Design of a Power Amplification System for S-Band Satellite Applications

Abstract

The satellite industry is in more demand than ever for more efficient satellites as they are getting smaller, and with it, the on-board power resources are also getting more limited. The high-power amplification section of the satellite consumes most of the power supplied to the system and is usually the least efficient subsystem of the satellite. Therefore, more efficient power amplification systems are vital for the upcoming small-satellites applications. To address this issue, a high-efficiency power amplification system with acceptable linearity performance is proposed. This system is designed to work in the S-band, specifically around the 3.5 GHz center frequency, with a targeted high efficiency in the range of 60% to 70% at a 6 dB output power backoff. The system is composed of two high efficiency amplifiers operating in the Doherty configuration which results in the high back-off efficiency. Simulations of the system were carried out using Advanced Design System (ADS) software with a large signal model of CGH40010F from Cree-Wolfspeed, which resulted in 62% to 75% of Power Added Efficiency (PAE) at peak output power of 43 dBm. The amplifier’s layout was then generated and tuned. The prototyped amplifier achieved an efficiency of 35% at 6 dB back-off and a maximum efficiency of 52% at peak power. It also meets out-of-band spectrum emission requirements for a satellite transmitter. Finally, the amplifier was linearized using digital predistortion (DPD) to ensure meeting the requirements of high order modulation schemes.