Demonstration of a silicon gated field emitter array based low frequency Colpitts oscillator at 400 °C

Silicon gated field emitter arrays have been used as a vacuum transistor to demonstrate a 152 kHz Colpitts oscillator. The transfer and output characteristics of the 1000 x 1000 silicon arrays were measured using a collector placed & AP; 1 mm away with a gate voltage up to 40 V and a collector voltage up to 200 V. The data were used to establish an LTspice transistor model based on a field emission tip model and a collector current model that fit the characteristics. Then, the LTspice model was used to design a low frequency Colpitts oscillator. Furthermore, experiments were carried out to successfully demonstrate the oscillation. Oscillation frequency was 152 kHz with a peak to peak voltage of 25 V for a tip to ground series resistance value of 10 k Omega at 50 V on the gate and 210 V on the collector. Further, the oscillator was also tested at 50, 100, 200, 300, and 400 degrees C. It was observed that frequency shifts for each temperature which is due to the change in the overall capacitance of the test setup. This type of device could be used as a temperature sensor in harsh environments.