A Fully-Integrated Efficient CMOS Inverse Class-D Power Amplifier for Digital Polar Transmitters

In this work, we have demonstrated a fully-integrated, high-efficiency CMOS inverse Class-D PA. Such efficient switching amplifiers can form the core of mixed-signal polar transmitters. A comprehensive analytical framework has been developed to determine optimum component values to maximize efficiency. Operating from a 1-V supply, the PA achieves a peak efficiency of 44% without any RF process options. This is comparable to that of state-of-the-art CMOS switching PAs despite using a much simpler output matching network.