In this white paper, a gallium arsenide (GaAs) pseudomorphic high-electron mobility transistor (pHEMT) power amplifier (PA) design approach is examined from a systems perspective. It highlights the design flow and its essential features for most PA design projects by illustrating a simple Class A GaAs pHEMT monolithic microwave IC (MMIC) PA design using Cadence® AWR® Microwave Office® circuit design software. The paper begins with the concepts of design closure and then describes parametric design as key concepts to understanding each step of the PA design process.