3.6 GHz Integrated Inverse Class-E Amplifier with Polar Modulation Capability

This work presents an inverse class-E switching power amplifier with the capability of phase and amplitude modulation. Advantages of this amplifier topology, like a higher integrability caused by smaller inductors, compared to an conventional shunt-C/serial-filtered class-E amplifier will be made clear. This paper outlines the conceptual approach for an analog RF front-end polar transmitter without a mixer. The circuit is designed for low-power mobile applications at 3.6 GHz and fabricated in a 45 nm CMOS process. In laboratory measurements, the amplifiers system efficiency and drain efficiency (DE) at a maximum output power of 6.8 dBm reaches 36.9 % and 49.0 %, respectively. The active chip core size is merely 0.21 mm2.