Ruggedized RF Transmitter Design for High-Temperature Aerospace Environments

Abstract

The growing need to have reliable wireless communication systems in the aerospace platforms also requires the need to have RF transmitter architecture that can maintain its capability to operate under the extreme environment especially the high temperature and radiation environment. This paper gives full design, modeling and validation of a ruggedized RF transmitter that can be used with aerospace environment where ambient temperatures can reach a high temperature of 250C. The main building block of the proposed architecture is a power amplifier based on GaN that is predicted to have better heat tolerance and higher power ratings than silicon- or gallium arsenide-based predecessors. The system is thermally stable with temperature-compensated biasing circuit and effective thermal system with ceramic boards and heat-spreading case. The signal travel path with components radiation-hardened is used across the signal chain to provide greater survivability in high altitude and deep space conditions where total ionizing dose and latch-up conditions are major concerns. To thoroughly validate the design, a combination of ADS and CST co-simulation is used to characterize the RF performance, thermal modeling is done in COMSOL, and testing is done under both accelerated thermal cycling and radiation stress conditions. At 5.8 GHz the transmitter delivers a maximum power output of 28 dBm and high power beyond 42% power-added efficiency (PAE) and all within a wide temperature range with less than 1.2 dB variation in gain. Moreover, the system portrays stable impedance matching (S11 < -10 dB), low bit error rates when subjected to QPSK modulation, and negligible degradation of performance even under radiation dose of 100 krad(Si). This project not only proves that high temperature RF communications is not only possible in aerospace but also defines the design process of its future ruggedized communicational modules targeting high-altitude drones, planetary entry systems, and spacecraft payloads. The combination of rugged thermally and radiatively robust components in a small scale, mass producible transmitter platform is a first in the RF/harsh environment electronic arena of aerospace.