Performance Analysis of a Differential Pair Oscillator with SAW Sensor in Feedback Loop

In this paper is presented the performance analysis of a differential pair sinusoidal oscillator with a surface acoustic wave sensor in the feedback loop. The oscillator components were selected for an oscillation frequency of 117.6 MHz and the SAW sensor model used was based on a piezoelectric crystal. The oscillator performance was verified through computer simulations by analysing the oscillation frequency and the amplitude of the the output voltage. The first analysis showed an amplitude greater than zero and an oscillation frequency close to the resonance frequency of the sensor model. Subsequently, the oscillator performance was analyzed by varying the value of one component at a time using Monte Carlo method. Based on this analysis, it was possible to determine a range of values for each component in which the output maintains oscillation. Finally, the oscillator's performance was analyzed with simultaneous variation in the values of its components. For this simulation, the range of values found in the previous analysis was used, and the variation was carried out using the Monte Carlo method. In this case, the circuit maintains oscillation in 76.8% of the iterations. These results confirm that the oscillator performance is adequate, maintaining oscillation even with variations in the values of its components.