A Ku-band power amplifier monolithic microwave integrated circuit (MMIC) with an output power density of 726 mW/mm2 is demonstrated using 0.25 ??m SiGe BiCMOS technology. No inductor matching scheme is applied to minimize the MMIC size, but an active biasing topology is used to enhance the power-added efficiency (PAE) and linearity of the MMIC. The fabricated one-stage cascode power amplifier MMIC, including input/output matching and biasing circuits, has a compact size of 0.384 mm2 (0.6 mm ?? 0.64 mm), and exhibits a saturated output power (Psat) of 24.45 dBm and a PAE of 29.1 % at 14 GHz.