Oscilador pierce com sensor a ondas de love na malha de realimentação

Abstract

Sensors based on surface acoustic waves can be used in measurement systems to detect biological and chemical agents such as: virus, bacteria and various toxins in liquid medium. For this, it is necessary to develop a specific electronic circuit to be used in conjunction with the sensor and one of the possible architectures uses an oscillator circuit. In this way, this work deals with the design and simulation of a sinusoidal oscillator using a SAW biosensor in the feedback loop. The goal is to model a sensor based on Love waves and use the model in a feedback loop with an amplifier in order to design an oscillator whose frequency is dependent on disturbances on the sensor surface. The initial frequency of oscillation must be that in which the sensor has minimal losses. This frequency corresponds to the resonance frequency, so it is necessary to identify it. Using a vector network analyzer, the frequency of 117.6 MHz was identified. After identification, parameters corresponding to an equivalent model for the device were extracted. This model was used in order to simulate a Pierce oscillator circuit.