Integrated transformer baluns for RF low noise and power amplifiers

On-chip transformer baluns integrated with an RF front-end architecture for medium power WLAN is presented. Method of measuring and characterizing a 3-port balun with a 2-port network analyzer is discussed. Implemented in 0.18mum CMOS, the receive path including a switch, an input transformer and a differential LNA, achieves S
₂₁
of 17dB, NF of 4.1dB, and IIP3 of 0dBm at 2.45GHz; the transmit path of a differential PA with an output transformer, achieves P
_sat
of 21dBm, P
_1dB
of 17dBm, and max PAE of 21%