High Temperature Capacitive Pressure Sensor Employing a SiC Based Ring Oscillator

Smart sensor systems that can operate at high temperatures are required for a range of aerospace applications such as propulsion [1]. For future aerospace propulsion systems to meet the requirements of decreased maintenance, improved performance, and increased safety, the inclusion of intelligence into the propulsion system design and operation is necessary. This implies the development of sensor systems able to operate under the harsh environments present in an engine. Likewise, applications such as Venus exploration missions require systems that can operate in the harsh environments present on the Venus planetary surface. More sensor systems added to the aircraft increases the number of wires and the associated weight, complexity, and potential for failure. Thus, there is a need not only for high temperature sensors and electronics, but also for high temperature wireless technology. This implies the integration of sensors, electronics, wireless circuits, and power into a single system. In this paper, we demonstrate a significant step towards this goal, i.e., for the first time the integration of a pressure sensor with a SiC JFET logic-gate ring oscillator that operates at 500 °C; the sensor output signal is extracted from the small-signal ring oscillation frequency detected at the powersupply end of the DC power wires.