Development of a high-efficiency RF transmitter for satellites

• Main Author: Lim, Wei Liang
• Other Authors: Arokiaswami Alphones
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Engineering; Satellites; Transmitter
• Online Access: https://hdl.handle.net/10356/176224
• Institution: Nanyang Technological University

This final year report presents the development of a high-efficiency RF transmitter for satellites. Conventional RF power amplifiers have low power efficiency, resulting in high energy consumption and heat dissipation. A technique known as Envelope Tracking can enable the RF power amplifier to achieve better efficiency. Hence, this project will study the use of Envelope Tracking techniques to improve the efficiency of an RF power amplifier on an X- band (8.025 to 8.4 GHz) satellite. This report provides a literature review of the classes of power amplifiers, the performance parameters of the power amplifiers, the working principles of Envelope Tracking, the types of Envelope Tracking supply modulators, and GaN transistors. This report will also describe the use of software like LTSpice for the simulation of the supply modulator and the familiarisation process of using PathWave Advanced Design System (ADS) for implementing Envelope Tracking on a GaN transistor and simulating using only Harmonic Balance. This report will share the results from the simulations conducted using ADS. The results show that Envelope Tracking can improve the efficiency of the GaN transistor by up to 12%. This indicates that Envelope Tracking can potentially improve the efficiency of a built-up RF power amplifier using a GaN transistor. The report concludes with the possibilities for future works, including testing the GaN transistor at the operating frequency, building an RF power amplifier using different GaN transistors, and carrying out the simulations with the Circuit Envelope simulation tool for a better representation of the system.