A built-in linearizer was applied to improve the linearity in a 5.2-GHz power amplifier microwave monolithic integrated circuit(MMIC),which was undertaken with 0.15-μm AlGaAs/InGaAs D-mode PHEMT technology. The power amplifier(PA) was studied taking into account the linearizer circuit and the coplanar waveguide(CPW) structures.Based on these technologies,the power amplifier,which has a chip size of 1.44×1.10 mm~2,obtained an output power of 13.3 dBm and a power gain of 14 dB in the saturation region.An input third-order intercept point (IIP_3) of-3 dBm,an output third-order intercept point(OIP_3) of 21.1 dBm and a power added efficiency(PAE) of 22% were attained,respectively.Finally,the overall power characterization exhibited high gain and high linearity,which illustrates that the power amplifier has a compact circuit size and exhibits favorable RF characteristics.This power circuit demonstrated high RF characterization and could be used for microwave power circuit applications at 5.2 GHz. A built-in linearizer was applied to improve the linearity in a 5.2-GHz power amplifier microwave monolithic integrated circuit (MMIC), which was undertaken with 0.15-μm AlGaAs / InGaAs D-mode PHEMT technology. The power amplifier (PA) was studied taking into account the linearizer circuit and the coplanar waveguide (CPW) structures. Based on these technologies, the power amplifier, which has a chip size of 1.44 × 1.10 mm ~ 2, obtains an output power of 13.3 dBm and a power gain of 14 dB in the saturation region. An input third-order intercept point (IIP_3) of-3 dBm, an output third-order intercept point (OIP_3) of 21.1 dBm and a power added efficiency (PAE) of 22% were attained, respectively. Finally, the overall power characterization exhibited high gain and high linearity, which illustrates that the power amplifier has a compact circuit size and exhibits favorable RF characteristics. This power circuit demonstrated high RF characterization and could be used for microwave power circuit applications at 5 .2 GHz.