A digitally controlled PA with tunable matching network

A class AB power amplifier (PA) with output power digital controllability for WSNs is implemented in 65nm CMOS technology. The programmable output power is realized by altering the number of working cells and adjusting the load through a tunable matching network, which can increase the back-off efficiency significantly. Dummy FETs are used for neutralization to increase reverse isolation. The measurement results show a peak output power of 3dBm and a PAE of 40% with a 1.2V supply. Drain efficiency at back off (above 3dB) increases by more than 10%, comparing to traditional digital controlled PA.