High-temperature electronic components and circuit designs

Downhole logging instruments for geothermal application must have electronic circuits capable of operating from room temperature to 250/sup 0/C. Previous research was centered on low voltage/low current hybrid microcircuits. However, a nondestructive evaluation (NDE) instrument for geothermal wells requires a circuit that can be operated at high voltage and high current in order to provide high-power output. In designing such a circuit, Sandia Laboratories is developing a high-power, high-speed, cold-cathode switching tube to be used as a substitute for SCRs or thyratrons. The possibility of using low-leakage JFETs beyond their rated temperature in a circuit design will be discussed. Commercial high-temperature components will be reviewed