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

This paper presents the design of a low-power (200mW) highly-efficient VHF Class-E amplifier that can be directly integrated with a small (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.38 \lambda$</tex>) 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 (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\lesssim 50 \Omega$</tex>) 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 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{6 0. 7 \%}$</tex> with an output power of 113.5mW for fixed supply voltage of 10V and power budget of less than 200 mW, whilst directly interfaced with a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$25-j 147 \Omega$</tex> small antenna load. This result demonstrates the potential of our proposed design approach to enable the miniaturization of small satellite communication systems.