In this work, we design a linear CMOS power amplifier with a spiral‐type output transformer for IEEE 802.11n WLAN applications. We conduct studies to identify the proper output transformer and power stage structures for linear CMOS power amplifiers. The power amplifier is composed of a single differential‐pair for the power stage to mitigate the stability problems that frequently arise in high gain linear power amplifiers. Additionally, we investigate the output matching network using a spiral‐type output transformer to minimize the output return loss. To verify the feasibility of the power amplifier, we designed a 2.4‐GHz power amplifier with a 180‐nm SOI CMOS process. The designed power amplifier is measured using an IEEE 802.11n WLAN signal. The power amplifier achieves 21.28 dBm output power while the measured EVM satisfies the standard for 802.11n applications. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:546–550, 2017