A CMOS POWER AMPLIFIER USING A BALUN EMBEDDED DRIVER STAGE FOR IEEE 802.11N WLAN APPLICATIONS

In this work, we propose a balun embedded driver stage to enhance the bandwidth and minimize the chip size of a differential CMOS power amplifier. By removing the passive input transformer, the bandwidth and chip size are improved. The proposed driver stage acts as an input balun as well as the driver stage for the power stage. The proposed driver is composed of a cascade connected PMOS, an inductor, and NMOS to generate the differential output signal. For the function of the input balun, the gate of the PMOS is connected to the drain of the NMOS. To verify the feasibility of the proposed balun embedded driver stage, we design a differential CMOS power amplifier for 5-GHz IEEE 802.11n WLAN applications. The designed power amplifier is fabricated using the 180-nm SOI RF CMOS process. The measured 3-dB bandwidth is approximately 2.5 GHz. The chip size of the fully integrated power amplifier, including input and output matching networks and test pads, is 0.885 mm2. The measured maximum output power is 20.18 dBm with a PAE of 10.16%.