A New Highly Power-Efficient Inverse Class-D PA for NB-IoT Applications

The most power-consuming building blocks in Radio Frequency (RF) transceivers are power amplifiers (PAs). This paper presents a fully integrated inverse class-D power amplifier with high efficiency for narrowband Internet of Things (NB-IoT) applications. In this design, two auxiliary PMOS transistors to mitigate the power dissipation are inserted to the class-D ⁻¹ PA. In addition, power efficiency has been improved by selecting a proper value for RF choke. An on-chip balun is designed to combine the output power, while its primary winding resonates with a capacitor at the fundamental frequency simultaneously. Operating from a 1-V supply and in frequency band of 1850–1910 MHz, the proposed PA can achieve a peak PAE of 63.74% and delivers 17.5 dBm output power to a $50\ \mathbf{\Omega}$ load. By using 180 nm TSMC RF technology, the proposed PA occupies a total chip area of 1.19 mm ² , including pads.