A 31.5 %, 26 dBm LTE CMOS power amplifier with harmonic control

A 1.85GHz linear differential CMOS power amplifier with a printed board circuit based transformer is developed. A 2^nd harmonic short circuit at an input is proposed to achieve high linearity. Simulation result shows that the third-order intermodulation distortion level decreases throughout the low and mid power regions, indicating that the 2^nd harmonic short compresses the C_gs nonlinearity effectively. The proposed CMOS PA is fabricated using 0.18 μm RF CMOS technology. This PA delivers a power-added efficiency of 31.5 % and the adjacent channel leakage ratio of -32 dBc at an output power of 26 dBm for the 10 MHz bandwidth long-term evolution signal.