CMOS Power Amplifier on Top of Embedded Transformer for Compact Module

A small-sized high-performance complementary metal-oxide-semiconductor (CMOS) power amplifier (PA) module is presented. To reduce insertion loss of the output matching network (OMN), an off-chip transformer is designed on a FR-4 printed circuit board (PCB). To minimize the area of the OMN, the transformer is embedded underneath the PA chip. Coupling between the PA and the transformer is minimized so that the performance is not affected. For the 7.5 dB peak-to-average power ratio, 16-QAM long-term evolution signal, the proposed CMOS PA module achieves a power-added efficiency of 38.5% and an adjacent channel leakage ratio level under ${-}31$ dBc at an average output power of 27.5 dBm. The proposed technique can be used in any wireless Tx applications requiring small form-factor and high performance.