6. A 28 GHz Inverse Class-D Power Amplifier

The chapter delves into the design and implementation of a 28 GHz Inverse Class-D Power Amplifier using Current Mode Class-D (CMCD) technology. It begins by explaining the principles of CMCD PAs and their advantages over conventional designs. The proposed amplifier utilizes a cascode configuration to overcome the limited breakdown voltage of devices, enabling higher output power. A novel pulse injection technique is introduced to improve efficiency by minimizing output parasitic capacitance. The chapter provides detailed simulation and measurement results, demonstrating a peak PAE of 46% and a peak DE of 71% at 19 dBm output power. The design is compared with state-of-the-art CMCD PAs, showcasing its superior performance at high frequencies. The chapter concludes by discussing the potential applications of the amplifier in outphasing transmitters or Doherty configurations to improve overall efficiency.