Highly-Efficient and Low-Power Class-E Amplifier for Miniaturization using a Small Antenna

This paper presents the design of a low-power (200\,mW) highly efficient VHF Class-E amplifier that can be directly integrated with a small ($0.38\lambda$) dipole CubeSat satellite antenna. This design is enabled by our novel procedure to shape the transistor drain voltage and current waveforms using only the conventional Class-E load circuit components. Our method attains a Class-E amplifier with a fundamental optimum load impedance equal to the low resistance ($\lesssim 50\,\Omega$) and capacitance of a small antenna and simultaneously maximizes the drain efficiency for fixed output power and supply voltage. The prototype achieves a power-added efficiency (PAE) of 60.7\% with an output power of 113.5\,mW for fixed supply voltage of 10\,V and power budget of less than 200\,mW, whilst directly interfaced with a $25-j147\,\Omega$ small antenna load. This result demonstrates the potential of our proposed design approach to enable the miniaturization of small satellite communication systems.