impedance for the amplifier based on its desired output power and the intended DC supply voltage. In addition, the work shows how to design the input and output matching networks of the linear power amplifier, as well as the DC-feed networks that supply DC power and set the bias point. The output power capability and the ability of the hybrid-coupled linear power amplifier to measure the return loss of the attached load are also discussed in detail. The RF power amplifier was built using PCB technology, the design was verified, and the amplifier performance was measured and compared to expectations derived from modelling.