Direct Frequency Modulation of a High Temperature Silicon Carbide Oscillator

Abstract

This paper reports on direct frequency modulation of a RF Colpitts oscillator, realised from silicon carbide devices and proprietary components, capable of transmitting sensor data whilst operating at 300°C. Utilizing a reversed biased Schottky diode as a varactor in an LC oscillator, it is possible to modulate the frequency of an RF carrier by applying external voltage signals. These experiments have shown that a 10V bias will increase the frequency by as much as 10%, however signals as low as 10mV are easily detectable with standard silicon receivers.