Characterization of 720 and 940 MHz oscillators with chip antenna for wireless sensors from room temperature to 200 and 250 °C

Oscillators that operate at 720 and 940 MHz and characterized over a temperature range of 25°C to 200°C and 250°C, respectively, are presented. The oscillators are designed on alumina substrates with typical integrated circuit fabrication techniques. Cree SiC MESFETs, thin film metal-insulator-metal capacitors and spiral inductors, and Johanson miniature chip antennas make-up the circuits. The output power and phase noise are presented as a function of temperature and frequency.