This letter presents the design approach for a compact, single-stage, wideband MMIC power amplifier. A method is proposed to compensate for the output capacitance of the active device over a frequency range as wide as possible, with minimum impact on the achievable output power, which leads to a two-element compensating network. A three-section transformer is then adopted for a real-to-real transformation. The CW characterization shows the output power higher than 32 dBm and the drain efficiency between 35% and 45%, over a fractional bandwidth of 148%, from 3 to 20 GHz.