A Voltage-Mode Class-S Power Amplifier for the 450MHz Band

Published in:
European Microwave Conf. (EuMC 2010), Paris, France, Sep. 28-30, pp. 640-643 (2010).
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Abstract:
This paper reports on a novel voltage-mode class-S power amplifier for the 450 MHz band, based on GaN-HEMT MMICs. It achieves a peak output power of 3.4 W for a single tone at 400 MHz, encoded in standard band-pass delta-sigma modulation with 1.6 Gbps sampling frequency. The corresponding efficiency is 38%, peaking at 52% for 0.5 W output power. In order to demonstrate the influence of coding efficiency, additional measurements using a periodic squarewave signal were performed (class-D operation), which yield a maximum output power of 6.5 W with 64% efficiency. To the authors knowledge, these are the best results in this frequency range achieved so far with the voltage-mode class-S configuration.

Keywords:
power amplifier, class-S, voltage-mode, GaN, HEMT, switch-mode, band-pass delta-sigma modulation.

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