Design and implementation of a high-precision temperature controller

Abstract

This thesis presents the design, implementation and experimental validation of a highprecision, high-power temperature controller intended to support low-noise semiconductor device characterisation measurements at the Institute of Microelectronics, TU Wien. Existing commercial systems provide seriously limited voltage range, insufficient electric noise performance, or lack an open interface that would allow the use of efficient control algorithms other than their built-in PID regulators. The objective of this work was to develop a versatile temperature controller capable of supporting multiple systems, including a resistive oven and a thermoelectric module, while achieving low electrical noise and high temperature accuracy. The system combines a custom high-voltage linear amplifier, low-noise measurement circuitry and a real-time microcontroller firmware with modular experiment modes, USB communication, touchscreen operation and comprehensive safety supervision features such as over current and temperature detection, short-circuit safe operation and more.The hardware was validated electrically using oscilloscope measurements and thermally by implementing PID-based controllers for both the oven and the thermoelectric setups. The final system achieves an output voltage range from −18V to 70V with a voltage noise below 3.5mVrms and supports currents up to 7A. The temperature control loop operates at 5 Hz and achieves a steady state accuracy of approximately ±35mK for the oven setup and ±25mK for the thermoelectric setup. The temperature sensor provides an accuracy of up to ±10mK. All implemented safety mechanisms, including over current detection, fuse protection and firmware level supervision, were verified experimentally.The results demonstrate that the prototype meets the requirements of most experimental setups at the Institute and provides a flexible platform for future developments. Due to its modular hardware architecture and extensible firmware design, the system also enables the implementation and evaluation of advanced control strategies, offering a promising foundation for further research.