In this paper, novel linearization technique is proposed to realize a 5-GHz band linear CMOS power amplifier IC for WLAN application. The novel linearizer which consists of a diode-connected PMOS bias circuit and a PMOS varactor connected in parallel with an NMOS amplifier is effectively to suppress the gain compression and phase distortion of the power amplifier. A CMOS power amplifier IC is designed, fabricated and fully tested using TSMC 0.13-μπι CMOS technology. With these proposed techniques, the measurement results show a third-order IMD improvement of 9 dB over wide output power range and the maximum improvement of 18 dB. The power amplifier IC exhibits an output PldB of 19.5 dBm and a power gain of 9.5 dB at an operation voltage of 3.3 V.